// Copyright (C) 2023 Vitaliy Lobachevskiy
// Copyright (C) 2014 Patryk Nadrowski
// Copyright (C) 2009-2010 Amundis
// This file is part of the "Irrlicht Engine".
// For conditions of distribution and use, see copyright notice in Irrlicht.h

#include "Driver.h"
#include <cassert>
#include "CNullDriver.h"
#include "IContextManager.h"

#include "COpenGLCoreTexture.h"
#include "COpenGLCoreRenderTarget.h"
#include "COpenGLCoreCacheHandler.h"

#include "MaterialRenderer.h"
#include "FixedPipelineRenderer.h"
#include "Renderer2D.h"

#include "EVertexAttributes.h"
#include "CImage.h"
#include "os.h"

#ifdef _IRR_COMPILE_WITH_ANDROID_DEVICE_
#include "android_native_app_glue.h"
#endif

#include "mt_opengl.h"

namespace irr
{
namespace video
{
	struct VertexAttribute {
		enum class Mode {
			Regular,
			Normalized,
			Integral,
		};
		int Index;
		int ComponentCount;
		GLenum ComponentType;
		Mode mode;
		int Offset;
	};

	struct VertexType {
		int VertexSize;
		int AttributeCount;
		VertexAttribute Attributes[];

		VertexType(const VertexType &) = delete;
		VertexType &operator= (const VertexType &) = delete;
	};

	static const VertexAttribute *begin(const VertexType &type)
	{
		return type.Attributes;
	}

	static const VertexAttribute *end(const VertexType &type)
	{
		return type.Attributes + type.AttributeCount;
	}

	static constexpr VertexType vtStandard = {
		sizeof(S3DVertex), 4, {
			{EVA_POSITION, 3, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertex, Pos)},
			{EVA_NORMAL, 3, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertex, Normal)},
			{EVA_COLOR, 4, GL_UNSIGNED_BYTE, VertexAttribute::Mode::Normalized, offsetof(S3DVertex, Color)},
			{EVA_TCOORD0, 2, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertex, TCoords)},
		},
	};

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Winvalid-offsetof"

	static constexpr VertexType vt2TCoords = {
		sizeof(S3DVertex2TCoords), 5, {
			{EVA_POSITION, 3, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertex2TCoords, Pos)},
			{EVA_NORMAL, 3, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertex2TCoords, Normal)},
			{EVA_COLOR, 4, GL_UNSIGNED_BYTE, VertexAttribute::Mode::Normalized, offsetof(S3DVertex2TCoords, Color)},
			{EVA_TCOORD0, 2, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertex2TCoords, TCoords)},
			{EVA_TCOORD1, 2, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertex2TCoords, TCoords2)},
		},
	};

	static constexpr VertexType vtTangents = {
		sizeof(S3DVertexTangents), 6, {
			{EVA_POSITION, 3, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertexTangents, Pos)},
			{EVA_NORMAL, 3, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertexTangents, Normal)},
			{EVA_COLOR, 4, GL_UNSIGNED_BYTE, VertexAttribute::Mode::Normalized, offsetof(S3DVertexTangents, Color)},
			{EVA_TCOORD0, 2, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertexTangents, TCoords)},
			{EVA_TANGENT, 3, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertexTangents, Tangent)},
			{EVA_BINORMAL, 3, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertexTangents, Binormal)},
		},
	};

#pragma GCC diagnostic pop

	static const VertexType &getVertexTypeDescription(E_VERTEX_TYPE type)
	{
		switch (type) {
			case EVT_STANDARD: return vtStandard;
			case EVT_2TCOORDS: return vt2TCoords;
			case EVT_TANGENTS: return vtTangents;
			default: assert(false);
		}
	}

	static constexpr VertexType vt2DImage = {
		sizeof(S3DVertex), 3, {
			{EVA_POSITION, 3, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertex, Pos)},
			{EVA_COLOR, 4, GL_UNSIGNED_BYTE, VertexAttribute::Mode::Normalized, offsetof(S3DVertex, Color)},
			{EVA_TCOORD0, 2, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertex, TCoords)},
		},
	};

	static constexpr VertexType vtPrimitive = {
		sizeof(S3DVertex), 2, {
			{EVA_POSITION, 3, GL_FLOAT, VertexAttribute::Mode::Regular, offsetof(S3DVertex, Pos)},
			{EVA_COLOR, 4, GL_UNSIGNED_BYTE, VertexAttribute::Mode::Normalized, offsetof(S3DVertex, Color)},
		},
	};


void APIENTRY COpenGL3DriverBase::debugCb(GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length, const GLchar *message, const void *userParam)
{
	((COpenGL3DriverBase *)userParam)->debugCb(source, type, id, severity, length, message);
}

void COpenGL3DriverBase::debugCb(GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length, const GLchar *message)
{
	printf("%04x %04x %x %x %.*s\n", source, type, id, severity, length, message);
}

COpenGL3DriverBase::COpenGL3DriverBase(const SIrrlichtCreationParameters& params, io::IFileSystem* io, IContextManager* contextManager) :
	CNullDriver(io, params.WindowSize), COpenGL3ExtensionHandler(), CacheHandler(0),
	Params(params), ResetRenderStates(true), LockRenderStateMode(false), AntiAlias(params.AntiAlias),
	MaterialRenderer2DActive(0), MaterialRenderer2DTexture(0), MaterialRenderer2DNoTexture(0),
	CurrentRenderMode(ERM_NONE), Transformation3DChanged(true),
	OGLES2ShaderPath(params.OGLES2ShaderPath),
	ColorFormat(ECF_R8G8B8), ContextManager(contextManager)
{
#ifdef _DEBUG
	setDebugName("Driver");
#endif

	if (!ContextManager)
		return;

	ContextManager->grab();
	ContextManager->generateSurface();
	ContextManager->generateContext();
	ExposedData = ContextManager->getContext();
	ContextManager->activateContext(ExposedData, false);
	GL.LoadAllProcedures(ContextManager);
	GL.DebugMessageCallback(debugCb, this);
	initQuadsIndices();
}

COpenGL3DriverBase::~COpenGL3DriverBase()
{
	deleteMaterialRenders();

	CacheHandler->getTextureCache().clear();

	removeAllRenderTargets();
	deleteAllTextures();
	removeAllOcclusionQueries();
	removeAllHardwareBuffers();

	delete MaterialRenderer2DTexture;
	delete MaterialRenderer2DNoTexture;
	delete CacheHandler;

	if (ContextManager)
	{
		ContextManager->destroyContext();
		ContextManager->destroySurface();
		ContextManager->terminate();
		ContextManager->drop();
	}
}

	void COpenGL3DriverBase::initQuadsIndices(int max_vertex_count)
	{
		int max_quad_count = max_vertex_count / 4;
		std::vector<GLushort> QuadsIndices;
		QuadsIndices.reserve(6 * max_quad_count);
		for (int k = 0; k < max_quad_count; k++) {
			QuadsIndices.push_back(4 * k + 0);
			QuadsIndices.push_back(4 * k + 1);
			QuadsIndices.push_back(4 * k + 2);
			QuadsIndices.push_back(4 * k + 0);
			QuadsIndices.push_back(4 * k + 2);
			QuadsIndices.push_back(4 * k + 3);
		}
		glGenBuffers(1, &QuadIndexBuffer);
		glBindBuffer(GL_ARRAY_BUFFER, QuadIndexBuffer);
		glBufferData(GL_ARRAY_BUFFER, sizeof(QuadsIndices[0]) * QuadsIndices.size(), QuadsIndices.data(), GL_STATIC_DRAW);
		glBindBuffer(GL_ARRAY_BUFFER, 0);
		QuadIndexCount = QuadsIndices.size();
	}

	void COpenGL3DriverBase::initVersion() {
		Name = glGetString(GL_VERSION);
		printVersion();

		// print renderer information
		VendorName = glGetString(GL_VENDOR);
		os::Printer::log(VendorName.c_str(), ELL_INFORMATION);

		Version = getVersionFromOpenGL();
	}

	bool COpenGL3DriverBase::isVersionAtLeast(int major, int minor) const noexcept {
		if (Version.Major < major)
			return false;
		if (Version.Major > major)
			return true;
		return Version.Minor >= minor;
	}

	bool COpenGL3DriverBase::genericDriverInit(const core::dimension2d<u32>& screenSize, bool stencilBuffer)
	{
		initVersion();
		initFeatures();

		// reset cache handler
		delete CacheHandler;
		CacheHandler = new COpenGL3CacheHandler(this);

		StencilBuffer = stencilBuffer;

		DriverAttributes->setAttribute("MaxTextures", (s32)Feature.MaxTextureUnits);
		DriverAttributes->setAttribute("MaxSupportedTextures", (s32)Feature.MaxTextureUnits);
//		DriverAttributes->setAttribute("MaxLights", MaxLights);
		DriverAttributes->setAttribute("MaxAnisotropy", MaxAnisotropy);
//		DriverAttributes->setAttribute("MaxUserClipPlanes", MaxUserClipPlanes);
//		DriverAttributes->setAttribute("MaxAuxBuffers", MaxAuxBuffers);
//		DriverAttributes->setAttribute("MaxMultipleRenderTargets", MaxMultipleRenderTargets);
		DriverAttributes->setAttribute("MaxIndices", (s32)MaxIndices);
		DriverAttributes->setAttribute("MaxTextureSize", (s32)MaxTextureSize);
		DriverAttributes->setAttribute("MaxTextureLODBias", MaxTextureLODBias);
		DriverAttributes->setAttribute("Version", 100 * Version.Major + Version.Minor);
		DriverAttributes->setAttribute("AntiAlias", AntiAlias);

		glPixelStorei(GL_PACK_ALIGNMENT, 1);

		UserClipPlane.reallocate(0);

		for (s32 i = 0; i < ETS_COUNT; ++i)
			setTransform(static_cast<E_TRANSFORMATION_STATE>(i), core::IdentityMatrix);

		setAmbientLight(SColorf(0.0f, 0.0f, 0.0f, 0.0f));
		glClearDepthf(1.0f);

		glHint(GL_GENERATE_MIPMAP_HINT, GL_NICEST);
		glFrontFace(GL_CW);

		// create material renderers
		createMaterialRenderers();

		// set the renderstates
		setRenderStates3DMode();

		// set fog mode
		setFog(FogColor, FogType, FogStart, FogEnd, FogDensity, PixelFog, RangeFog);

		// create matrix for flipping textures
		TextureFlipMatrix.buildTextureTransform(0.0f, core::vector2df(0, 0), core::vector2df(0, 1.0f), core::vector2df(1.0f, -1.0f));

		// We need to reset once more at the beginning of the first rendering.
		// This fixes problems with intermediate changes to the material during texture load.
		ResetRenderStates = true;

		testGLError(__LINE__);

		return true;
	}

	void COpenGL3DriverBase::loadShaderData(const io::path& vertexShaderName, const io::path& fragmentShaderName, c8** vertexShaderData, c8** fragmentShaderData)
	{
		io::path vsPath(OGLES2ShaderPath);
		vsPath += vertexShaderName;

		io::path fsPath(OGLES2ShaderPath);
		fsPath += fragmentShaderName;

		*vertexShaderData = 0;
		*fragmentShaderData = 0;

		io::IReadFile* vsFile = FileSystem->createAndOpenFile(vsPath);
		if ( !vsFile )
		{
			core::stringw warning(L"Warning: Missing shader files needed to simulate fixed function materials:\n");
			warning += core::stringw(vsPath) + L"\n";
			warning += L"Shaderpath can be changed in SIrrCreationParamters::OGLES2ShaderPath";
			os::Printer::log(warning.c_str(), ELL_WARNING);
			return;
		}

		io::IReadFile* fsFile = FileSystem->createAndOpenFile(fsPath);
		if ( !fsFile )
		{
			core::stringw warning(L"Warning: Missing shader files needed to simulate fixed function materials:\n");
			warning += core::stringw(fsPath) + L"\n";
			warning += L"Shaderpath can be changed in SIrrCreationParamters::OGLES2ShaderPath";
			os::Printer::log(warning.c_str(), ELL_WARNING);
			return;
		}

		long size = vsFile->getSize();
		if (size)
		{
			*vertexShaderData = new c8[size+1];
			vsFile->read(*vertexShaderData, size);
			(*vertexShaderData)[size] = 0;
		}

		size = fsFile->getSize();
		if (size)
		{
			// if both handles are the same we must reset the file
			if (fsFile == vsFile)
				fsFile->seek(0);

			*fragmentShaderData = new c8[size+1];
			fsFile->read(*fragmentShaderData, size);
			(*fragmentShaderData)[size] = 0;
		}

		vsFile->drop();
		fsFile->drop();
	}

	void COpenGL3DriverBase::addDummyMaterial(E_MATERIAL_TYPE type) {
		auto index = addMaterialRenderer(getMaterialRenderer(EMT_SOLID), "DUMMY");
		assert(index == type);
	}

	void COpenGL3DriverBase::createMaterialRenderers()
	{
		// Create callbacks.

		COpenGL3MaterialSolidCB* SolidCB = new COpenGL3MaterialSolidCB();
		COpenGL3MaterialSolidCB* TransparentAlphaChannelCB = new COpenGL3MaterialSolidCB();
		COpenGL3MaterialSolidCB* TransparentAlphaChannelRefCB = new COpenGL3MaterialSolidCB();
		COpenGL3MaterialSolidCB* TransparentVertexAlphaCB = new COpenGL3MaterialSolidCB();
		COpenGL3MaterialOneTextureBlendCB* OneTextureBlendCB = new COpenGL3MaterialOneTextureBlendCB();

		// Create built-in materials.
		// The addition order must be the same as in the E_MATERIAL_TYPE enumeration. Thus the
		// addDummyMaterial calls for materials no longer supported.

		const core::stringc VertexShader = OGLES2ShaderPath + "Solid.vsh";

		// EMT_SOLID
		core::stringc FragmentShader = OGLES2ShaderPath + "Solid.fsh";
		addHighLevelShaderMaterialFromFiles(VertexShader, "main", EVST_VS_2_0, FragmentShader, "main", EPST_PS_2_0, "", "main",
			EGST_GS_4_0, scene::EPT_TRIANGLES, scene::EPT_TRIANGLE_STRIP, 0, SolidCB, EMT_SOLID, 0);

		addDummyMaterial(EMT_SOLID_2_LAYER);
		addDummyMaterial(EMT_LIGHTMAP);
		addDummyMaterial(EMT_LIGHTMAP_ADD);
		addDummyMaterial(EMT_LIGHTMAP_M2);
		addDummyMaterial(EMT_LIGHTMAP_M4);
		addDummyMaterial(EMT_LIGHTMAP_LIGHTING);
		addDummyMaterial(EMT_LIGHTMAP_LIGHTING_M2);
		addDummyMaterial(EMT_LIGHTMAP_LIGHTING_M4);
		addDummyMaterial(EMT_DETAIL_MAP);
		addDummyMaterial(EMT_SPHERE_MAP);
		addDummyMaterial(EMT_REFLECTION_2_LAYER);
		addDummyMaterial(EMT_TRANSPARENT_ADD_COLOR);

		// EMT_TRANSPARENT_ALPHA_CHANNEL
		FragmentShader = OGLES2ShaderPath + "TransparentAlphaChannel.fsh";
		addHighLevelShaderMaterialFromFiles(VertexShader, "main", EVST_VS_2_0, FragmentShader, "main", EPST_PS_2_0, "", "main",
			EGST_GS_4_0, scene::EPT_TRIANGLES, scene::EPT_TRIANGLE_STRIP, 0, TransparentAlphaChannelCB, EMT_TRANSPARENT_ALPHA_CHANNEL, 0);

		// EMT_TRANSPARENT_ALPHA_CHANNEL_REF
		FragmentShader = OGLES2ShaderPath + "TransparentAlphaChannelRef.fsh";
		addHighLevelShaderMaterialFromFiles(VertexShader, "main", EVST_VS_2_0, FragmentShader, "main", EPST_PS_2_0, "", "main",
			EGST_GS_4_0, scene::EPT_TRIANGLES, scene::EPT_TRIANGLE_STRIP, 0, TransparentAlphaChannelRefCB, EMT_SOLID, 0);

		// EMT_TRANSPARENT_VERTEX_ALPHA
		FragmentShader = OGLES2ShaderPath + "TransparentVertexAlpha.fsh";
		addHighLevelShaderMaterialFromFiles(VertexShader, "main", EVST_VS_2_0, FragmentShader, "main", EPST_PS_2_0, "", "main",
			EGST_GS_4_0, scene::EPT_TRIANGLES, scene::EPT_TRIANGLE_STRIP, 0, TransparentVertexAlphaCB, EMT_TRANSPARENT_ALPHA_CHANNEL, 0);

		addDummyMaterial(EMT_TRANSPARENT_REFLECTION_2_LAYER);

		// EMT_ONETEXTURE_BLEND
		FragmentShader = OGLES2ShaderPath + "OneTextureBlend.fsh";
		addHighLevelShaderMaterialFromFiles(VertexShader, "main", EVST_VS_2_0, FragmentShader, "main", EPST_PS_2_0, "", "main",
			EGST_GS_4_0, scene::EPT_TRIANGLES, scene::EPT_TRIANGLE_STRIP, 0, OneTextureBlendCB, EMT_ONETEXTURE_BLEND, 0);

		// Drop callbacks.

		SolidCB->drop();
		TransparentAlphaChannelCB->drop();
		TransparentAlphaChannelRefCB->drop();
		TransparentVertexAlphaCB->drop();
		OneTextureBlendCB->drop();

		// Create 2D material renderers

		c8* vs2DData = 0;
		c8* fs2DData = 0;
		loadShaderData(io::path("Renderer2D.vsh"), io::path("Renderer2D.fsh"), &vs2DData, &fs2DData);
		MaterialRenderer2DTexture = new COpenGL3Renderer2D(vs2DData, fs2DData, this, true);
		delete[] vs2DData;
		delete[] fs2DData;
		vs2DData = 0;
		fs2DData = 0;

		loadShaderData(io::path("Renderer2D.vsh"), io::path("Renderer2D_noTex.fsh"), &vs2DData, &fs2DData);
		MaterialRenderer2DNoTexture = new COpenGL3Renderer2D(vs2DData, fs2DData, this, false);
		delete[] vs2DData;
		delete[] fs2DData;
	}

	bool COpenGL3DriverBase::setMaterialTexture(irr::u32 layerIdx, const irr::video::ITexture* texture)
	{
		Material.TextureLayer[layerIdx].Texture = const_cast<ITexture*>(texture); // function uses const-pointer for texture because all draw functions use const-pointers already
		return CacheHandler->getTextureCache().set(0, texture);
	}

	bool COpenGL3DriverBase::beginScene(u16 clearFlag, SColor clearColor, f32 clearDepth, u8 clearStencil, const SExposedVideoData& videoData, core::rect<s32>* sourceRect)
	{
		CNullDriver::beginScene(clearFlag, clearColor, clearDepth, clearStencil, videoData, sourceRect);

		if (ContextManager)
			ContextManager->activateContext(videoData, true);

		clearBuffers(clearFlag, clearColor, clearDepth, clearStencil);

		return true;
	}

	bool COpenGL3DriverBase::endScene()
	{
		CNullDriver::endScene();

		glFlush();

		if (ContextManager)
			return ContextManager->swapBuffers();

		return false;
	}


	//! Returns the transformation set by setTransform
	const core::matrix4& COpenGL3DriverBase::getTransform(E_TRANSFORMATION_STATE state) const
	{
		return Matrices[state];
	}


	//! sets transformation
	void COpenGL3DriverBase::setTransform(E_TRANSFORMATION_STATE state, const core::matrix4& mat)
	{
		Matrices[state] = mat;
		Transformation3DChanged = true;
	}


	bool COpenGL3DriverBase::updateVertexHardwareBuffer(SHWBufferLink_opengl *HWBuffer)
	{
		if (!HWBuffer)
			return false;

		const scene::IMeshBuffer* mb = HWBuffer->MeshBuffer;
		const void* vertices = mb->getVertices();
		const u32 vertexCount = mb->getVertexCount();
		const E_VERTEX_TYPE vType = mb->getVertexType();
		const u32 vertexSize = getVertexPitchFromType(vType);

		const void *buffer = vertices;
		size_t bufferSize = vertexSize * vertexCount;

		//get or create buffer
		bool newBuffer = false;
		if (!HWBuffer->vbo_verticesID)
		{
			glGenBuffers(1, &HWBuffer->vbo_verticesID);
			if (!HWBuffer->vbo_verticesID) return false;
			newBuffer = true;
		}
		else if (HWBuffer->vbo_verticesSize < bufferSize)
		{
			newBuffer = true;
		}

		glBindBuffer(GL_ARRAY_BUFFER, HWBuffer->vbo_verticesID);

		// copy data to graphics card
		if (!newBuffer)
			glBufferSubData(GL_ARRAY_BUFFER, 0, bufferSize, buffer);
		else
		{
			HWBuffer->vbo_verticesSize = bufferSize;

			if (HWBuffer->Mapped_Vertex == scene::EHM_STATIC)
				glBufferData(GL_ARRAY_BUFFER, bufferSize, buffer, GL_STATIC_DRAW);
			else
				glBufferData(GL_ARRAY_BUFFER, bufferSize, buffer, GL_DYNAMIC_DRAW);
		}

		glBindBuffer(GL_ARRAY_BUFFER, 0);

		return (!testGLError(__LINE__));
	}


	bool COpenGL3DriverBase::updateIndexHardwareBuffer(SHWBufferLink_opengl *HWBuffer)
	{
		if (!HWBuffer)
			return false;

		const scene::IMeshBuffer* mb = HWBuffer->MeshBuffer;

		const void* indices = mb->getIndices();
		u32 indexCount = mb->getIndexCount();

		GLenum indexSize;
		switch (mb->getIndexType())
		{
			case(EIT_16BIT):
			{
				indexSize = sizeof(u16);
				break;
			}
			case(EIT_32BIT):
			{
				indexSize = sizeof(u32);
				break;
			}
			default:
			{
				return false;
			}
		}

		//get or create buffer
		bool newBuffer = false;
		if (!HWBuffer->vbo_indicesID)
		{
			glGenBuffers(1, &HWBuffer->vbo_indicesID);
			if (!HWBuffer->vbo_indicesID) return false;
			newBuffer = true;
		}
		else if (HWBuffer->vbo_indicesSize < indexCount*indexSize)
		{
			newBuffer = true;
		}

		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, HWBuffer->vbo_indicesID);

		// copy data to graphics card
		if (!newBuffer)
			glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, 0, indexCount * indexSize, indices);
		else
		{
			HWBuffer->vbo_indicesSize = indexCount * indexSize;

			if (HWBuffer->Mapped_Index == scene::EHM_STATIC)
				glBufferData(GL_ELEMENT_ARRAY_BUFFER, indexCount * indexSize, indices, GL_STATIC_DRAW);
			else
				glBufferData(GL_ELEMENT_ARRAY_BUFFER, indexCount * indexSize, indices, GL_DYNAMIC_DRAW);
		}

		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);

		return (!testGLError(__LINE__));
	}


	//! updates hardware buffer if needed
	bool COpenGL3DriverBase::updateHardwareBuffer(SHWBufferLink *HWBuffer)
	{
		if (!HWBuffer)
			return false;

		if (HWBuffer->Mapped_Vertex != scene::EHM_NEVER)
		{
			if (HWBuffer->ChangedID_Vertex != HWBuffer->MeshBuffer->getChangedID_Vertex()
				|| !static_cast<SHWBufferLink_opengl*>(HWBuffer)->vbo_verticesID)
			{

				HWBuffer->ChangedID_Vertex = HWBuffer->MeshBuffer->getChangedID_Vertex();

				if (!updateVertexHardwareBuffer(static_cast<SHWBufferLink_opengl*>(HWBuffer)))
					return false;
			}
		}

		if (HWBuffer->Mapped_Index != scene::EHM_NEVER)
		{
			if (HWBuffer->ChangedID_Index != HWBuffer->MeshBuffer->getChangedID_Index()
				|| !static_cast<SHWBufferLink_opengl*>(HWBuffer)->vbo_indicesID)
			{

				HWBuffer->ChangedID_Index = HWBuffer->MeshBuffer->getChangedID_Index();

				if (!updateIndexHardwareBuffer((SHWBufferLink_opengl*)HWBuffer))
					return false;
			}
		}

		return true;
	}


	//! Create hardware buffer from meshbuffer
	COpenGL3DriverBase::SHWBufferLink *COpenGL3DriverBase::createHardwareBuffer(const scene::IMeshBuffer* mb)
	{
		if (!mb || (mb->getHardwareMappingHint_Index() == scene::EHM_NEVER && mb->getHardwareMappingHint_Vertex() == scene::EHM_NEVER))
			return 0;

		SHWBufferLink_opengl *HWBuffer = new SHWBufferLink_opengl(mb);

		//add to map
		HWBuffer->listPosition = HWBufferList.insert(HWBufferList.end(), HWBuffer);

		HWBuffer->ChangedID_Vertex = HWBuffer->MeshBuffer->getChangedID_Vertex();
		HWBuffer->ChangedID_Index = HWBuffer->MeshBuffer->getChangedID_Index();
		HWBuffer->Mapped_Vertex = mb->getHardwareMappingHint_Vertex();
		HWBuffer->Mapped_Index = mb->getHardwareMappingHint_Index();
		HWBuffer->vbo_verticesID = 0;
		HWBuffer->vbo_indicesID = 0;
		HWBuffer->vbo_verticesSize = 0;
		HWBuffer->vbo_indicesSize = 0;

		if (!updateHardwareBuffer(HWBuffer))
		{
			deleteHardwareBuffer(HWBuffer);
			return 0;
		}

		return HWBuffer;
	}


	void COpenGL3DriverBase::deleteHardwareBuffer(SHWBufferLink *_HWBuffer)
	{
		if (!_HWBuffer)
			return;

		SHWBufferLink_opengl *HWBuffer = static_cast<SHWBufferLink_opengl*>(_HWBuffer);
		if (HWBuffer->vbo_verticesID)
		{
			glDeleteBuffers(1, &HWBuffer->vbo_verticesID);
			HWBuffer->vbo_verticesID = 0;
		}
		if (HWBuffer->vbo_indicesID)
		{
			glDeleteBuffers(1, &HWBuffer->vbo_indicesID);
			HWBuffer->vbo_indicesID = 0;
		}

		CNullDriver::deleteHardwareBuffer(_HWBuffer);
	}


	//! Draw hardware buffer
	void COpenGL3DriverBase::drawHardwareBuffer(SHWBufferLink *_HWBuffer)
	{
		if (!_HWBuffer)
			return;

		SHWBufferLink_opengl *HWBuffer = static_cast<SHWBufferLink_opengl*>(_HWBuffer);

		updateHardwareBuffer(HWBuffer); //check if update is needed

		const scene::IMeshBuffer* mb = HWBuffer->MeshBuffer;
		const void *vertices = mb->getVertices();
		const void *indexList = mb->getIndices();

		if (HWBuffer->Mapped_Vertex != scene::EHM_NEVER)
		{
			glBindBuffer(GL_ARRAY_BUFFER, HWBuffer->vbo_verticesID);
			vertices = 0;
		}

		if (HWBuffer->Mapped_Index != scene::EHM_NEVER)
		{
			glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, HWBuffer->vbo_indicesID);
			indexList = 0;
		}


		drawVertexPrimitiveList(vertices, mb->getVertexCount(),
				indexList, mb->getPrimitiveCount(),
				mb->getVertexType(), mb->getPrimitiveType(),
				mb->getIndexType());

		if (HWBuffer->Mapped_Vertex != scene::EHM_NEVER)
			glBindBuffer(GL_ARRAY_BUFFER, 0);

		if (HWBuffer->Mapped_Index != scene::EHM_NEVER)
			glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
	}


	IRenderTarget* COpenGL3DriverBase::addRenderTarget()
	{
		COpenGL3RenderTarget* renderTarget = new COpenGL3RenderTarget(this);
		RenderTargets.push_back(renderTarget);

		return renderTarget;
	}


	// small helper function to create vertex buffer object adress offsets
	static inline u8* buffer_offset(const long offset)
	{
		return ((u8*)0 + offset);
	}


	//! draws a vertex primitive list
	void COpenGL3DriverBase::drawVertexPrimitiveList(const void* vertices, u32 vertexCount,
			const void* indexList, u32 primitiveCount,
			E_VERTEX_TYPE vType, scene::E_PRIMITIVE_TYPE pType, E_INDEX_TYPE iType)
	{
		if (!primitiveCount || !vertexCount)
			return;

		if (!checkPrimitiveCount(primitiveCount))
			return;

		CNullDriver::drawVertexPrimitiveList(vertices, vertexCount, indexList, primitiveCount, vType, pType, iType);

		setRenderStates3DMode();

		auto &vTypeDesc = getVertexTypeDescription(vType);
		beginDraw(vTypeDesc, reinterpret_cast<uintptr_t>(vertices));
		GLenum indexSize = 0;

		switch (iType)
		{
			case(EIT_16BIT):
			{
				indexSize = GL_UNSIGNED_SHORT;
				break;
			}
			case(EIT_32BIT):
			{
#ifdef GL_OES_element_index_uint
#ifndef GL_UNSIGNED_INT
#define GL_UNSIGNED_INT 0x1405
#endif
				if (FeatureAvailable[COGLESCoreExtensionHandler::IRR_GL_OES_element_index_uint])
					indexSize = GL_UNSIGNED_INT;
				else
#endif
					indexSize = GL_UNSIGNED_SHORT;
				break;
			}
		}

		switch (pType)
		{
			case scene::EPT_POINTS:
			case scene::EPT_POINT_SPRITES:
				glDrawArrays(GL_POINTS, 0, primitiveCount);
				break;
			case scene::EPT_LINE_STRIP:
				glDrawElements(GL_LINE_STRIP, primitiveCount + 1, indexSize, indexList);
				break;
			case scene::EPT_LINE_LOOP:
				glDrawElements(GL_LINE_LOOP, primitiveCount, indexSize, indexList);
				break;
			case scene::EPT_LINES:
				glDrawElements(GL_LINES, primitiveCount*2, indexSize, indexList);
				break;
			case scene::EPT_TRIANGLE_STRIP:
				glDrawElements(GL_TRIANGLE_STRIP, primitiveCount + 2, indexSize, indexList);
				break;
			case scene::EPT_TRIANGLE_FAN:
				glDrawElements(GL_TRIANGLE_FAN, primitiveCount + 2, indexSize, indexList);
				break;
			case scene::EPT_TRIANGLES:
				glDrawElements((LastMaterial.Wireframe) ? GL_LINES : (LastMaterial.PointCloud) ? GL_POINTS : GL_TRIANGLES, primitiveCount*3, indexSize, indexList);
				break;
			default:
				break;
		}

		endDraw(vTypeDesc);
	}


	void COpenGL3DriverBase::draw2DImage(const video::ITexture* texture, const core::position2d<s32>& destPos,
		const core::rect<s32>& sourceRect, const core::rect<s32>* clipRect, SColor color,
		bool useAlphaChannelOfTexture)
	{
		if (!texture)
			return;

		if (!sourceRect.isValid())
			return;

		SColor colors[4] = {color, color, color, color};
		draw2DImage(texture, {destPos, sourceRect.getSize()}, sourceRect, clipRect, colors, useAlphaChannelOfTexture);
	}


	void COpenGL3DriverBase::draw2DImage(const video::ITexture* texture, const core::rect<s32>& destRect,
		const core::rect<s32>& sourceRect, const core::rect<s32>* clipRect,
		const video::SColor* const colors, bool useAlphaChannelOfTexture)
	{
		if (!texture)
			return;

		// texcoords need to be flipped horizontally for RTTs
		const bool isRTT = texture->isRenderTarget();
		const core::dimension2du& ss = texture->getOriginalSize();
		const f32 invW = 1.f / static_cast<f32>(ss.Width);
		const f32 invH = 1.f / static_cast<f32>(ss.Height);
		const core::rect<f32> tcoords(
			sourceRect.UpperLeftCorner.X * invW,
			(isRTT ? sourceRect.LowerRightCorner.Y : sourceRect.UpperLeftCorner.Y) * invH,
			sourceRect.LowerRightCorner.X * invW,
			(isRTT ? sourceRect.UpperLeftCorner.Y : sourceRect.LowerRightCorner.Y) *invH);

		const video::SColor temp[4] =
		{
			0xFFFFFFFF,
			0xFFFFFFFF,
			0xFFFFFFFF,
			0xFFFFFFFF
		};

		const video::SColor* const useColor = colors ? colors : temp;

		chooseMaterial2D();
		if (!setMaterialTexture(0, texture ))
			return;

		setRenderStates2DMode(useColor[0].getAlpha() < 255 || useColor[1].getAlpha() < 255 ||
			useColor[2].getAlpha() < 255 || useColor[3].getAlpha() < 255,
			true, useAlphaChannelOfTexture);

		const core::dimension2d<u32>& renderTargetSize = getCurrentRenderTargetSize();

		if (clipRect)
		{
			if (!clipRect->isValid())
				return;

			glEnable(GL_SCISSOR_TEST);
			glScissor(clipRect->UpperLeftCorner.X, renderTargetSize.Height - clipRect->LowerRightCorner.Y,
				clipRect->getWidth(), clipRect->getHeight());
		}

		f32 left = (f32)destRect.UpperLeftCorner.X / (f32)renderTargetSize.Width * 2.f - 1.f;
		f32 right = (f32)destRect.LowerRightCorner.X / (f32)renderTargetSize.Width * 2.f - 1.f;
		f32 down = 2.f - (f32)destRect.LowerRightCorner.Y / (f32)renderTargetSize.Height * 2.f - 1.f;
		f32 top = 2.f - (f32)destRect.UpperLeftCorner.Y / (f32)renderTargetSize.Height * 2.f - 1.f;

		S3DVertex vertices[4];
		vertices[0] = S3DVertex(left, top, 0, 0, 0, 1, useColor[0], tcoords.UpperLeftCorner.X, tcoords.UpperLeftCorner.Y);
		vertices[1] = S3DVertex(right, top, 0, 0, 0, 1, useColor[3], tcoords.LowerRightCorner.X, tcoords.UpperLeftCorner.Y);
		vertices[2] = S3DVertex(right, down, 0, 0, 0, 1, useColor[2], tcoords.LowerRightCorner.X, tcoords.LowerRightCorner.Y);
		vertices[3] = S3DVertex(left, down, 0, 0, 0, 1, useColor[1], tcoords.UpperLeftCorner.X, tcoords.LowerRightCorner.Y);

		drawQuad(vt2DImage, vertices);

		if (clipRect)
			glDisable(GL_SCISSOR_TEST);

		testGLError(__LINE__);
	}

	void COpenGL3DriverBase::draw2DImage(const video::ITexture* texture, u32 layer, bool flip)
	{
		if (!texture)
			return;

		chooseMaterial2D();
		if (!setMaterialTexture(0, texture ))
			return;

		setRenderStates2DMode(false, true, true);

		S3DVertex quad2DVertices[4];

		quad2DVertices[0].Pos = core::vector3df(-1.f, 1.f, 0.f);
		quad2DVertices[1].Pos = core::vector3df(1.f, 1.f, 0.f);
		quad2DVertices[2].Pos = core::vector3df(1.f, -1.f, 0.f);
		quad2DVertices[3].Pos = core::vector3df(-1.f, -1.f, 0.f);

		f32 modificator = (flip) ? 1.f : 0.f;

		quad2DVertices[0].TCoords = core::vector2df(0.f, 0.f + modificator);
		quad2DVertices[1].TCoords = core::vector2df(1.f, 0.f + modificator);
		quad2DVertices[2].TCoords = core::vector2df(1.f, 1.f - modificator);
		quad2DVertices[3].TCoords = core::vector2df(0.f, 1.f - modificator);

		quad2DVertices[0].Color = SColor(0xFFFFFFFF);
		quad2DVertices[1].Color = SColor(0xFFFFFFFF);
		quad2DVertices[2].Color = SColor(0xFFFFFFFF);
		quad2DVertices[3].Color = SColor(0xFFFFFFFF);

		drawQuad(vt2DImage, quad2DVertices);
	}

	void COpenGL3DriverBase::draw2DImageBatch(const video::ITexture* texture,
			const core::array<core::position2d<s32> >& positions,
			const core::array<core::rect<s32> >& sourceRects,
			const core::rect<s32>* clipRect,
			SColor color, bool useAlphaChannelOfTexture)
	{
		if (!texture)
			return;

		chooseMaterial2D();
		if (!setMaterialTexture(0, texture))
			return;

		setRenderStates2DMode(color.getAlpha() < 255, true, useAlphaChannelOfTexture);

		const core::dimension2d<u32>& renderTargetSize = getCurrentRenderTargetSize();

		if (clipRect)
		{
			if (!clipRect->isValid())
				return;

			glEnable(GL_SCISSOR_TEST);
			glScissor(clipRect->UpperLeftCorner.X, renderTargetSize.Height - clipRect->LowerRightCorner.Y,
					clipRect->getWidth(), clipRect->getHeight());
		}

		const irr::u32 drawCount = core::min_<u32>(positions.size(), sourceRects.size());
		assert(6 * drawCount <= QuadIndexCount); // FIXME split the batch? or let it crash?

		core::array<S3DVertex> vtx(drawCount * 4);

		for (u32 i = 0; i < drawCount; i++)
		{
			core::position2d<s32> targetPos = positions[i];
			core::position2d<s32> sourcePos = sourceRects[i].UpperLeftCorner;
			// This needs to be signed as it may go negative.
			core::dimension2d<s32> sourceSize(sourceRects[i].getSize());

			// now draw it.

			core::rect<f32> tcoords;
			tcoords.UpperLeftCorner.X = (((f32)sourcePos.X)) / texture->getOriginalSize().Width ;
			tcoords.UpperLeftCorner.Y = (((f32)sourcePos.Y)) / texture->getOriginalSize().Height;
			tcoords.LowerRightCorner.X = tcoords.UpperLeftCorner.X + ((f32)(sourceSize.Width) / texture->getOriginalSize().Width);
			tcoords.LowerRightCorner.Y = tcoords.UpperLeftCorner.Y + ((f32)(sourceSize.Height) / texture->getOriginalSize().Height);

			const core::rect<s32> poss(targetPos, sourceSize);

			f32 left = (f32)poss.UpperLeftCorner.X / (f32)renderTargetSize.Width * 2.f - 1.f;
			f32 right = (f32)poss.LowerRightCorner.X / (f32)renderTargetSize.Width * 2.f - 1.f;
			f32 down = 2.f - (f32)poss.LowerRightCorner.Y / (f32)renderTargetSize.Height * 2.f - 1.f;
			f32 top = 2.f - (f32)poss.UpperLeftCorner.Y / (f32)renderTargetSize.Height * 2.f - 1.f;

			vtx.push_back(S3DVertex(left, top, 0.0f,
					0.0f, 0.0f, 0.0f, color,
					tcoords.UpperLeftCorner.X, tcoords.UpperLeftCorner.Y));
			vtx.push_back(S3DVertex(right, top, 0.0f,
					0.0f, 0.0f, 0.0f, color,
					tcoords.LowerRightCorner.X, tcoords.UpperLeftCorner.Y));
			vtx.push_back(S3DVertex(right, down, 0.0f,
					0.0f, 0.0f, 0.0f, color,
					tcoords.LowerRightCorner.X, tcoords.LowerRightCorner.Y));
			vtx.push_back(S3DVertex(left, down, 0.0f,
					0.0f, 0.0f, 0.0f, color,
					tcoords.UpperLeftCorner.X, tcoords.LowerRightCorner.Y));
		}

		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, QuadIndexBuffer);
		drawElements(GL_TRIANGLES, vt2DImage, vtx.const_pointer(), vtx.size(), 0, 6 * drawCount);
		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);

		if (clipRect)
			glDisable(GL_SCISSOR_TEST);
	}


	//! draw a 2d rectangle
	void COpenGL3DriverBase::draw2DRectangle(SColor color,
			const core::rect<s32>& position,
			const core::rect<s32>* clip)
	{
		chooseMaterial2D();
		setMaterialTexture(0, 0);

		setRenderStates2DMode(color.getAlpha() < 255, false, false);

		core::rect<s32> pos = position;

		if (clip)
			pos.clipAgainst(*clip);

		if (!pos.isValid())
			return;

		const core::dimension2d<u32>& renderTargetSize = getCurrentRenderTargetSize();

		f32 left = (f32)pos.UpperLeftCorner.X / (f32)renderTargetSize.Width * 2.f - 1.f;
		f32 right = (f32)pos.LowerRightCorner.X / (f32)renderTargetSize.Width * 2.f - 1.f;
		f32 down = 2.f - (f32)pos.LowerRightCorner.Y / (f32)renderTargetSize.Height * 2.f - 1.f;
		f32 top = 2.f - (f32)pos.UpperLeftCorner.Y / (f32)renderTargetSize.Height * 2.f - 1.f;

		S3DVertex vertices[4];
		vertices[0] = S3DVertex(left, top, 0, 0, 0, 1, color, 0, 0);
		vertices[1] = S3DVertex(right, top, 0, 0, 0, 1, color, 0, 0);
		vertices[2] = S3DVertex(right, down, 0, 0, 0, 1, color, 0, 0);
		vertices[3] = S3DVertex(left, down, 0, 0, 0, 1, color, 0, 0);

		drawQuad(vtPrimitive, vertices);
	}


	//! draw an 2d rectangle
	void COpenGL3DriverBase::draw2DRectangle(const core::rect<s32>& position,
			SColor colorLeftUp, SColor colorRightUp,
			SColor colorLeftDown, SColor colorRightDown,
			const core::rect<s32>* clip)
	{
		core::rect<s32> pos = position;

		if (clip)
			pos.clipAgainst(*clip);

		if (!pos.isValid())
			return;

		chooseMaterial2D();
		setMaterialTexture(0, 0);

		setRenderStates2DMode(colorLeftUp.getAlpha() < 255 ||
				colorRightUp.getAlpha() < 255 ||
				colorLeftDown.getAlpha() < 255 ||
				colorRightDown.getAlpha() < 255, false, false);

		const core::dimension2d<u32>& renderTargetSize = getCurrentRenderTargetSize();

		f32 left = (f32)pos.UpperLeftCorner.X / (f32)renderTargetSize.Width * 2.f - 1.f;
		f32 right = (f32)pos.LowerRightCorner.X / (f32)renderTargetSize.Width * 2.f - 1.f;
		f32 down = 2.f - (f32)pos.LowerRightCorner.Y / (f32)renderTargetSize.Height * 2.f - 1.f;
		f32 top = 2.f - (f32)pos.UpperLeftCorner.Y / (f32)renderTargetSize.Height * 2.f - 1.f;

		S3DVertex vertices[4];
		vertices[0] = S3DVertex(left, top, 0, 0, 0, 1, colorLeftUp, 0, 0);
		vertices[1] = S3DVertex(right, top, 0, 0, 0, 1, colorRightUp, 0, 0);
		vertices[2] = S3DVertex(right, down, 0, 0, 0, 1, colorRightDown, 0, 0);
		vertices[3] = S3DVertex(left, down, 0, 0, 0, 1, colorLeftDown, 0, 0);

		drawQuad(vtPrimitive, vertices);
	}


	//! Draws a 2d line.
	void COpenGL3DriverBase::draw2DLine(const core::position2d<s32>& start,
			const core::position2d<s32>& end, SColor color)
	{
		if (start==end)
			drawPixel(start.X, start.Y, color);
		else
		{
			chooseMaterial2D();
			setMaterialTexture(0, 0);

			setRenderStates2DMode(color.getAlpha() < 255, false, false);

			const core::dimension2d<u32>& renderTargetSize = getCurrentRenderTargetSize();

			f32 startX = (f32)start.X / (f32)renderTargetSize.Width * 2.f - 1.f;
			f32 endX = (f32)end.X / (f32)renderTargetSize.Width * 2.f - 1.f;
			f32 startY = 2.f - (f32)start.Y / (f32)renderTargetSize.Height * 2.f - 1.f;
			f32 endY = 2.f - (f32)end.Y / (f32)renderTargetSize.Height * 2.f - 1.f;

			S3DVertex vertices[2];
			vertices[0] = S3DVertex(startX, startY, 0, 0, 0, 1, color, 0, 0);
			vertices[1] = S3DVertex(endX, endY, 0, 0, 0, 1, color, 1, 1);

			drawArrays(GL_LINES, vtPrimitive, vertices, 2);
		}
	}


	//! Draws a pixel
	void COpenGL3DriverBase::drawPixel(u32 x, u32 y, const SColor &color)
	{
		const core::dimension2d<u32>& renderTargetSize = getCurrentRenderTargetSize();
		if (x > (u32)renderTargetSize.Width || y > (u32)renderTargetSize.Height)
			return;

		chooseMaterial2D();
		setMaterialTexture(0, 0);

		setRenderStates2DMode(color.getAlpha() < 255, false, false);

		f32 X = (f32)x / (f32)renderTargetSize.Width * 2.f - 1.f;
		f32 Y = 2.f - (f32)y / (f32)renderTargetSize.Height * 2.f - 1.f;

		S3DVertex vertices[1];
		vertices[0] = S3DVertex(X, Y, 0, 0, 0, 1, color, 0, 0);

		drawArrays(GL_POINTS, vtPrimitive, vertices, 1);
	}

	void COpenGL3DriverBase::drawQuad(const VertexType &vertexType, const S3DVertex (&vertices)[4])
	{
		drawArrays(GL_TRIANGLE_FAN, vertexType, vertices, 4);
	}

	void COpenGL3DriverBase::drawArrays(GLenum primitiveType, const VertexType &vertexType, const void *vertices, int vertexCount)
	{
		beginDraw(vertexType, reinterpret_cast<uintptr_t>(vertices));
		glDrawArrays(primitiveType, 0, vertexCount);
		endDraw(vertexType);
	}

	void COpenGL3DriverBase::drawElements(GLenum primitiveType, const VertexType &vertexType, const void *vertices, int vertexCount, const u16 *indices, int indexCount)
	{
		beginDraw(vertexType, reinterpret_cast<uintptr_t>(vertices));
		glDrawRangeElements(primitiveType, 0, vertexCount - 1, indexCount, GL_UNSIGNED_SHORT, indices);
		endDraw(vertexType);
	}

	void COpenGL3DriverBase::beginDraw(const VertexType &vertexType, uintptr_t verticesBase)
	{
		for (auto attr: vertexType) {
			glEnableVertexAttribArray(attr.Index);
			switch (attr.mode) {
			case VertexAttribute::Mode::Regular: glVertexAttribPointer(attr.Index, attr.ComponentCount, attr.ComponentType, GL_FALSE, vertexType.VertexSize, reinterpret_cast<void *>(verticesBase + attr.Offset)); break;
			case VertexAttribute::Mode::Normalized: glVertexAttribPointer(attr.Index, attr.ComponentCount, attr.ComponentType, GL_TRUE, vertexType.VertexSize, reinterpret_cast<void *>(verticesBase + attr.Offset)); break;
			case VertexAttribute::Mode::Integral: glVertexAttribIPointer(attr.Index, attr.ComponentCount, attr.ComponentType, vertexType.VertexSize, reinterpret_cast<void *>(verticesBase + attr.Offset)); break;
			}
		}
	}

	void COpenGL3DriverBase::endDraw(const VertexType &vertexType)
	{
		for (auto attr: vertexType)
			glDisableVertexAttribArray(attr.Index);
	}

	ITexture* COpenGL3DriverBase::createDeviceDependentTexture(const io::path& name, IImage* image)
	{
		core::array<IImage*> imageArray(1);
		imageArray.push_back(image);

		COpenGL3Texture* texture = new COpenGL3Texture(name, imageArray, ETT_2D, this);

		return texture;
	}

	ITexture* COpenGL3DriverBase::createDeviceDependentTextureCubemap(const io::path& name, const core::array<IImage*>& image)
	{
		COpenGL3Texture* texture = new COpenGL3Texture(name, image, ETT_CUBEMAP, this);

		return texture;
	}

	//! Sets a material.
	void COpenGL3DriverBase::setMaterial(const SMaterial& material)
	{
		Material = material;
		OverrideMaterial.apply(Material);

		for (u32 i = 0; i < Feature.MaxTextureUnits; ++i)
		{
			CacheHandler->getTextureCache().set(i, material.getTexture(i));
			setTransform((E_TRANSFORMATION_STATE)(ETS_TEXTURE_0 + i), material.getTextureMatrix(i));
		}
	}

	//! prints error if an error happened.
	bool COpenGL3DriverBase::testGLError(int code)
	{
#ifdef _DEBUG
		GLenum g = glGetError();
		switch (g)
		{
			case GL_NO_ERROR:
				return false;
			case GL_INVALID_ENUM:
				os::Printer::log("GL_INVALID_ENUM", core::stringc(code).c_str(), ELL_ERROR);
				break;
			case GL_INVALID_VALUE:
				os::Printer::log("GL_INVALID_VALUE", core::stringc(code).c_str(), ELL_ERROR);
				break;
			case GL_INVALID_OPERATION:
				os::Printer::log("GL_INVALID_OPERATION", core::stringc(code).c_str(), ELL_ERROR);
				break;
			case GL_OUT_OF_MEMORY:
				os::Printer::log("GL_OUT_OF_MEMORY", core::stringc(code).c_str(), ELL_ERROR);
				break;
		};
		return true;
#else
		return false;
#endif
	}

	//! prints error if an error happened.
	bool COpenGL3DriverBase::testEGLError()
	{
#if defined(EGL_VERSION_1_0) && defined(_DEBUG)
		EGLint g = eglGetError();
		switch (g)
		{
			case EGL_SUCCESS:
				return false;
			case EGL_NOT_INITIALIZED :
				os::Printer::log("Not Initialized", ELL_ERROR);
				break;
			case EGL_BAD_ACCESS:
				os::Printer::log("Bad Access", ELL_ERROR);
				break;
			case EGL_BAD_ALLOC:
				os::Printer::log("Bad Alloc", ELL_ERROR);
				break;
			case EGL_BAD_ATTRIBUTE:
				os::Printer::log("Bad Attribute", ELL_ERROR);
				break;
			case EGL_BAD_CONTEXT:
				os::Printer::log("Bad Context", ELL_ERROR);
				break;
			case EGL_BAD_CONFIG:
				os::Printer::log("Bad Config", ELL_ERROR);
				break;
			case EGL_BAD_CURRENT_SURFACE:
				os::Printer::log("Bad Current Surface", ELL_ERROR);
				break;
			case EGL_BAD_DISPLAY:
				os::Printer::log("Bad Display", ELL_ERROR);
				break;
			case EGL_BAD_SURFACE:
				os::Printer::log("Bad Surface", ELL_ERROR);
				break;
			case EGL_BAD_MATCH:
				os::Printer::log("Bad Match", ELL_ERROR);
				break;
			case EGL_BAD_PARAMETER:
				os::Printer::log("Bad Parameter", ELL_ERROR);
				break;
			case EGL_BAD_NATIVE_PIXMAP:
				os::Printer::log("Bad Native Pixmap", ELL_ERROR);
				break;
			case EGL_BAD_NATIVE_WINDOW:
				os::Printer::log("Bad Native Window", ELL_ERROR);
				break;
			case EGL_CONTEXT_LOST:
				os::Printer::log("Context Lost", ELL_ERROR);
				break;
		};
		return true;
#else
		return false;
#endif
	}


	void COpenGL3DriverBase::setRenderStates3DMode()
	{
		if ( LockRenderStateMode )
			return;

		if (CurrentRenderMode != ERM_3D)
		{
			// Reset Texture Stages
			CacheHandler->setBlend(false);
			CacheHandler->setBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

			ResetRenderStates = true;
		}

		if (ResetRenderStates || LastMaterial != Material)
		{
			// unset old material

			// unset last 3d material
			if (CurrentRenderMode == ERM_2D && MaterialRenderer2DActive)
			{
				MaterialRenderer2DActive->OnUnsetMaterial();
				MaterialRenderer2DActive = 0;
			}
			else if (LastMaterial.MaterialType != Material.MaterialType &&
					static_cast<u32>(LastMaterial.MaterialType) < MaterialRenderers.size())
				MaterialRenderers[LastMaterial.MaterialType].Renderer->OnUnsetMaterial();

			// set new material.
			if (static_cast<u32>(Material.MaterialType) < MaterialRenderers.size())
				MaterialRenderers[Material.MaterialType].Renderer->OnSetMaterial(
					Material, LastMaterial, ResetRenderStates, this);

			LastMaterial = Material;
			CacheHandler->correctCacheMaterial(LastMaterial);
			ResetRenderStates = false;
		}

		if (static_cast<u32>(Material.MaterialType) < MaterialRenderers.size())
			MaterialRenderers[Material.MaterialType].Renderer->OnRender(this, video::EVT_STANDARD);

		CurrentRenderMode = ERM_3D;
	}

	//! Can be called by an IMaterialRenderer to make its work easier.
	void COpenGL3DriverBase::setBasicRenderStates(const SMaterial& material, const SMaterial& lastmaterial, bool resetAllRenderStates)
	{
		// ZBuffer
		switch (material.ZBuffer)
		{
			case ECFN_DISABLED:
				CacheHandler->setDepthTest(false);
				break;
			case ECFN_LESSEQUAL:
				CacheHandler->setDepthTest(true);
				CacheHandler->setDepthFunc(GL_LEQUAL);
				break;
			case ECFN_EQUAL:
				CacheHandler->setDepthTest(true);
				CacheHandler->setDepthFunc(GL_EQUAL);
				break;
			case ECFN_LESS:
				CacheHandler->setDepthTest(true);
				CacheHandler->setDepthFunc(GL_LESS);
				break;
			case ECFN_NOTEQUAL:
				CacheHandler->setDepthTest(true);
				CacheHandler->setDepthFunc(GL_NOTEQUAL);
				break;
			case ECFN_GREATEREQUAL:
				CacheHandler->setDepthTest(true);
				CacheHandler->setDepthFunc(GL_GEQUAL);
				break;
			case ECFN_GREATER:
				CacheHandler->setDepthTest(true);
				CacheHandler->setDepthFunc(GL_GREATER);
				break;
			case ECFN_ALWAYS:
				CacheHandler->setDepthTest(true);
				CacheHandler->setDepthFunc(GL_ALWAYS);
				break;
			case ECFN_NEVER:
				CacheHandler->setDepthTest(true);
				CacheHandler->setDepthFunc(GL_NEVER);
				break;
			default:
				break;
		}

		// ZWrite
		if (getWriteZBuffer(material))
		{
			CacheHandler->setDepthMask(true);
		}
		else
		{
			CacheHandler->setDepthMask(false);
		}

		// Back face culling
		if ((material.FrontfaceCulling) && (material.BackfaceCulling))
		{
			CacheHandler->setCullFaceFunc(GL_FRONT_AND_BACK);
			CacheHandler->setCullFace(true);
		}
		else if (material.BackfaceCulling)
		{
			CacheHandler->setCullFaceFunc(GL_BACK);
			CacheHandler->setCullFace(true);
		}
		else if (material.FrontfaceCulling)
		{
			CacheHandler->setCullFaceFunc(GL_FRONT);
			CacheHandler->setCullFace(true);
		}
		else
		{
			CacheHandler->setCullFace(false);
		}

		// Color Mask
		CacheHandler->setColorMask(material.ColorMask);

		// Blend Equation
		if (material.BlendOperation == EBO_NONE)
			CacheHandler->setBlend(false);
		else
		{
			CacheHandler->setBlend(true);

			switch (material.BlendOperation)
			{
			case EBO_ADD:
				CacheHandler->setBlendEquation(GL_FUNC_ADD);
				break;
			case EBO_SUBTRACT:
				CacheHandler->setBlendEquation(GL_FUNC_SUBTRACT);
				break;
			case EBO_REVSUBTRACT:
				CacheHandler->setBlendEquation(GL_FUNC_REVERSE_SUBTRACT);
				break;
			default:
				break;
			}
		}

		// Blend Factor
		if (IR(material.BlendFactor) & 0xFFFFFFFF	// TODO: why the & 0xFFFFFFFF?
			&& material.MaterialType != EMT_ONETEXTURE_BLEND
		)
		{
		    E_BLEND_FACTOR srcRGBFact = EBF_ZERO;
		    E_BLEND_FACTOR dstRGBFact = EBF_ZERO;
		    E_BLEND_FACTOR srcAlphaFact = EBF_ZERO;
		    E_BLEND_FACTOR dstAlphaFact = EBF_ZERO;
		    E_MODULATE_FUNC modulo = EMFN_MODULATE_1X;
		    u32 alphaSource = 0;

		    unpack_textureBlendFuncSeparate(srcRGBFact, dstRGBFact, srcAlphaFact, dstAlphaFact, modulo, alphaSource, material.BlendFactor);

			CacheHandler->setBlendFuncSeparate(getGLBlend(srcRGBFact), getGLBlend(dstRGBFact),
				getGLBlend(srcAlphaFact), getGLBlend(dstAlphaFact));
		}

		// TODO: Polygon Offset. Not sure if it was left out deliberately or if it won't work with this driver.

		if (resetAllRenderStates || lastmaterial.Thickness != material.Thickness)
			glLineWidth(core::clamp(static_cast<GLfloat>(material.Thickness), DimAliasedLine[0], DimAliasedLine[1]));

		// Anti aliasing
		if (resetAllRenderStates || lastmaterial.AntiAliasing != material.AntiAliasing)
		{
			if (material.AntiAliasing & EAAM_ALPHA_TO_COVERAGE)
				glEnable(GL_SAMPLE_ALPHA_TO_COVERAGE);
			else if (lastmaterial.AntiAliasing & EAAM_ALPHA_TO_COVERAGE)
				glDisable(GL_SAMPLE_ALPHA_TO_COVERAGE);
		}

		// Texture parameters
		setTextureRenderStates(material, resetAllRenderStates);
	}

	//! Compare in SMaterial doesn't check texture parameters, so we should call this on each OnRender call.
	void COpenGL3DriverBase::setTextureRenderStates(const SMaterial& material, bool resetAllRenderstates)
	{
		// Set textures to TU/TIU and apply filters to them

		for (s32 i = Feature.MaxTextureUnits - 1; i >= 0; --i)
		{
			const COpenGL3Texture* tmpTexture = CacheHandler->getTextureCache()[i];

			if (!tmpTexture)
				continue;

			GLenum tmpTextureType = tmpTexture->getOpenGLTextureType();

			CacheHandler->setActiveTexture(GL_TEXTURE0 + i);

			if (resetAllRenderstates)
				tmpTexture->getStatesCache().IsCached = false;

			if (!tmpTexture->getStatesCache().IsCached || material.TextureLayer[i].BilinearFilter != tmpTexture->getStatesCache().BilinearFilter ||
				material.TextureLayer[i].TrilinearFilter != tmpTexture->getStatesCache().TrilinearFilter)
			{
				glTexParameteri(tmpTextureType, GL_TEXTURE_MAG_FILTER,
					(material.TextureLayer[i].BilinearFilter || material.TextureLayer[i].TrilinearFilter) ? GL_LINEAR : GL_NEAREST);

				tmpTexture->getStatesCache().BilinearFilter = material.TextureLayer[i].BilinearFilter;
				tmpTexture->getStatesCache().TrilinearFilter = material.TextureLayer[i].TrilinearFilter;
			}

			if (material.UseMipMaps && tmpTexture->hasMipMaps())
			{
				if (!tmpTexture->getStatesCache().IsCached || material.TextureLayer[i].BilinearFilter != tmpTexture->getStatesCache().BilinearFilter ||
					material.TextureLayer[i].TrilinearFilter != tmpTexture->getStatesCache().TrilinearFilter || !tmpTexture->getStatesCache().MipMapStatus)
				{
					glTexParameteri(tmpTextureType, GL_TEXTURE_MIN_FILTER,
						material.TextureLayer[i].TrilinearFilter ? GL_LINEAR_MIPMAP_LINEAR :
						material.TextureLayer[i].BilinearFilter ? GL_LINEAR_MIPMAP_NEAREST :
						GL_NEAREST_MIPMAP_NEAREST);

					tmpTexture->getStatesCache().BilinearFilter = material.TextureLayer[i].BilinearFilter;
					tmpTexture->getStatesCache().TrilinearFilter = material.TextureLayer[i].TrilinearFilter;
					tmpTexture->getStatesCache().MipMapStatus = true;
				}
			}
			else
			{
				if (!tmpTexture->getStatesCache().IsCached || material.TextureLayer[i].BilinearFilter != tmpTexture->getStatesCache().BilinearFilter ||
					material.TextureLayer[i].TrilinearFilter != tmpTexture->getStatesCache().TrilinearFilter || tmpTexture->getStatesCache().MipMapStatus)
				{
					glTexParameteri(tmpTextureType, GL_TEXTURE_MIN_FILTER,
						(material.TextureLayer[i].BilinearFilter || material.TextureLayer[i].TrilinearFilter) ? GL_LINEAR : GL_NEAREST);

					tmpTexture->getStatesCache().BilinearFilter = material.TextureLayer[i].BilinearFilter;
					tmpTexture->getStatesCache().TrilinearFilter = material.TextureLayer[i].TrilinearFilter;
					tmpTexture->getStatesCache().MipMapStatus = false;
				}
			}

	#ifdef GL_EXT_texture_filter_anisotropic
			if (FeatureAvailable[COGLESCoreExtensionHandler::IRR_GL_EXT_texture_filter_anisotropic] &&
				(!tmpTexture->getStatesCache().IsCached || material.TextureLayer[i].AnisotropicFilter != tmpTexture->getStatesCache().AnisotropicFilter))
			{
				glTexParameteri(tmpTextureType, GL_TEXTURE_MAX_ANISOTROPY_EXT,
					material.TextureLayer[i].AnisotropicFilter>1 ? core::min_(MaxAnisotropy, material.TextureLayer[i].AnisotropicFilter) : 1);

				tmpTexture->getStatesCache().AnisotropicFilter = material.TextureLayer[i].AnisotropicFilter;
			}
	#endif

			if (!tmpTexture->getStatesCache().IsCached || material.TextureLayer[i].TextureWrapU != tmpTexture->getStatesCache().WrapU)
			{
				glTexParameteri(tmpTextureType, GL_TEXTURE_WRAP_S, getTextureWrapMode(material.TextureLayer[i].TextureWrapU));
				tmpTexture->getStatesCache().WrapU = material.TextureLayer[i].TextureWrapU;
			}

			if (!tmpTexture->getStatesCache().IsCached || material.TextureLayer[i].TextureWrapV != tmpTexture->getStatesCache().WrapV)
			{
				glTexParameteri(tmpTextureType, GL_TEXTURE_WRAP_T, getTextureWrapMode(material.TextureLayer[i].TextureWrapV));
				tmpTexture->getStatesCache().WrapV = material.TextureLayer[i].TextureWrapV;
			}

			tmpTexture->getStatesCache().IsCached = true;
		}
	}


	// Get OpenGL ES2.0 texture wrap mode from Irrlicht wrap mode.
	GLint COpenGL3DriverBase::getTextureWrapMode(u8 clamp) const
	{
		switch (clamp)
		{
			case ETC_CLAMP:
			case ETC_CLAMP_TO_EDGE:
			case ETC_CLAMP_TO_BORDER:
				return GL_CLAMP_TO_EDGE;
			case ETC_MIRROR:
				return GL_REPEAT;
			default:
				return GL_REPEAT;
		}
	}


	//! sets the needed renderstates
	void COpenGL3DriverBase::setRenderStates2DMode(bool alpha, bool texture, bool alphaChannel)
	{
		if ( LockRenderStateMode )
			return;

		COpenGL3Renderer2D* nextActiveRenderer = texture ? MaterialRenderer2DTexture : MaterialRenderer2DNoTexture;

		if (CurrentRenderMode != ERM_2D)
		{
			// unset last 3d material
			if (CurrentRenderMode == ERM_3D)
			{
				if (static_cast<u32>(LastMaterial.MaterialType) < MaterialRenderers.size())
					MaterialRenderers[LastMaterial.MaterialType].Renderer->OnUnsetMaterial();
			}

			CurrentRenderMode = ERM_2D;
		}
		else if ( MaterialRenderer2DActive && MaterialRenderer2DActive != nextActiveRenderer)
		{
			MaterialRenderer2DActive->OnUnsetMaterial();
		}

		MaterialRenderer2DActive = nextActiveRenderer;

		MaterialRenderer2DActive->OnSetMaterial(Material, LastMaterial, true, 0);
		LastMaterial = Material;
		CacheHandler->correctCacheMaterial(LastMaterial);

		// no alphaChannel without texture
		alphaChannel &= texture;

		if (alphaChannel || alpha)
		{
			CacheHandler->setBlend(true);
			CacheHandler->setBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
			CacheHandler->setBlendEquation(GL_FUNC_ADD);
		}
		else
			CacheHandler->setBlend(false);

		Material.setTexture(0, const_cast<COpenGL3Texture*>(CacheHandler->getTextureCache().get(0)));
		setTransform(ETS_TEXTURE_0, core::IdentityMatrix);

		if (texture)
		{
			if (OverrideMaterial2DEnabled)
				setTextureRenderStates(OverrideMaterial2D, false);
			else
				setTextureRenderStates(InitMaterial2D, false);
		}

		MaterialRenderer2DActive->OnRender(this, video::EVT_STANDARD);
	}


	void COpenGL3DriverBase::chooseMaterial2D()
	{
		if (!OverrideMaterial2DEnabled)
			Material = InitMaterial2D;

		if (OverrideMaterial2DEnabled)
		{
			OverrideMaterial2D.Lighting=false;
			OverrideMaterial2D.ZWriteEnable=EZW_OFF;
			OverrideMaterial2D.ZBuffer=ECFN_DISABLED; // it will be ECFN_DISABLED after merge
			OverrideMaterial2D.Lighting=false;

			Material = OverrideMaterial2D;
		}
	}


	//! \return Returns the name of the video driver.
	const wchar_t* COpenGL3DriverBase::getName() const
	{
		return Name.c_str();
	}

	void COpenGL3DriverBase::setViewPort(const core::rect<s32>& area)
	{
		core::rect<s32> vp = area;
		core::rect<s32> rendert(0, 0, getCurrentRenderTargetSize().Width, getCurrentRenderTargetSize().Height);
		vp.clipAgainst(rendert);

		if (vp.getHeight() > 0 && vp.getWidth() > 0)
			CacheHandler->setViewport(vp.UpperLeftCorner.X, getCurrentRenderTargetSize().Height - vp.UpperLeftCorner.Y - vp.getHeight(), vp.getWidth(), vp.getHeight());

		ViewPort = vp;
	}


	void COpenGL3DriverBase::setViewPortRaw(u32 width, u32 height)
	{
		CacheHandler->setViewport(0, 0, width, height);
		ViewPort = core::recti(0, 0, width, height);
	}


	//! Draws a 3d line.
	void COpenGL3DriverBase::draw3DLine(const core::vector3df& start,
			const core::vector3df& end, SColor color)
	{
		setRenderStates3DMode();

		S3DVertex vertices[2];
		vertices[0] = S3DVertex(start.X, start.Y, start.Z, 0, 0, 1, color, 0, 0);
		vertices[1] = S3DVertex(end.X, end.Y, end.Z, 0, 0, 1, color, 0, 0);

		drawArrays(GL_LINES, vtPrimitive, vertices, 2);
	}


	//! Only used by the internal engine. Used to notify the driver that
	//! the window was resized.
	void COpenGL3DriverBase::OnResize(const core::dimension2d<u32>& size)
	{
		CNullDriver::OnResize(size);
		CacheHandler->setViewport(0, 0, size.Width, size.Height);
		Transformation3DChanged = true;
	}


	//! Returns type of video driver
	E_DRIVER_TYPE COpenGL3DriverBase::getDriverType() const
	{
		return EDT_OPENGL3;
	}


	//! returns color format
	ECOLOR_FORMAT COpenGL3DriverBase::getColorFormat() const
	{
		return ColorFormat;
	}


	//! Get a vertex shader constant index.
	s32 COpenGL3DriverBase::getVertexShaderConstantID(const c8* name)
	{
		return getPixelShaderConstantID(name);
	}

	//! Get a pixel shader constant index.
	s32 COpenGL3DriverBase::getPixelShaderConstantID(const c8* name)
	{
		os::Printer::log("Error: Please call services->getPixelShaderConstantID(), not VideoDriver->getPixelShaderConstantID().");
		return -1;
	}

	//! Sets a vertex shader constant.
	void COpenGL3DriverBase::setVertexShaderConstant(const f32* data, s32 startRegister, s32 constantAmount)
	{
		os::Printer::log("Error: Please call services->setVertexShaderConstant(), not VideoDriver->setPixelShaderConstant().");
	}

	//! Sets a pixel shader constant.
	void COpenGL3DriverBase::setPixelShaderConstant(const f32* data, s32 startRegister, s32 constantAmount)
	{
		os::Printer::log("Error: Please call services->setPixelShaderConstant(), not VideoDriver->setPixelShaderConstant().");
	}

	//! Sets a constant for the vertex shader based on an index.
	bool COpenGL3DriverBase::setVertexShaderConstant(s32 index, const f32* floats, int count)
	{
		os::Printer::log("Error: Please call services->setVertexShaderConstant(), not VideoDriver->setVertexShaderConstant().");
		return false;
	}

	//! Int interface for the above.
	bool COpenGL3DriverBase::setVertexShaderConstant(s32 index, const s32* ints, int count)
	{
		os::Printer::log("Error: Please call services->setVertexShaderConstant(), not VideoDriver->setVertexShaderConstant().");
		return false;
	}

	bool COpenGL3DriverBase::setVertexShaderConstant(s32 index, const u32* ints, int count)
	{
		os::Printer::log("Error: Please call services->setVertexShaderConstant(), not VideoDriver->setVertexShaderConstant().");
		return false;
	}

	//! Sets a constant for the pixel shader based on an index.
	bool COpenGL3DriverBase::setPixelShaderConstant(s32 index, const f32* floats, int count)
	{
		os::Printer::log("Error: Please call services->setPixelShaderConstant(), not VideoDriver->setPixelShaderConstant().");
		return false;
	}

	//! Int interface for the above.
	bool COpenGL3DriverBase::setPixelShaderConstant(s32 index, const s32* ints, int count)
	{
		os::Printer::log("Error: Please call services->setPixelShaderConstant(), not VideoDriver->setPixelShaderConstant().");
		return false;
	}

	bool COpenGL3DriverBase::setPixelShaderConstant(s32 index, const u32* ints, int count)
	{
		os::Printer::log("Error: Please call services->setPixelShaderConstant(), not VideoDriver->setPixelShaderConstant().");
		return false;
	}

	//! Adds a new material renderer to the VideoDriver, using pixel and/or
	//! vertex shaders to render geometry.
	s32 COpenGL3DriverBase::addShaderMaterial(const c8* vertexShaderProgram,
			const c8* pixelShaderProgram,
			IShaderConstantSetCallBack* callback,
			E_MATERIAL_TYPE baseMaterial, s32 userData)
	{
		os::Printer::log("No shader support.");
		return -1;
	}


	//! Adds a new material renderer to the VideoDriver, using GLSL to render geometry.
	s32 COpenGL3DriverBase::addHighLevelShaderMaterial(
			const c8* vertexShaderProgram,
			const c8* vertexShaderEntryPointName,
			E_VERTEX_SHADER_TYPE vsCompileTarget,
			const c8* pixelShaderProgram,
			const c8* pixelShaderEntryPointName,
			E_PIXEL_SHADER_TYPE psCompileTarget,
			const c8* geometryShaderProgram,
			const c8* geometryShaderEntryPointName,
			E_GEOMETRY_SHADER_TYPE gsCompileTarget,
			scene::E_PRIMITIVE_TYPE inType,
			scene::E_PRIMITIVE_TYPE outType,
			u32 verticesOut,
			IShaderConstantSetCallBack* callback,
			E_MATERIAL_TYPE baseMaterial,
			s32 userData)
	{
		s32 nr = -1;
		COpenGL3MaterialRenderer* r = new COpenGL3MaterialRenderer(
			this, nr, vertexShaderProgram,
			pixelShaderProgram,
			callback, baseMaterial, userData);

		r->drop();
		return nr;
	}

	//! Returns a pointer to the IVideoDriver interface. (Implementation for
	//! IMaterialRendererServices)
	IVideoDriver* COpenGL3DriverBase::getVideoDriver()
	{
		return this;
	}


	//! Returns pointer to the IGPUProgrammingServices interface.
	IGPUProgrammingServices* COpenGL3DriverBase::getGPUProgrammingServices()
	{
		return this;
	}

	ITexture* COpenGL3DriverBase::addRenderTargetTexture(const core::dimension2d<u32>& size,
		const io::path& name, const ECOLOR_FORMAT format)
	{
		//disable mip-mapping
		bool generateMipLevels = getTextureCreationFlag(ETCF_CREATE_MIP_MAPS);
		setTextureCreationFlag(ETCF_CREATE_MIP_MAPS, false);

		COpenGL3Texture* renderTargetTexture = new COpenGL3Texture(name, size, ETT_2D, format, this);
		addTexture(renderTargetTexture);
		renderTargetTexture->drop();

		//restore mip-mapping
		setTextureCreationFlag(ETCF_CREATE_MIP_MAPS, generateMipLevels);

		return renderTargetTexture;
	}

	ITexture* COpenGL3DriverBase::addRenderTargetTextureCubemap(const irr::u32 sideLen, const io::path& name, const ECOLOR_FORMAT format)
	{
		//disable mip-mapping
		bool generateMipLevels = getTextureCreationFlag(ETCF_CREATE_MIP_MAPS);
		setTextureCreationFlag(ETCF_CREATE_MIP_MAPS, false);

		bool supportForFBO = (Feature.ColorAttachment > 0);

		const core::dimension2d<u32> size(sideLen, sideLen);
		core::dimension2du destSize(size);

		if (!supportForFBO)
		{
			destSize = core::dimension2d<u32>(core::min_(size.Width, ScreenSize.Width), core::min_(size.Height, ScreenSize.Height));
			destSize = destSize.getOptimalSize((size == size.getOptimalSize()), false, false);
		}

		COpenGL3Texture* renderTargetTexture = new COpenGL3Texture(name, destSize, ETT_CUBEMAP, format, this);
		addTexture(renderTargetTexture);
		renderTargetTexture->drop();

		//restore mip-mapping
		setTextureCreationFlag(ETCF_CREATE_MIP_MAPS, generateMipLevels);

		return renderTargetTexture;
	}


	//! Returns the maximum amount of primitives
	u32 COpenGL3DriverBase::getMaximalPrimitiveCount() const
	{
		return 65535;
	}

	bool COpenGL3DriverBase::setRenderTargetEx(IRenderTarget* target, u16 clearFlag, SColor clearColor, f32 clearDepth, u8 clearStencil)
	{
		if (target && target->getDriverType() != getDriverType())
		{
			os::Printer::log("Fatal Error: Tried to set a render target not owned by OpenGL 3 driver.", ELL_ERROR);
			return false;
		}

		core::dimension2d<u32> destRenderTargetSize(0, 0);

		if (target)
		{
			COpenGL3RenderTarget* renderTarget = static_cast<COpenGL3RenderTarget*>(target);

			CacheHandler->setFBO(renderTarget->getBufferID());
			renderTarget->update();

			destRenderTargetSize = renderTarget->getSize();

			setViewPortRaw(destRenderTargetSize.Width, destRenderTargetSize.Height);
		}
		else
		{
			CacheHandler->setFBO(0);

			destRenderTargetSize = core::dimension2d<u32>(0, 0);

			setViewPortRaw(ScreenSize.Width, ScreenSize.Height);
		}

		if (CurrentRenderTargetSize != destRenderTargetSize)
		{
			CurrentRenderTargetSize = destRenderTargetSize;

			Transformation3DChanged = true;
		}

		CurrentRenderTarget = target;

		clearBuffers(clearFlag, clearColor, clearDepth, clearStencil);

		return true;
	}

	void COpenGL3DriverBase::clearBuffers(u16 flag, SColor color, f32 depth, u8 stencil)
	{
		GLbitfield mask = 0;
		u8 colorMask = 0;
		bool depthMask = false;

		CacheHandler->getColorMask(colorMask);
		CacheHandler->getDepthMask(depthMask);

		if (flag & ECBF_COLOR)
		{
			CacheHandler->setColorMask(ECP_ALL);

			const f32 inv = 1.0f / 255.0f;
			glClearColor(color.getRed() * inv, color.getGreen() * inv,
				color.getBlue() * inv, color.getAlpha() * inv);

			mask |= GL_COLOR_BUFFER_BIT;
		}

		if (flag & ECBF_DEPTH)
		{
			CacheHandler->setDepthMask(true);
			glClearDepthf(depth);
			mask |= GL_DEPTH_BUFFER_BIT;
		}

		if (flag & ECBF_STENCIL)
		{
			glClearStencil(stencil);
			mask |= GL_STENCIL_BUFFER_BIT;
		}

		if (mask)
			glClear(mask);

		CacheHandler->setColorMask(colorMask);
		CacheHandler->setDepthMask(depthMask);
	}


	//! Returns an image created from the last rendered frame.
	// We want to read the front buffer to get the latest render finished.
	// This is not possible under ogl-es, though, so one has to call this method
	// outside of the render loop only.
	IImage* COpenGL3DriverBase::createScreenShot(video::ECOLOR_FORMAT format, video::E_RENDER_TARGET target)
	{
		if (target==video::ERT_MULTI_RENDER_TEXTURES || target==video::ERT_RENDER_TEXTURE || target==video::ERT_STEREO_BOTH_BUFFERS)
			return 0;

		GLint internalformat = GL_RGBA;
		GLint type = GL_UNSIGNED_BYTE;
		{
//			glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT, &internalformat);
//			glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_TYPE, &type);
			// there's a format we don't support ATM
			if (GL_UNSIGNED_SHORT_4_4_4_4 == type)
			{
				internalformat = GL_RGBA;
				type = GL_UNSIGNED_BYTE;
			}
		}

		IImage* newImage = 0;
		if (GL_RGBA == internalformat)
		{
			if (GL_UNSIGNED_BYTE == type)
				newImage = new CImage(ECF_A8R8G8B8, ScreenSize);
			else
				newImage = new CImage(ECF_A1R5G5B5, ScreenSize);
		}
		else
		{
			if (GL_UNSIGNED_BYTE == type)
				newImage = new CImage(ECF_R8G8B8, ScreenSize);
			else
				newImage = new CImage(ECF_R5G6B5, ScreenSize);
		}

		if (!newImage)
			return 0;

		u8* pixels = static_cast<u8*>(newImage->getData());
		if (!pixels)
		{
			newImage->drop();
			return 0;
		}

		glReadPixels(0, 0, ScreenSize.Width, ScreenSize.Height, internalformat, type, pixels);
		testGLError(__LINE__);

		// opengl images are horizontally flipped, so we have to fix that here.
		const s32 pitch = newImage->getPitch();
		u8* p2 = pixels + (ScreenSize.Height - 1) * pitch;
		u8* tmpBuffer = new u8[pitch];
		for (u32 i = 0; i < ScreenSize.Height; i += 2)
		{
			memcpy(tmpBuffer, pixels, pitch);
			memcpy(pixels, p2, pitch);
			memcpy(p2, tmpBuffer, pitch);
			pixels += pitch;
			p2 -= pitch;
		}
		delete [] tmpBuffer;

		// also GL_RGBA doesn't match the internal encoding of the image (which is BGRA)
		if (GL_RGBA == internalformat && GL_UNSIGNED_BYTE == type)
		{
			pixels = static_cast<u8*>(newImage->getData());
			for (u32 i = 0; i < ScreenSize.Height; i++)
			{
				for (u32 j = 0; j < ScreenSize.Width; j++)
				{
					u32 c = *(u32*) (pixels + 4 * j);
					*(u32*) (pixels + 4 * j) = (c & 0xFF00FF00) |
						((c & 0x00FF0000) >> 16) | ((c & 0x000000FF) << 16);
				}
				pixels += pitch;
			}
		}

		if (testGLError(__LINE__))
		{
			newImage->drop();
			return 0;
		}
		testGLError(__LINE__);
		return newImage;
	}

	void COpenGL3DriverBase::removeTexture(ITexture* texture)
	{
		CacheHandler->getTextureCache().remove(texture);
		CNullDriver::removeTexture(texture);
	}

	//! Set/unset a clipping plane.
	bool COpenGL3DriverBase::setClipPlane(u32 index, const core::plane3df& plane, bool enable)
	{
		if (index >= UserClipPlane.size())
			UserClipPlane.push_back(SUserClipPlane());

		UserClipPlane[index].Plane = plane;
		UserClipPlane[index].Enabled = enable;
		return true;
	}

	//! Enable/disable a clipping plane.
	void COpenGL3DriverBase::enableClipPlane(u32 index, bool enable)
	{
		UserClipPlane[index].Enabled = enable;
	}

	//! Get the ClipPlane Count
	u32 COpenGL3DriverBase::getClipPlaneCount() const
	{
		return UserClipPlane.size();
	}

	const core::plane3df& COpenGL3DriverBase::getClipPlane(irr::u32 index) const
	{
		if (index < UserClipPlane.size())
			return UserClipPlane[index].Plane;
		else
		{
			_IRR_DEBUG_BREAK_IF(true)	// invalid index
			static const core::plane3df dummy;
			return dummy;
		}
	}

	core::dimension2du COpenGL3DriverBase::getMaxTextureSize() const
	{
		return core::dimension2du(MaxTextureSize, MaxTextureSize);
	}

	GLenum COpenGL3DriverBase::getGLBlend(E_BLEND_FACTOR factor) const
	{
		static GLenum const blendTable[] =
		{
			GL_ZERO,
			GL_ONE,
			GL_DST_COLOR,
			GL_ONE_MINUS_DST_COLOR,
			GL_SRC_COLOR,
			GL_ONE_MINUS_SRC_COLOR,
			GL_SRC_ALPHA,
			GL_ONE_MINUS_SRC_ALPHA,
			GL_DST_ALPHA,
			GL_ONE_MINUS_DST_ALPHA,
			GL_SRC_ALPHA_SATURATE
		};

		return blendTable[factor];
	}

	bool COpenGL3DriverBase::getColorFormatParameters(ECOLOR_FORMAT format, GLint& internalFormat, GLenum& pixelFormat,
		GLenum& pixelType, void(**converter)(const void*, s32, void*)) const
	{
		bool supported = false;
		pixelFormat = GL_RGBA;
		pixelType = GL_UNSIGNED_BYTE;
		*converter = 0;

		switch (format)
		{
		case ECF_A1R5G5B5:
			supported = true;
			pixelFormat = GL_RGBA;
			pixelType = GL_UNSIGNED_SHORT_5_5_5_1;
			*converter = CColorConverter::convert_A1R5G5B5toR5G5B5A1;
			break;
		case ECF_R5G6B5:
			supported = true;
			pixelFormat = GL_RGB;
			pixelType = GL_UNSIGNED_SHORT_5_6_5;
			break;
		case ECF_R8G8B8:
			supported = true;
			pixelFormat = GL_RGB;
			pixelType = GL_UNSIGNED_BYTE;
			break;
		case ECF_A8R8G8B8:
			supported = true;
			if (queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_IMG_texture_format_BGRA8888) ||
				queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_EXT_texture_format_BGRA8888) ||
				queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_APPLE_texture_format_BGRA8888))
			{
				pixelFormat = GL_BGRA;
			}
			else
			{
				pixelFormat = GL_RGBA;
				*converter = CColorConverter::convert_A8R8G8B8toA8B8G8R8;
			}
			pixelType = GL_UNSIGNED_BYTE;
			break;
#ifdef GL_EXT_texture_compression_s3tc
		case ECF_DXT1:
			supported = true;
			pixelFormat = GL_RGBA;
			pixelType = GL_COMPRESSED_RGBA_S3TC_DXT1_EXT;
			break;
		case ECF_DXT2:
		case ECF_DXT3:
			supported = true;
			pixelFormat = GL_RGBA;
			pixelType = GL_COMPRESSED_RGBA_S3TC_DXT3_EXT;
			break;
		case ECF_DXT4:
		case ECF_DXT5:
			supported = true;
			pixelFormat = GL_RGBA;
			pixelType = GL_COMPRESSED_RGBA_S3TC_DXT5_EXT;
			break;
#endif
#ifdef GL_OES_compressed_ETC1_RGB8_texture
		case ECF_ETC1:
			supported = true;
			pixelFormat = GL_RGB;
			pixelType = GL_ETC1_RGB8_OES;
			break;
#endif
#ifdef GL_ES_VERSION_3_0 // TO-DO - fix when extension name will be available
		case ECF_ETC2_RGB:
			supported = true;
			pixelFormat = GL_RGB;
			pixelType = GL_COMPRESSED_RGB8_ETC2;
			break;
#endif
#ifdef GL_ES_VERSION_3_0 // TO-DO - fix when extension name will be available
		case ECF_ETC2_ARGB:
			supported = true;
			pixelFormat = GL_RGBA;
			pixelType = GL_COMPRESSED_RGBA8_ETC2_EAC;
			break;
#endif
		case ECF_D16:
			supported = true;
			pixelFormat = GL_DEPTH_COMPONENT;
			pixelType = GL_UNSIGNED_SHORT;
			break;
		case ECF_D32:
#if defined(GL_OES_depth32)
			if (queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_OES_depth32))
			{
				supported = true;
				pixelFormat = GL_DEPTH_COMPONENT;
				pixelType = GL_UNSIGNED_INT;
			}
#endif
			break;
		case ECF_D24S8:
#ifdef GL_OES_packed_depth_stencil
			if (queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_OES_packed_depth_stencil))
			{
				supported = true;
				pixelFormat = GL_DEPTH_STENCIL_OES;
				pixelType = GL_UNSIGNED_INT_24_8_OES;
			}
#endif
			break;
		case ECF_R8:
#if defined(GL_EXT_texture_rg)
			if (queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_EXT_texture_rg))
			{
				supported = true;
				pixelFormat = GL_RED_EXT;
				pixelType = GL_UNSIGNED_BYTE;
			}
#endif
			break;
		case ECF_R8G8:
#if defined(GL_EXT_texture_rg)
			if (queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_EXT_texture_rg))
			{
				supported = true;
				pixelFormat = GL_RG_EXT;
				pixelType = GL_UNSIGNED_BYTE;
			}
#endif
			break;
		case ECF_R16:
			break;
		case ECF_R16G16:
			break;
		case ECF_R16F:
#if defined(GL_OES_texture_half_float) && defined(GL_EXT_texture_rg)
			if (queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_EXT_texture_rg)
				&& queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_OES_texture_half_float)
				)
			{
				supported = true;
				pixelFormat = GL_RED_EXT;
				pixelType = GL_HALF_FLOAT_OES ;
			}
#endif
			break;
		case ECF_G16R16F:
#if defined(GL_OES_texture_half_float) && defined(GL_EXT_texture_rg)
			if (queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_EXT_texture_rg)
				&& queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_OES_texture_half_float)
				)
			{
				supported = true;
				pixelFormat = GL_RG_EXT;
				pixelType = GL_HALF_FLOAT_OES ;
			}
#endif
			break;
		case ECF_A16B16G16R16F:
#if defined(GL_OES_texture_half_float)
			if (queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_OES_texture_half_float))
			{
				supported = true;
				pixelFormat = GL_RGBA;
				pixelType = GL_HALF_FLOAT_OES ;
			}
#endif
			break;
		case ECF_R32F:
#if defined(GL_OES_texture_float) && defined(GL_EXT_texture_rg)
			if (queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_EXT_texture_rg)
				&& queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_OES_texture_float)
				)
			{
				supported = true;
				pixelFormat = GL_RED_EXT;
				pixelType = GL_FLOAT;
			}
#endif
			break;
		case ECF_G32R32F:
#if defined(GL_OES_texture_float) && defined(GL_EXT_texture_rg)
			if (queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_EXT_texture_rg)
				&& queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_OES_texture_float)
				)
			{
				supported = true;
				pixelFormat = GL_RG_EXT;
				pixelType = GL_FLOAT;
			}
#endif
			break;
		case ECF_A32B32G32R32F:
#if defined(GL_OES_texture_float)
			if (queryGLESFeature(COGLESCoreExtensionHandler::IRR_GL_OES_texture_half_float))
			{
				supported = true;
				pixelFormat = GL_RGBA;
				pixelType = GL_FLOAT ;
			}
#endif
			break;
		default:
			break;
		}

		// ES 2.0 says internalFormat must match pixelFormat (chapter 3.7.1 in Spec).
		// Doesn't mention if "match" means "equal" or some other way of matching, but
		// some bug on Emscripten and browsing discussions by others lead me to believe
		// it means they have to be equal. Note that this was different in OpenGL.
		internalFormat = pixelFormat;

#ifdef _IRR_IOS_PLATFORM_
		if (internalFormat == GL_BGRA)
			internalFormat = GL_RGBA;
#endif

		return supported;
	}

	bool COpenGL3DriverBase::queryTextureFormat(ECOLOR_FORMAT format) const
	{
		GLint dummyInternalFormat;
		GLenum dummyPixelFormat;
		GLenum dummyPixelType;
		void (*dummyConverter)(const void*, s32, void*);
		return getColorFormatParameters(format, dummyInternalFormat, dummyPixelFormat, dummyPixelType, &dummyConverter);
	}

	bool COpenGL3DriverBase::needsTransparentRenderPass(const irr::video::SMaterial& material) const
	{
		return CNullDriver::needsTransparentRenderPass(material) || material.isAlphaBlendOperation();
	}

	const SMaterial& COpenGL3DriverBase::getCurrentMaterial() const
	{
		return Material;
	}

	COpenGL3CacheHandler* COpenGL3DriverBase::getCacheHandler() const
	{
		return CacheHandler;
	}

} // end namespace
} // end namespace