irrlicht/source/Irrlicht/COGLESCoreExtensionHandler.h

// Copyright (C) 2017 Michael Zeilfelder
// This file is part of the "Irrlicht Engine".
// For conditions of distribution and use, see copyright notice in Irrlicht.h

#pragma once

// Can be included from different ES versions
// (this is also the reason why this file is header-only as correct OGL ES headers have to be included first)

#include "irrMath.h"
#include "COpenGLCoreFeature.h"

namespace irr
{
namespace video
{

	class COGLESCoreExtensionHandler
	{
	public:
		// Enums used internally to check for ES extensions quickly.
		// We buffer all extensions on start once in an array.
		// All OpenGL ES versions share the same extensions (WebGL adds it's own extensions on top of ES2)
		enum EOGLESFeatures
		{
			// If you update this enum also update the corresponding OGLESFeatureStrings string-array
			IRR_GL_APPLE_texture_2D_limited_npot,
			IRR_GL_APPLE_texture_format_BGRA8888,
			IRR_GL_EXT_blend_minmax,
			IRR_GL_EXT_read_format_bgra,
			IRR_GL_EXT_texture_filter_anisotropic,
			IRR_GL_EXT_texture_format_BGRA8888,
			IRR_GL_EXT_texture_lod_bias,
			IRR_GL_EXT_texture_rg,
			IRR_GL_IMG_read_format,
			IRR_GL_IMG_texture_format_BGRA8888,
			IRR_GL_IMG_user_clip_plane,
			IRR_GL_OES_blend_func_separate,
			IRR_GL_OES_blend_subtract,
			IRR_GL_OES_depth_texture,
			IRR_GL_OES_depth24,
			IRR_GL_OES_depth32,
			IRR_GL_OES_element_index_uint,
			IRR_GL_OES_framebuffer_object,
			IRR_GL_OES_packed_depth_stencil,
			IRR_GL_OES_point_size_array,
			IRR_GL_OES_point_sprite,
			IRR_GL_OES_read_format,
			IRR_GL_OES_stencil_wrap,
			IRR_GL_OES_texture_float,
			IRR_GL_OES_texture_half_float,
			IRR_GL_OES_texture_mirrored_repeat,
			IRR_GL_OES_texture_npot,

			IRR_OGLES_Feature_Count
		};

		COGLESCoreExtensionHandler()
		:	Version(0), MaxAnisotropy(1), MaxIndices(0xffff),
			MaxTextureSize(1), MaxTextureLODBias(0.f), StencilBuffer(false)
		{
			for (u32 i = 0; i < IRR_OGLES_Feature_Count; ++i)
				FeatureAvailable[i] = false;

			DimAliasedLine[0] = 1.f;
			DimAliasedLine[1] = 1.f;
			DimAliasedPoint[0] = 1.f;
			DimAliasedPoint[1] = 1.f;
		}

		virtual ~COGLESCoreExtensionHandler() {}

		const COpenGLCoreFeature& getFeature() const
		{
			return Feature;
		}

		void dump() const
		{
			for (u32 i = 0; i < IRR_OGLES_Feature_Count; ++i)
				os::Printer::log(getFeatureString(i), FeatureAvailable[i] ? " true" : " false");
		}

		bool queryGLESFeature(EOGLESFeatures feature) const
		{
			return FeatureAvailable[feature];
		}

	protected:

		const char* getFeatureString(size_t index) const
		{
			// One for each EOGLESFeatures
			static const char* const OGLESFeatureStrings[IRR_OGLES_Feature_Count] =
			{
				"GL_APPLE_texture_2D_limited_npot",
				"GL_APPLE_texture_format_BGRA8888",
				"GL_EXT_blend_minmax",
				"GL_EXT_read_format_bgra",
				"GL_EXT_texture_filter_anisotropic",
				"GL_EXT_texture_format_BGRA8888",
				"GL_EXT_texture_lod_bias",
				"GL_EXT_texture_rg",
				"GL_IMG_read_format",
				"GL_IMG_texture_format_BGRA8888",
				"GL_IMG_user_clip_plane",
				"GL_OES_blend_func_separate",
				"GL_OES_blend_subtract",
				"GL_OES_depth_texture",
				"GL_OES_depth24",
				"GL_OES_depth32",
				"GL_OES_element_index_uint",
				"GL_OES_framebuffer_object",
				"GL_OES_packed_depth_stencil",
				"GL_OES_point_size_array",
				"GL_OES_point_sprite",
				"GL_OES_read_format",
				"GL_OES_stencil_wrap",
				"GL_OES_texture_float",
				"GL_OES_texture_half_float",
				"GL_OES_texture_mirrored_repeat",
				"GL_OES_texture_npot",
			};

			return OGLESFeatureStrings[index];
		}


		void getGLVersion()
		{
			Version = 0;
			s32 multiplier = 100;

			core::stringc version(glGetString(GL_VERSION));

			for (u32 i = 0; i < version.size(); ++i)
			{
				if (version[i] >= '0' && version[i] <= '9')
				{
					if (multiplier > 1)
					{
						Version += static_cast<u16>(core::floor32(atof(&(version[i]))) * multiplier);
						multiplier /= 10;
					}
					else
					{
						break;
					}
				}
			}
		}

		void getGLExtensions()
		{
			core::stringc extensions = glGetString(GL_EXTENSIONS);
			os::Printer::log(extensions.c_str());

			const u32 size = extensions.size() + 1;
			c8* str = new c8[size];
			strncpy(str, extensions.c_str(), extensions.size());
			str[extensions.size()] = ' ';
			c8* p = str;

			for (u32 i=0; i<size; ++i)
			{
				if (str[i] == ' ')
				{
					str[i] = 0;
					if (*p)
						for (size_t j=0; j<IRR_OGLES_Feature_Count; ++j)
						{
							if (!strcmp(getFeatureString(j), p))
							{
								FeatureAvailable[j] = true;
								break;
							}
						}

					p = p + strlen(p) + 1;
				}
			}

			delete[] str;
		}


		COpenGLCoreFeature Feature;

		u16 Version;
		u8 MaxAnisotropy;
		u32 MaxIndices;
		u32 MaxTextureSize;
		f32 MaxTextureLODBias;
		//! Minimal and maximal supported thickness for lines without smoothing
		float DimAliasedLine[2];
		//! Minimal and maximal supported thickness for points without smoothing
		float DimAliasedPoint[2];
		bool StencilBuffer;
		bool FeatureAvailable[IRR_OGLES_Feature_Count];
	};
}
}