From c83f28431b4fb63510b43e1ea76696bbbc668926 Mon Sep 17 00:00:00 2001
From: sfan5 <sfan5@live.de>
Date: Tue, 20 Feb 2024 21:27:15 +0100
Subject: [PATCH] Add API to delete shader materials

---
 include/EMaterialTypes.h          |  5 +++++
 include/IGPUProgrammingServices.h |  9 ++++++++
 source/Irrlicht/CNullDriver.cpp   | 34 ++++++++++++++++++++++++++++---
 source/Irrlicht/CNullDriver.h     |  2 ++
 4 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/include/EMaterialTypes.h b/include/EMaterialTypes.h
index b313692..9055491 100644
--- a/include/EMaterialTypes.h
+++ b/include/EMaterialTypes.h
@@ -5,6 +5,8 @@
 #ifndef __E_MATERIAL_TYPES_H_INCLUDED__
 #define __E_MATERIAL_TYPES_H_INCLUDED__
 
+#include "irrTypes.h"
+
 namespace irr
 {
 namespace video
@@ -67,6 +69,9 @@ namespace video
 		0
 	};
 
+	constexpr u32 numBuiltInMaterials =
+		sizeof(sBuiltInMaterialTypeNames) / sizeof(char*) - 1;
+
 } // end namespace video
 } // end namespace irr
 
diff --git a/include/IGPUProgrammingServices.h b/include/IGPUProgrammingServices.h
index 885eee4..f172314 100644
--- a/include/IGPUProgrammingServices.h
+++ b/include/IGPUProgrammingServices.h
@@ -356,6 +356,15 @@ public:
 			scene::EPT_TRIANGLES, scene::EPT_TRIANGLE_STRIP, 0,
 			callback, baseMaterial, userData);
 	}
+
+	//! Delete a shader material and associated data.
+	/**
+	After you have deleted a material it is invalid to still use and doing
+	so might result in a crash. The ID may be reused in the future when new
+	materials are added.
+	\param material Number of the material type. Must not be a built-in
+	material. */
+	virtual void deleteShaderMaterial(s32 material) = 0;
 };
 
 
diff --git a/source/Irrlicht/CNullDriver.cpp b/source/Irrlicht/CNullDriver.cpp
index 0e7a426..b35e719 100644
--- a/source/Irrlicht/CNullDriver.cpp
+++ b/source/Irrlicht/CNullDriver.cpp
@@ -41,6 +41,14 @@ IImageWriter* createImageWriterJPG();
 //! creates a writer which is able to save png images
 IImageWriter* createImageWriterPNG();
 
+namespace {
+	//! no-op material renderer
+	class CDummyMaterialRenderer : public IMaterialRenderer {
+	public:
+		CDummyMaterialRenderer() {}
+	};
+}
+
 
 //! constructor
 CNullDriver::CNullDriver(io::IFileSystem* io, const core::dimension2d<u32>& screenSize)
@@ -1525,7 +1533,7 @@ s32 CNullDriver::addMaterialRenderer(IMaterialRenderer* renderer, const char* na
 	r.Renderer = renderer;
 	r.Name = name;
 
-	if (name == 0 && (MaterialRenderers.size() < (sizeof(sBuiltInMaterialTypeNames) / sizeof(char*))-1 ))
+	if (name == 0 && MaterialRenderers.size() < numBuiltInMaterials)
 	{
 		// set name of built in renderer so that we don't have to implement name
 		// setting in all available renderers.
@@ -1542,8 +1550,7 @@ s32 CNullDriver::addMaterialRenderer(IMaterialRenderer* renderer, const char* na
 //! Sets the name of a material renderer.
 void CNullDriver::setMaterialRendererName(u32 idx, const char* name)
 {
-	if (idx < (sizeof(sBuiltInMaterialTypeNames) / sizeof(char*))-1 ||
-		idx >= MaterialRenderers.size())
+	if (idx < numBuiltInMaterials || idx >= MaterialRenderers.size())
 		return;
 
 	MaterialRenderers[idx].Name = name;
@@ -1786,6 +1793,27 @@ s32 CNullDriver::addHighLevelShaderMaterialFromFiles(
 	return result;
 }
 
+void CNullDriver::deleteShaderMaterial(s32 material)
+{
+	const u32 idx = (u32)material;
+	if (idx < numBuiltInMaterials || idx >= MaterialRenderers.size())
+		return;
+
+	// if this is the last material we can drop it without consequence
+	if (idx == MaterialRenderers.size() - 1) {
+		if (MaterialRenderers[idx].Renderer)
+			MaterialRenderers[idx].Renderer->drop();
+		MaterialRenderers.erase(idx);
+		return;
+	}
+	// otherwise replace with a dummy renderer, we have to preserve the IDs
+	auto &ref = MaterialRenderers[idx];
+	if (ref.Renderer)
+		ref.Renderer->drop();
+	ref.Renderer = new CDummyMaterialRenderer();
+	ref.Name.clear();
+}
+
 
 //! Creates a render target texture.
 ITexture* CNullDriver::addRenderTargetTexture(const core::dimension2d<u32>& size,
diff --git a/source/Irrlicht/CNullDriver.h b/source/Irrlicht/CNullDriver.h
index e949372..77b9f7b 100644
--- a/source/Irrlicht/CNullDriver.h
+++ b/source/Irrlicht/CNullDriver.h
@@ -525,6 +525,8 @@ namespace video
 			E_MATERIAL_TYPE baseMaterial = video::EMT_SOLID,
 			s32 userData = 0) override;
 
+		virtual void deleteShaderMaterial(s32 material) override;
+
 		//! Returns a pointer to the mesh manipulator.
 		scene::IMeshManipulator* getMeshManipulator() override;