renderer: make possible to compress uncompressed textures

Add:

- r_compressColormaps
- r_compressSkyboxes

Author: illwieckz

src/engine/renderer/tr_backend.cpp

@@ -801,12 +801,10 @@ static GLint GL_ToSRGB( GLint internalFormat, bool isSRGB )
 				return GL_SRGB8;
 			case GL_RGBA8:
 				return GL_SRGB8_ALPHA8;
-#if 0 // Not used in the codebase.
 			case GL_COMPRESSED_RGB:
 			 	return GL_COMPRESSED_SRGB;
 			case GL_COMPRESSED_RGBA:
 				return GL_COMPRESSED_SRGB_ALPHA;
-#endif
 			case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
 				return GL_COMPRESSED_SRGB_S3TC_DXT1_EXT;
 			case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:

src/engine/renderer/tr_image.cpp

@@ -197,6 +197,7 @@ class ListImagesCmd : public Cmd::StaticCmd
 			 If internalformat is one of the six generic compressed internal formats, its value is replaced by the symbolic constant
 			 for a specific compressed internal format of the GL’s choosing with the same base internal format."
 			 Use 4x4 blocks with 8 bytes per block here as an estimate: */
+			{ GL_COMPRESSED_RGB, { "RGBC", 8 } },
 			{ GL_COMPRESSED_RGBA, { "RGBAC", 8 } },
 
 			/* https://registry.khronos.org/OpenGL/extensions/EXT/EXT_texture_compression_s3tc.txt
@@ -378,6 +379,7 @@ class ListImagesCmd : public Cmd::StaticCmd
 			{
 				switch ( image->internalFormat ) {
 					// Compressed formats encode blocks of 4x4 texels
+					case GL_COMPRESSED_RGB:
 					case GL_COMPRESSED_RGBA:
 					case GL_COMPRESSED_RED_RGTC1:
 					case GL_COMPRESSED_SIGNED_RED_RGTC1:
@@ -1203,6 +1205,22 @@ void R_UploadImage( const char *name, const byte **dataArray, int numLayers, int
 		Log::Warn( "An explicit format should be used instead of GL_RGBA for image %s", name );
 	}
 
+	if ( image->bits & IF_COMPRESS )
+	{
+		switch ( internalFormat )
+		{
+			case GL_RED:
+			case GL_RGB8:
+				internalFormat = GL_COMPRESSED_RGB;
+				break;
+			case GL_RGBA8:
+				internalFormat = GL_COMPRESSED_RGBA;
+				break;
+			default:
+				break;
+		}
+	}
+
 	Log::Debug( "Uploading image %s (%d×%d, %d layers, %0#x type, %0#x format)", name, scaledWidth, scaledHeight, numLayers, image->type, internalFormat );
 
 	// 3D textures are uploaded in slices via glTexSubImage3D,

src/engine/renderer/tr_local.h

@@ -510,7 +510,8 @@ enum class ssaoMode {
 	  IF_BC5 = BIT( 23 ),
 	  IF_RGBA32UI = BIT( 24 ),
 	  IF_HOMEPATH = BIT( 25 ),
-	  IF_NOALPHA = BIT( 26 )
+	  IF_NOALPHA = BIT( 26 ),
+	  IF_COMPRESS = BIT(27)
 	};
 
 	enum class filterType_t

src/engine/renderer/tr_shader.cpp

@@ -87,6 +87,11 @@ static Cvar::Cvar<float> r_portalDefaultRange(
 Cvar::Cvar<bool> r_depthShaders(
 	"r_depthShaders", "use depth pre-pass shaders", Cvar::CHEAT, true);
 
+Cvar::Cvar<bool> r_compressColormaps(
+	"r_compressColormaps", "compress uncompressed color maps", Cvar::NONE, false);
+Cvar::Cvar<bool> r_compressSkyboxes(
+	"r_compressSkyboxes", "compress uncompressed skyboxes", Cvar::NONE, false);
+
 struct delayedStageTexture_t {
 	bool active;
 	stageType_t type;
@@ -1518,6 +1523,25 @@ static bool LoadMap( shaderStage_t *stage, const char *buffer, stageType_t type,
 		}
 	}
 
+	if ( r_compressColormaps.Get() )
+	{
+		if ( ! ( shader.registerFlags & RSF_2D ) )
+		{
+			switch ( type )
+			{
+				case stageType_t::ST_COLORMAP:
+				case stageType_t::ST_DIFFUSEMAP:
+				case stageType_t::ST_GLOWMAP:
+				case stageType_t::ST_REFLECTIONMAP:
+				case stageType_t::ST_SKYBOXMAP:
+					imageParams.bits |= IF_COMPRESS;
+					break;
+				default:
+					break;
+			}
+		}
+	}
+
 	// determine image options
 	if ( stage->overrideNoPicMip || shader.noPicMip || stage->highQuality || stage->forceHighQuality )
 	{
@@ -3719,6 +3743,11 @@ static void ParseSkyParms( const char **text )
 			imageParams.bits |= IF_SRGB;
 		}
 
+		if ( r_compressSkyboxes.Get() )
+		{
+			imageParams.bits |= IF_COMPRESS;
+		}
+
 		shader.sky.outerbox = R_FindCubeImage( prefix, imageParams );
 
 		if ( !shader.sky.outerbox )
@@ -6410,6 +6439,12 @@ shader_t       *R_FindShader( const char *name, int flags )
 			imageParams.bits |= IF_SRGB;
 		}
 
+		// HACK: Detect color grade images with RSF_NOMIP.
+		if ( r_compressColormaps.Get() && ! ( flags & RSF_NOMIP ) )
+		{
+			imageParams.bits |= IF_COMPRESS;
+		}
+
 		image = R_FindImageFile( fileName, imageParams );
 	}
 
@@ -7034,6 +7069,8 @@ void R_InitShaders()
 	Cvar::Latch(r_dpMaterial);
 	Cvar::Latch(r_depthShaders);
 	Cvar::Latch(r_portalDefaultRange);
+	Cvar::Latch(r_compressColormaps);
+	Cvar::Latch(r_compressSkyboxes);
 
 	memset( shaderTableHashTable, 0, sizeof( shaderTableHashTable ) );
 	memset( shaderHashTable, 0, sizeof( shaderHashTable ) );