Simplify full-range overbright implementation

Multiply lightmaps and light grid by the light factor right when they
are used, instead of the elaborate canceling system. Vertex light
multiplication in lightmapped stages is handled by the scaling of the
white image lightmap (treated as 4.0). Various bugs will be fixed, since
the canceling approach relied on detecting an enormous amount of special
cases and not all of them were handled.

In a few places there can be issues with intermediate color buffer values
exceeding 1.0, but this is worked around (on reasonably good hardware) by
the previous commit setting up an RGBA16F framebuffer. When limited to
RGBA8 framebuffers, as can be tried with r_highPrecisionRendering 0,
this rewrite is a mixed bag. In some places it leads to clamping in the
color buffer (example: Pulse viewpos 4822 -1312 -1314 98 13), while in
others it improves results due to the effective 2 extra bits of
precision in the framebuffer (example: Procyon viewpos -955 3443 276 94
7).

There are a few cases where lightmap/lightgrid scaling doesn't apply
that required special handling:
- For intermediate stages of light styles, the already-existing
  detection of STYLELIGHTMAP and STYLECOLORMAP is used. For these stage
  types u_Color is scaled by the light factor. Example: metro-b1-2
  viewpos -1172 627 107 94 -21.
- For non-lightmapped vertex-lit surfaces, u_ColorModulate is scaled
  by the light factor. Example: station15 small plants.
- For fullbright lightmapped stages, the light factor is set to 1.
  Example: Procyon star chart.

Some bugs (in non-clamped overbright mode) that are fixed by this commit:
- Non-lightmapped vertex-lit surfaces (like the station15 plants) are
  now scaled by the light factor as they should be.
- Procyon star chart is no longer too dark with material system.
- Glowmap-like stage implemented with q3 syntax in a control panel
  shader are no longer wrongly overbright-scaled, causing visual noise.
  zittrig-arena viewpos 1201 -301 -338 87 0

Co-authored-by: Thomas Debesse <dev@illwieckz.net>

Author: slipher

src/engine/renderer/Material.cpp

@@ -222,15 +222,12 @@ void UpdateSurfaceDataGeneric3D( uint32_t* materials, Material& material, drawSu
 	// u_AlphaThreshold
 	gl_genericShaderMaterial->SetUniform_AlphaTest( pStage->stateBits );
 
-	// u_InverseLightFactor
-	float inverseLightFactor = pStage->cancelOverBright ? tr.mapInverseLightFactor : 1.0f;
-	gl_genericShaderMaterial->SetUniform_InverseLightFactor( inverseLightFactor );
-
 	// u_ColorModulate
 	colorGen_t rgbGen = SetRgbGen( pStage );
 	alphaGen_t alphaGen = SetAlphaGen( pStage );
 
-	gl_genericShaderMaterial->SetUniform_ColorModulate( rgbGen, alphaGen );
+	bool mayUseVertexOverbright = pStage->type == stageType_t::ST_COLORMAP && drawSurf->bspSurface;
+	gl_genericShaderMaterial->SetUniform_ColorModulate( rgbGen, alphaGen, mayUseVertexOverbright );
 
 	Tess_ComputeColor( pStage );
 	gl_genericShaderMaterial->SetUniform_Color( tess.svars.color );
@@ -291,12 +288,9 @@ void UpdateSurfaceDataLightMapping( uint32_t* materials, Material& material, dra
 	bool enableGridLighting = ( lightMode == lightMode_t::GRID );
 	bool enableGridDeluxeMapping = ( deluxeMode == deluxeMode_t::GRID );
 
-	// u_InverseLightFactor
-	/* HACK: use sign to know if there is a light or not, and
-	then if it will receive overbright multiplication or not. */
-	bool cancelOverBright = pStage->cancelOverBright || lightMode == lightMode_t::FULLBRIGHT;
-	float inverseLightFactor = cancelOverBright ? tr.mapInverseLightFactor : -tr.mapInverseLightFactor;
-	gl_lightMappingShaderMaterial->SetUniform_InverseLightFactor( inverseLightFactor );
+	// u_LightFactor
+	gl_lightMappingShaderMaterial->SetUniform_LightFactor(
+		lightMode == lightMode_t::FULLBRIGHT ? 1.0f : tr.mapLightFactor );
 
 	// u_ColorModulate
 	gl_lightMappingShaderMaterial->SetUniform_ColorModulate( rgbGen, alphaGen );
@@ -470,9 +464,6 @@ void UpdateSurfaceDataSkybox( uint32_t* materials, Material& material, drawSurf_
 	// u_AlphaThreshold
 	gl_skyboxShaderMaterial->SetUniform_AlphaTest( GLS_ATEST_NONE );
 
-	// u_InverseLightFactor
-	gl_skyboxShaderMaterial->SetUniform_InverseLightFactor( tr.mapInverseLightFactor );
-
 	gl_skyboxShaderMaterial->WriteUniformsToBuffer( materials );
 }
 
@@ -620,9 +611,6 @@ void UpdateSurfaceDataFog( uint32_t* materials, Material& material, drawSurf_t*
 
 	const fog_t* fog = material.fog;
 
-	// u_InverseLightFactor
-	gl_fogQuake3ShaderMaterial->SetUniform_InverseLightFactor( tr.mapInverseLightFactor );
-
 	// u_Color
 	gl_fogQuake3ShaderMaterial->SetUniform_Color( fog->color );
 

src/engine/renderer/gl_shader.cpp

@@ -2210,7 +2210,6 @@ GLShader_generic::GLShader_generic( GLShaderManager *manager ) :
 	u_AlphaThreshold( this ),
 	u_ModelMatrix( this ),
 	u_ModelViewProjectionMatrix( this ),
-	u_InverseLightFactor( this ),
 	u_ColorModulate( this ),
 	u_Color( this ),
 	u_Bones( this ),
@@ -2243,7 +2242,6 @@ GLShader_genericMaterial::GLShader_genericMaterial( GLShaderManager* manager ) :
 	u_AlphaThreshold( this ),
 	u_ModelMatrix( this ),
 	u_ModelViewProjectionMatrix( this ),
-	u_InverseLightFactor( this ),
 	u_ColorModulate( this ),
 	u_Color( this ),
 	u_DepthScale( this ),
@@ -2285,7 +2283,7 @@ GLShader_lightMapping::GLShader_lightMapping( GLShaderManager *manager ) :
 	u_ViewOrigin( this ),
 	u_ModelMatrix( this ),
 	u_ModelViewProjectionMatrix( this ),
-	u_InverseLightFactor( this ),
+	u_LightFactor( this ),
 	u_Bones( this ),
 	u_VertexInterpolation( this ),
 	u_ReliefDepthScale( this ),
@@ -2354,7 +2352,7 @@ GLShader_lightMappingMaterial::GLShader_lightMappingMaterial( GLShaderManager* m
 	u_ViewOrigin( this ),
 	u_ModelMatrix( this ),
 	u_ModelViewProjectionMatrix( this ),
-	u_InverseLightFactor( this ),
+	u_LightFactor( this ),
 	u_ReliefDepthScale( this ),
 	u_ReliefOffsetBias( this ),
 	u_NormalScale( this ),
@@ -2413,7 +2411,6 @@ GLShader_forwardLighting_omniXYZ::GLShader_forwardLighting_omniXYZ( GLShaderMana
 	u_ViewOrigin( this ),
 	u_LightOrigin( this ),
 	u_LightColor( this ),
-	u_InverseLightFactor( this ),
 	u_LightRadius( this ),
 	u_LightScale( this ),
 	u_LightAttenuationMatrix( this ),
@@ -2467,7 +2464,6 @@ GLShader_forwardLighting_projXYZ::GLShader_forwardLighting_projXYZ( GLShaderMana
 	u_ViewOrigin( this ),
 	u_LightOrigin( this ),
 	u_LightColor( this ),
-	u_InverseLightFactor( this ),
 	u_LightRadius( this ),
 	u_LightScale( this ),
 	u_LightAttenuationMatrix( this ),
@@ -2532,7 +2528,6 @@ GLShader_forwardLighting_directionalSun::GLShader_forwardLighting_directionalSun
 	u_ViewOrigin( this ),
 	u_LightDir( this ),
 	u_LightColor( this ),
-	u_InverseLightFactor( this ),
 	u_LightRadius( this ),
 	u_LightScale( this ),
 	u_LightAttenuationMatrix( this ),
@@ -2622,7 +2617,6 @@ GLShader_reflection::GLShader_reflection( GLShaderManager *manager ):
 	u_NormalScale( this ),
 	u_VertexInterpolation( this ),
 	u_CameraPosition( this ),
-	u_InverseLightFactor( this ),
 	GLDeformStage( this ),
 	GLCompileMacro_USE_VERTEX_SKINNING( this ),
 	GLCompileMacro_USE_VERTEX_ANIMATION( this ),
@@ -2651,7 +2645,6 @@ GLShader_reflectionMaterial::GLShader_reflectionMaterial( GLShaderManager* manag
 	u_ReliefOffsetBias( this ),
 	u_NormalScale( this ),
 	u_CameraPosition( this ),
-	u_InverseLightFactor( this ),
 	GLDeformStage( this ),
 	GLCompileMacro_USE_HEIGHTMAP_IN_NORMALMAP( this ),
 	GLCompileMacro_USE_RELIEF_MAPPING( this ) {
@@ -2673,8 +2666,7 @@ GLShader_skybox::GLShader_skybox( GLShaderManager *manager ) :
 	u_UseCloudMap( this ),
 	u_AlphaThreshold( this ),
 	u_ModelMatrix( this ),
-	u_ModelViewProjectionMatrix( this ),
-	u_InverseLightFactor( this )
+	u_ModelViewProjectionMatrix( this )
 {
 }
 
@@ -2694,9 +2686,8 @@ GLShader_skyboxMaterial::GLShader_skyboxMaterial( GLShaderManager* manager ) :
 	u_UseCloudMap( this ),
 	u_AlphaThreshold( this ),
 	u_ModelMatrix( this ),
-	u_ModelViewProjectionMatrix( this ),
-	u_InverseLightFactor( this ) {
-}
+	u_ModelViewProjectionMatrix( this )
+{}
 
 void GLShader_skyboxMaterial::SetShaderProgramUniforms( shaderProgram_t* shaderProgram ) {
 	glUniform1i( glGetUniformLocation( shaderProgram->program, "u_ColorMap" ), 0 );
@@ -2708,7 +2699,6 @@ GLShader_fogQuake3::GLShader_fogQuake3( GLShaderManager *manager ) :
 	u_FogMap( this ),
 	u_ModelMatrix( this ),
 	u_ModelViewProjectionMatrix( this ),
-	u_InverseLightFactor( this ),
 	u_Color( this ),
 	u_Bones( this ),
 	u_VertexInterpolation( this ),
@@ -2731,7 +2721,6 @@ GLShader_fogQuake3Material::GLShader_fogQuake3Material( GLShaderManager* manager
 	u_FogMap( this ),
 	u_ModelMatrix( this ),
 	u_ModelViewProjectionMatrix( this ),
-	u_InverseLightFactor( this ),
 	u_Color( this ),
 	u_FogDistanceVector( this ),
 	u_FogDepthVector( this ),
@@ -2751,7 +2740,6 @@ GLShader_fogGlobal::GLShader_fogGlobal( GLShaderManager *manager ) :
 	u_ViewMatrix( this ),
 	u_ModelViewProjectionMatrix( this ),
 	u_UnprojectMatrix( this ),
-	u_InverseLightFactor( this ),
 	u_Color( this ),
 	u_FogDistanceVector( this ),
 	u_FogDepthVector( this )
@@ -2861,8 +2849,7 @@ void GLShader_portal::SetShaderProgramUniforms( shaderProgram_t *shaderProgram )
 GLShader_contrast::GLShader_contrast( GLShaderManager *manager ) :
 	GLShader( "contrast", ATTR_POSITION, manager ),
 	u_ColorMap( this ),
-	u_ModelViewProjectionMatrix( this ),
-	u_InverseLightFactor( this )
+	u_ModelViewProjectionMatrix( this )
 {
 }
 
@@ -2878,7 +2865,6 @@ GLShader_cameraEffects::GLShader_cameraEffects( GLShaderManager *manager ) :
 	u_ColorModulate( this ),
 	u_TextureMatrix( this ),
 	u_ModelViewProjectionMatrix( this ),
-	u_LightFactor( this ),
 	u_DeformMagnitude( this ),
 	u_InverseGamma( this )
 {

src/engine/renderer/gl_shader.h

@@ -2150,21 +2150,6 @@ class u_LightFactor :
 	}
 };
 
-class u_InverseLightFactor :
-	GLUniform1f
-{
-public:
-	u_InverseLightFactor( GLShader *shader ) :
-		GLUniform1f( shader, "u_InverseLightFactor" )
-	{
-	}
-
-	void SetUniform_InverseLightFactor( const float inverseLightFactor )
-	{
-		this->SetValue( inverseLightFactor );
-	}
-};
-
 class u_ColorMap :
 	GLUniformSampler2D {
 	public:
@@ -3617,7 +3602,7 @@ class u_ColorModulate :
 	{
 		this->SetValue( v );
 	}
-	void SetUniform_ColorModulate( colorGen_t colorGen, alphaGen_t alphaGen )
+	void SetUniform_ColorModulate( colorGen_t colorGen, alphaGen_t alphaGen, bool vertexOverbright = false )
 	{
 		vec4_t v;
 		bool needAttrib = false;
@@ -3631,7 +3616,16 @@ class u_ColorModulate :
 		{
 			case colorGen_t::CGEN_VERTEX:
 				needAttrib = true;
-				VectorSet( v, 1, 1, 1 );
+				if ( vertexOverbright )
+				{
+					// vertexOverbright is only needed for non-lightmapped cases. When there is a
+					// lightmap, this is done by multiplying with the overbright-scaled white image
+					VectorSet( v, tr.mapLightFactor, tr.mapLightFactor, tr.mapLightFactor );
+				}
+				else
+				{
+					VectorSet( v, 1, 1, 1 );
+				}
 				break;
 
 			case colorGen_t::CGEN_ONE_MINUS_VERTEX:
@@ -3946,7 +3940,6 @@ class GLShader_generic :
 	public u_AlphaThreshold,
 	public u_ModelMatrix,
 	public u_ModelViewProjectionMatrix,
-	public u_InverseLightFactor,
 	public u_ColorModulate,
 	public u_Color,
 	public u_Bones,
@@ -3976,7 +3969,6 @@ class GLShader_genericMaterial :
 	public u_AlphaThreshold,
 	public u_ModelMatrix,
 	public u_ModelViewProjectionMatrix,
-	public u_InverseLightFactor,
 	public u_ColorModulate,
 	public u_Color,
 	public u_DepthScale,
@@ -4015,7 +4007,7 @@ class GLShader_lightMapping :
 	public u_ViewOrigin,
 	public u_ModelMatrix,
 	public u_ModelViewProjectionMatrix,
-	public u_InverseLightFactor,
+	public u_LightFactor,
 	public u_Bones,
 	public u_VertexInterpolation,
 	public u_ReliefDepthScale,
@@ -4067,7 +4059,7 @@ class GLShader_lightMappingMaterial :
 	public u_ViewOrigin,
 	public u_ModelMatrix,
 	public u_ModelViewProjectionMatrix,
-	public u_InverseLightFactor,
+	public u_LightFactor,
 	public u_ReliefDepthScale,
 	public u_ReliefOffsetBias,
 	public u_NormalScale,
@@ -4113,7 +4105,6 @@ class GLShader_forwardLighting_omniXYZ :
 	public u_ViewOrigin,
 	public u_LightOrigin,
 	public u_LightColor,
-	public u_InverseLightFactor,
 	public u_LightRadius,
 	public u_LightScale,
 	public u_LightAttenuationMatrix,
@@ -4157,7 +4148,6 @@ class GLShader_forwardLighting_projXYZ :
 	public u_ViewOrigin,
 	public u_LightOrigin,
 	public u_LightColor,
-	public u_InverseLightFactor,
 	public u_LightRadius,
 	public u_LightScale,
 	public u_LightAttenuationMatrix,
@@ -4208,7 +4198,6 @@ class GLShader_forwardLighting_directionalSun :
 	public u_ViewOrigin,
 	public u_LightDir,
 	public u_LightColor,
-	public u_InverseLightFactor,
 	public u_LightRadius,
 	public u_LightScale,
 	public u_LightAttenuationMatrix,
@@ -4275,7 +4264,6 @@ class GLShader_reflection :
 	public u_NormalScale,
 	public u_VertexInterpolation,
 	public u_CameraPosition,
-	public u_InverseLightFactor,
 	public GLDeformStage,
 	public GLCompileMacro_USE_VERTEX_SKINNING,
 	public GLCompileMacro_USE_VERTEX_ANIMATION,
@@ -4300,7 +4288,6 @@ class GLShader_reflectionMaterial :
 	public u_ReliefOffsetBias,
 	public u_NormalScale,
 	public u_CameraPosition,
-	public u_InverseLightFactor,
 	public GLDeformStage,
 	public GLCompileMacro_USE_HEIGHTMAP_IN_NORMALMAP,
 	public GLCompileMacro_USE_RELIEF_MAPPING {
@@ -4319,8 +4306,7 @@ class GLShader_skybox :
 	public u_UseCloudMap,
 	public u_AlphaThreshold,
 	public u_ModelMatrix,
-	public u_ModelViewProjectionMatrix,
-	public u_InverseLightFactor
+	public u_ModelViewProjectionMatrix
 {
 public:
 	GLShader_skybox( GLShaderManager *manager );
@@ -4337,8 +4323,7 @@ class GLShader_skyboxMaterial :
 	public u_UseCloudMap,
 	public u_AlphaThreshold,
 	public u_ModelMatrix,
-	public u_ModelViewProjectionMatrix,
-	public u_InverseLightFactor {
+	public u_ModelViewProjectionMatrix {
 	public:
 	GLShader_skyboxMaterial( GLShaderManager* manager );
 	void SetShaderProgramUniforms( shaderProgram_t* shaderProgram ) override;
@@ -4349,7 +4334,6 @@ class GLShader_fogQuake3 :
 	public u_FogMap,
 	public u_ModelMatrix,
 	public u_ModelViewProjectionMatrix,
-	public u_InverseLightFactor,
 	public u_Color,
 	public u_Bones,
 	public u_VertexInterpolation,
@@ -4370,7 +4354,6 @@ class GLShader_fogQuake3Material :
 	public u_FogMap,
 	public u_ModelMatrix,
 	public u_ModelViewProjectionMatrix,
-	public u_InverseLightFactor,
 	public u_Color,
 	public u_FogDistanceVector,
 	public u_FogDepthVector,
@@ -4389,7 +4372,6 @@ class GLShader_fogGlobal :
 	public u_ViewMatrix,
 	public u_ModelViewProjectionMatrix,
 	public u_UnprojectMatrix,
-	public u_InverseLightFactor,
 	public u_Color,
 	public u_FogDistanceVector,
 	public u_FogDepthVector
@@ -4484,8 +4466,7 @@ class GLShader_portal :
 class GLShader_contrast :
 	public GLShader,
 	public u_ColorMap,
-	public u_ModelViewProjectionMatrix,
-	public u_InverseLightFactor
+	public u_ModelViewProjectionMatrix
 {
 public:
 	GLShader_contrast( GLShaderManager *manager );
@@ -4499,7 +4480,6 @@ class GLShader_cameraEffects :
 	public u_ColorModulate,
 	public u_TextureMatrix,
 	public u_ModelViewProjectionMatrix,
-	public u_LightFactor,
 	public u_DeformMagnitude,
 	public u_InverseGamma
 {

src/engine/renderer/glsl_source/cameraEffects_fp.glsl

@@ -28,8 +28,6 @@ uniform sampler2D u_CurrentMap;
 uniform sampler3D u_ColorMap3D;
 #endif
 
-uniform float u_LightFactor;
-
 uniform vec4      u_ColorModulate;
 uniform float     u_InverseGamma;
 
@@ -44,8 +42,6 @@ void	main()
 
 	vec4 color = texture2D(u_CurrentMap, st);
 
-	color.rgb *= u_LightFactor;
-
 	color = clamp(color, 0.0, 1.0);
 
 #if defined(r_colorGrading)