renderer: implement not-clamped mapOverBright in GLSL

We cannot overBright separate stage as stage are clamped
within [0.0, 1.0] when blending multiple stages together,
meaning the result of the multiplication of a separate
light stage with a light factor will be clamped before
blending it with the color map.

This implementation implements overBright in the camera
shader, but to only apply this overBright to surfaces having
received lights, surfaces that do not receive lights gets
divided by the light factor in a way re-multiplying them
cancels the division.

Stages and surfaces to be blended over other stages or
surfaces are also divided to avoid multiplying multiple
time the same surface, in order to have the final result
being (m * a) + b instead of m * (a + b) wich would be
(m * a) + (m * b) and then sump up the factor, something
we don't want to do.

The legacy code for overbrighting (but clamping) the light at
BSP load is kept for when the feature is disabled, but rewritten
to make the code better.

Author: illwieckz

src/engine/renderer/gl_shader.cpp

@@ -1580,6 +1580,7 @@ GLShader_generic::GLShader_generic( GLShaderManager *manager ) :
 	u_ModelMatrix( this ),
 	u_ProjectionMatrixTranspose( this ),
 	u_ModelViewProjectionMatrix( this ),
+	u_LightFactor( this ),
 	u_ColorModulate( this ),
 	u_Color( this ),
 	u_Bones( this ),
@@ -1618,6 +1619,7 @@ GLShader_lightMapping::GLShader_lightMapping( GLShaderManager *manager ) :
 	u_ViewOrigin( this ),
 	u_ModelMatrix( this ),
 	u_ModelViewProjectionMatrix( this ),
+	u_LightFactor( this ),
 	u_Bones( this ),
 	u_VertexInterpolation( this ),
 	u_ReliefDepthScale( this ),
@@ -1938,6 +1940,7 @@ GLShader_skybox::GLShader_skybox( GLShaderManager *manager ) :
 	u_AlphaThreshold( this ),
 	u_ModelMatrix( this ),
 	u_ModelViewProjectionMatrix( this ),
+	u_LightFactor( this ),
 	u_VertexInterpolation( this ),
 	GLDeformStage( this ),
 	GLCompileMacro_USE_ALPHA_TESTING( this )
@@ -1954,6 +1957,7 @@ GLShader_fogQuake3::GLShader_fogQuake3( GLShaderManager *manager ) :
 	GLShader( "fogQuake3", ATTR_POSITION | ATTR_QTANGENT, manager ),
 	u_ModelMatrix( this ),
 	u_ModelViewProjectionMatrix( this ),
+	u_LightFactor( this ),
 	u_Color( this ),
 	u_Bones( this ),
 	u_VertexInterpolation( this ),
@@ -1982,6 +1986,7 @@ GLShader_fogGlobal::GLShader_fogGlobal( GLShaderManager *manager ) :
 	u_ViewMatrix( this ),
 	u_ModelViewProjectionMatrix( this ),
 	u_UnprojectMatrix( this ),
+	u_LightFactor( this ),
 	u_Color( this ),
 	u_FogDistanceVector( this ),
 	u_FogDepthVector( this )
@@ -2073,6 +2078,7 @@ 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

@@ -1304,6 +1304,21 @@ class GLCompileMacro_USE_ALPHA_TESTING :
 	}
 };
 
+class u_LightFactor :
+	GLUniform1f
+{
+public:
+	u_LightFactor( GLShader *shader ) :
+		GLUniform1f( shader, "u_LightFactor" )
+	{
+	}
+
+	void SetUniform_LightFactor( const float lightFactor )
+	{
+		this->SetValue( lightFactor );
+	}
+};
+
 class u_TextureMatrix :
 	GLUniformMatrix4f
 {
@@ -2270,6 +2285,7 @@ class GLShader_generic :
 	public u_ModelMatrix,
  	public u_ProjectionMatrixTranspose,
 	public u_ModelViewProjectionMatrix,
+	public u_LightFactor,
 	public u_ColorModulate,
 	public u_Color,
 	public u_Bones,
@@ -2300,6 +2316,7 @@ class GLShader_lightMapping :
 	public u_ViewOrigin,
 	public u_ModelMatrix,
 	public u_ModelViewProjectionMatrix,
+	public u_LightFactor,
 	public u_Bones,
 	public u_VertexInterpolation,
 	public u_ReliefDepthScale,
@@ -2502,6 +2519,7 @@ class GLShader_skybox :
 	public u_AlphaThreshold,
 	public u_ModelMatrix,
 	public u_ModelViewProjectionMatrix,
+	public u_LightFactor,
 	public u_VertexInterpolation,
 	public GLDeformStage,
 	public GLCompileMacro_USE_ALPHA_TESTING
@@ -2515,6 +2533,7 @@ class GLShader_fogQuake3 :
 	public GLShader,
 	public u_ModelMatrix,
 	public u_ModelViewProjectionMatrix,
+	public u_LightFactor,
 	public u_Color,
 	public u_Bones,
 	public u_VertexInterpolation,
@@ -2537,6 +2556,7 @@ class GLShader_fogGlobal :
 	public u_ViewMatrix,
 	public u_ModelViewProjectionMatrix,
 	public u_UnprojectMatrix,
+	public u_LightFactor,
 	public u_Color,
 	public u_FogDistanceVector,
 	public u_FogDepthVector
@@ -2607,6 +2627,7 @@ 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

@@ -24,6 +24,8 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
 uniform sampler2D u_CurrentMap;
 uniform sampler3D u_ColorMap;
+
+uniform float u_LightFactor;
 uniform vec4      u_ColorModulate;
 uniform float     u_InverseGamma;
 
@@ -36,9 +38,11 @@ void	main()
 	// calculate the screen texcoord in the 0.0 to 1.0 range
 	vec2 st = gl_FragCoord.st / r_FBufSize;
 
-	vec4 original = clamp(texture2D(u_CurrentMap, st), 0.0, 1.0);
+	vec4 color = clamp(texture2D(u_CurrentMap, st), 0.0, 1.0);
+
+	color.rgb *= u_LightFactor;
 
-	vec4 color = original;
+	color.rgb = clamp(color.rgb, 0, 1);
 
 	// apply color grading
 	vec3 colCoord = color.rgb * 15.0 / 16.0 + 0.5 / 16.0;

src/engine/renderer/glsl_source/fogGlobal_fp.glsl

@@ -24,6 +24,8 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
 uniform sampler2D	u_ColorMap; // fog texture
 uniform sampler2D	u_DepthMap;
+
+uniform float u_LightFactor;
 uniform vec3		u_ViewOrigin;
 uniform vec4		u_FogDistanceVector;
 uniform vec4		u_FogDepthVector;
@@ -52,5 +54,9 @@ void	main()
 	// st.s = vertexDistanceToCamera;
 	st.t = 1.0;
 
-	outputColor = u_Color * texture2D(u_ColorMap, st);
+	vec4 color = texture2D(u_ColorMap, st);
+
+	color.rgb /= u_LightFactor;
+
+	outputColor = u_Color * color;
 }

src/engine/renderer/glsl_source/fogQuake3_fp.glsl

@@ -24,6 +24,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
 uniform sampler2D	u_ColorMap;
 
+uniform float u_LightFactor;
 IN(smooth) vec3		var_Position;
 IN(smooth) vec2		var_TexCoords;
 IN(smooth) vec4		var_Color;
@@ -35,6 +36,9 @@ void	main()
 	vec4 color = texture2D(u_ColorMap, var_TexCoords);
 
 	color *= var_Color;
+
+	color.rgb /= u_LightFactor;
+
 	outputColor = color;
 
 #if 0

src/engine/renderer/glsl_source/generic_fp.glsl

@@ -25,6 +25,10 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 uniform sampler2D	u_ColorMap;
 uniform float		u_AlphaThreshold;
 
+#if !defined(GENERIC_2D)
+uniform float u_LightFactor;
+#endif
+
 IN(smooth) vec2		var_TexCoords;
 IN(smooth) vec4		var_Color;
 
@@ -54,6 +58,11 @@ void	main()
 #endif
 
 	color *= var_Color;
+
+#if !defined(GENERIC_2D) && !defined(USE_DEPTH_FADE)
+	color.rgb /= u_LightFactor;
+#endif
+
 	outputColor = color;
 
 #if defined(GENERIC_2D)

src/engine/renderer/glsl_source/lightMapping_fp.glsl

@@ -27,6 +27,7 @@ uniform sampler2D	u_MaterialMap;
 uniform sampler2D	u_GlowMap;
 
 uniform float		u_AlphaThreshold;
+uniform float u_LightFactor;
 uniform vec3		u_ViewOrigin;
 
 IN(smooth) vec3		var_Position;
@@ -177,6 +178,8 @@ void main()
 		color.rgb += texture2D(u_GlowMap, texCoords).rgb;
 	#endif
 
+	color.rgb /= u_LightFactor;
+
 	outputColor = color;
 
 	// Debugging.

src/engine/renderer/glsl_source/skybox_fp.glsl

@@ -25,6 +25,8 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 const float radiusWorld = 4096.0; // Value used by quake 3 skybox code
 
 uniform samplerCube	u_ColorMap;
+
+uniform float u_LightFactor;
 uniform sampler2D	u_CloudMap;
 
 uniform bool        u_UseCloudMap;
@@ -73,5 +75,7 @@ void	main()
 			}
 	#endif
 
+	color.rgb /= u_LightFactor;
+
 	outputColor = color;
 }

src/engine/renderer/tr_backend.cpp

@@ -2960,6 +2960,9 @@ void RB_RenderGlobalFog()
 
 	gl_fogGlobalShader->SetUniform_ViewOrigin( backEnd.viewParms.orientation.origin );  // world space
 
+	// u_LightFactor
+	gl_fogGlobalShader->SetUniform_LightFactor( tr.mapLightFactor );
+
 	{
 		fog_t *fog;
 
@@ -3281,6 +3284,9 @@ void RB_CameraPostFX()
 	// enable shader, set arrays
 	gl_cameraEffectsShader->BindProgram( 0 );
 
+	// u_LightFactor
+	gl_cameraEffectsShader->SetUniform_LightFactor( tr.mapLightFactor );
+
 	gl_cameraEffectsShader->SetUniform_ColorModulate( backEnd.viewParms.gradingWeights );
 	gl_cameraEffectsShader->SetUniform_ModelViewProjectionMatrix( glState.modelViewProjectionMatrix[ glState.stackIndex ] );