renderer: implement luminance-based FXAA

Author: illwieckz

src/engine/renderer/gl_shader.cpp

@@ -795,6 +795,16 @@ static std::string GenEngineConstants() {
 		AddDefine( str, "r_colorGrading", 1 );
 	}
 
+	if ( r_showLuminance.Get() )
+	{
+		AddDefine( str, "r_showLuminance", 1 );
+	}
+
+	if ( r_FXAA.Get() )
+	{
+		AddDefine( str, "r_FXAA", 1 );
+	}
+
 	if ( r_highPrecisionRendering.Get() ) {
 		AddDefine( str, "r_highPrecisionRendering", 1 );
 	}
@@ -3066,4 +3076,4 @@ GlobalUBOProxy::GlobalUBOProxy() :
 	u_Tonemap( this ),
 	u_TonemapParms( this ),
 	u_Exposure( this ) {
-}
+}

src/engine/renderer/glsl_source/cameraEffects_fp.glsl

@@ -111,5 +111,23 @@ void main()
 
 	color.xyz = pow(color.xyz, vec3(u_InverseGamma));
 
+	#if defined(r_FXAA) || defined(r_showLuminance)
+	{
+		// That luminance vector comes from a comment in fxaa3_11_fp.glsl.
+		vec3 luminanceVector = vec3( 0.299, 0.587, 0.114 );
+
+		float luminance = dot( color.rgb, luminanceVector );
+
+		#if defined(r_showLuminance)
+			color.rgb = vec3( luminance );
+		#endif
+
+		#if defined(r_FXAA)
+			// Encode luminance in alpha channel.
+			color.a = luminance;
+		#endif
+	}
+	#endif
+
 	outputColor = color;
 }

src/engine/renderer/glsl_source/fxaa_fp.glsl

@@ -42,7 +42,7 @@ ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 
 #define FXAA_PC 1
 #define FXAA_QUALITY_PRESET 12
-#define FXAA_GREEN_AS_LUMA 1
+#define FXAA_GREEN_AS_LUMA 0
 
 #insert fxaa3_11_fp
 
@@ -56,7 +56,7 @@ out vec4 outputColor;
 
 void	main()
 {
-	outputColor = FxaaPixelShader(
+	vec4 color = FxaaPixelShader(
 		gl_FragCoord.xy / r_FBufSize, //pos
 		vec4(0.0), //not used
 		u_ColorMap, //tex
@@ -74,4 +74,6 @@ void	main()
 		0.0, //not used
 		vec4(0.0) //not used
 	);
+
+	outputColor = vec4( color.rgb, 1.0f );
 }

src/engine/renderer/tr_init.cpp

@@ -286,6 +286,8 @@ Cvar::Cvar<int> r_rendererAPI( "r_rendererAPI", "Renderer API: 0: OpenGL, 1: Vul
 	Cvar::Cvar<float> r_bloomBlur( "r_bloomBlur", "Bloom strength", Cvar::NONE, 0.2 );
 	Cvar::Cvar<int> r_bloomPasses( "r_bloomPasses", "Amount of bloom passes in each direction", Cvar::NONE, 2 );
 
+	Cvar::Cvar<bool> r_showLuminance( "r_showLuminance", "Show luminance", Cvar::CHEAT, false );
+
 	Cvar::Cvar<bool> r_FXAA( "r_FXAA", "Fast approximate anti-aliasing", Cvar::NONE, false );
 
 	Cvar::Range<Cvar::Cvar<int>> r_msaa( "r_msaa", "Amount of MSAA samples. 0 to disable", Cvar::NONE, 0, 0, 64 );
@@ -1210,6 +1212,8 @@ ScreenshotCmd screenshotPNGRegistration("screenshotPNG", ssFormat_t::SSF_PNG, "p
 		Cvar::Latch( r_bloom );
 		Cvar::Latch( r_ssao );
 
+		Cvar::Latch( r_showLuminance );
+
 		Cvar::Latch( r_FXAA );
 
 		Cvar::Latch( r_msaa );

src/engine/renderer/tr_local.h

@@ -2780,6 +2780,8 @@ enum
 	extern Cvar::Cvar<int> r_bloomPasses;
 	extern Cvar::Range<Cvar::Cvar<int>> r_ssao;
 
+	extern Cvar::Cvar<bool> r_showLuminance;
+
 	extern Cvar::Cvar<bool> r_FXAA;
 
 	extern Cvar::Range<Cvar::Cvar<int>> r_msaa;