Implement partial overbright clamping like q3

Author: slipher

src/engine/renderer/tr_bsp.cpp

@@ -74,10 +74,7 @@ static void R_ColorShiftLightingBytes( byte bytes[ 4 ] )
 	backward compatible with this bug for diagnostic purpose and fair comparison with
 	other buggy engines. */
 
-	if ( tr.mapOverBrightBits == 0 )
-	{
-		return;
-	}
+	ASSERT_LT( tr.overbrightBits, tr.mapOverBrightBits );
 
 	/* Shift the color data based on overbright range.
 
@@ -94,7 +91,7 @@ static void R_ColorShiftLightingBytes( byte bytes[ 4 ] )
 	what hardware overbright bit feature was not doing, but
 	this implementation is entirely software. */
 
-	int shift = tr.mapOverBrightBits;
+	int shift = tr.mapOverBrightBits - tr.overbrightBits;
 
 	// shift the data based on overbright range
 	int r = bytes[ 0 ] << shift;
@@ -120,10 +117,7 @@ static void R_ColorShiftLightingBytes( byte bytes[ 4 ] )
 
 static void R_ColorShiftLightingBytesCompressed( byte bytes[ 8 ] )
 {
-	if ( tr.mapOverBrightBits == 0 )
-	{
-		return;
-	}
+	ASSERT_LT( tr.overbrightBits, tr.mapOverBrightBits );
 
 	// color shift the endpoint colors in the dxt block
 	unsigned short rgb565 = bytes[1] << 8 | bytes[0];
@@ -164,7 +158,7 @@ R_ProcessLightmap
 */
 void R_ProcessLightmap( byte *bytes, int width, int height, int bits )
 {
-	if ( tr.mapOverBrightBits == 0 )
+	if ( tr.overbrightBits >= tr.mapOverBrightBits )
 	{
 		return;
 	}
@@ -668,7 +662,7 @@ static void R_LoadLightmaps( lump_t *l, const char *bspName )
 					lightMapBuffer[( index * 4 ) + 2 ] = buf_p[( ( x + ( y * internalLightMapSize ) ) * 3 ) + 2 ];
 					lightMapBuffer[( index * 4 ) + 3 ] = 255;
 
-					if ( tr.legacyOverBrightClamping )
+					if ( tr.overbrightBits < tr.mapOverBrightBits )
 					{
 						R_ColorShiftLightingBytes( &lightMapBuffer[( index * 4 ) + 0 ] );
 					}
@@ -1029,7 +1023,7 @@ static void ParseFace( dsurface_t *ds, drawVert_t *verts, bspSurface_t *surf, in
 		cv->verts[ i ].lightColor = Color::Adapt( verts[ i ].color );
 
 
-		if ( tr.legacyOverBrightClamping )
+		if ( tr.overbrightBits < tr.mapOverBrightBits )
 		{
 			R_ColorShiftLightingBytes( cv->verts[ i ].lightColor.ToArray() );
 		}
@@ -1239,7 +1233,7 @@ static void ParseMesh( dsurface_t *ds, drawVert_t *verts, bspSurface_t *surf )
 
 		points[ i ].lightColor = Color::Adapt( verts[ i ].color );
 
-		if ( tr.legacyOverBrightClamping )
+		if ( tr.overbrightBits < tr.mapOverBrightBits )
 		{
 			R_ColorShiftLightingBytes( points[ i ].lightColor.ToArray() );
 		}
@@ -1366,7 +1360,7 @@ static void ParseTriSurf( dsurface_t *ds, drawVert_t *verts, bspSurface_t *surf,
 
 			cv->verts[ i ].lightColor = Color::Adapt( verts[ i ].color );
 
-		if ( tr.legacyOverBrightClamping )
+		if ( tr.overbrightBits < tr.mapOverBrightBits )
 		{
 			R_ColorShiftLightingBytes( cv->verts[ i ].lightColor.ToArray() );
 		}
@@ -4145,7 +4139,7 @@ void R_LoadLightGrid( lump_t *l )
 			VectorSet( tmpAmbient, r_forceAmbient.Get(), r_forceAmbient.Get(), r_forceAmbient.Get() );
 		}
 
-		if ( tr.legacyOverBrightClamping )
+		if ( tr.overbrightBits < tr.mapOverBrightBits )
 		{
 			R_ColorShiftLightingBytes( tmpAmbient );
 			R_ColorShiftLightingBytes( tmpDirected );
@@ -4393,24 +4387,6 @@ void R_LoadEntities( lump_t *l, std::string &externalEntities )
 				tr.mapOverBrightBits = Math::Clamp( atof( value ), 0.0, 3.0 );
 				continue;
 			}
-
-			if ( !Q_stricmp( keyname, "overbrightClamping" ) )
-			{
-				if ( !Q_stricmp( value, "0" ) )
-				{
-					tr.legacyOverBrightClamping = false;
-				}
-				else if ( !Q_stricmp( value, "1" ) )
-				{
-					tr.legacyOverBrightClamping = true;
-				}
-				else
-				{
-					Log::Warn( "invalid value for worldspawn key overbrightClamping" );
-				}
-
-				continue;
-			}
 		}
 
 		// check for deluxe mapping provided by NetRadiant's q3map2
@@ -5143,6 +5119,9 @@ void RE_LoadWorldMap( const char *name )
 	}
 	R_LoadEntities( &header->lumps[ LUMP_ENTITIES ], externalEntities );
 
+	// Now we can set this after checking a possible worldspawn value for mapOverbrightBits
+	tr.overbrightBits = std::min( tr.mapOverBrightBits, r_overbrightBits.Get() );
+
 	R_LoadShaders( &header->lumps[ LUMP_SHADERS ] );
 
 	R_LoadLightmaps( &header->lumps[ LUMP_LIGHTMAPS ], name );
@@ -5180,7 +5159,6 @@ void RE_LoadWorldMap( const char *name )
 	tr.worldLight = tr.lightMode;
 	tr.modelLight = lightMode_t::FULLBRIGHT;
 	tr.modelDeluxe = deluxeMode_t::NONE;
-	tr.mapLightFactor = 1.0f;
 
 	// Use fullbright lighting for everything if the world is fullbright.
 	if ( tr.worldLight != lightMode_t::FULLBRIGHT )
@@ -5254,9 +5232,9 @@ void RE_LoadWorldMap( const char *name )
 
 	/* Set GLSL overbright parameters if the legacy clamped overbright isn't used
 	and the lighting mode is not fullbright. */
-	if ( !tr.legacyOverBrightClamping && tr.lightMode != lightMode_t::FULLBRIGHT )
+	if ( tr.lightMode != lightMode_t::FULLBRIGHT )
 	{
-		tr.mapLightFactor = pow( 2, tr.mapOverBrightBits );
+		tr.mapLightFactor = float( 1 << tr.overbrightBits );
 	}
 
 	tr.worldLoaded = true;

src/engine/renderer/tr_image.cpp

@@ -1853,7 +1853,7 @@ image_t *R_FindImageFile( const char *imageName, imageParams_t &imageParams )
 		return nullptr;
 	}
 
-	if ( imageParams.bits & IF_LIGHTMAP && tr.legacyOverBrightClamping )
+	if ( imageParams.bits & IF_LIGHTMAP )
 	{
 		R_ProcessLightmap( *pic, width, height, imageParams.bits );
 	}
@@ -3054,6 +3054,7 @@ void R_InitImages()
 	tr.lightmaps.reserve( 128 );
 	tr.deluxemaps.reserve( 128 );
 
+	//TODO rewrite WoT with new info :)
 	/* These are the values expected by the rest of the renderer
 	(esp. tr_bsp), used for "gamma correction of the map".
 	Both were set to 0 if we had neither COMPAT_ET nor COMPAT_Q3,
@@ -3113,8 +3114,9 @@ void R_InitImages()
 	Because tr.overbrightBits is always 0, tr.identityLight is
 	always 1.0f. We can entirely remove it. */
 
+	// TODO is there any reason to set these before a map is loaded?
 	tr.mapOverBrightBits = r_overbrightDefaultExponent.Get();
-	tr.legacyOverBrightClamping = r_overbrightDefaultClamp.Get();
+	tr.overbrightBits = std::min(tr.mapOverBrightBits, r_overbrightBits.Get());
 
 	// create default texture and white texture
 	R_CreateBuiltinImages();

src/engine/renderer/tr_init.cpp

@@ -92,7 +92,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 	cvar_t      *r_realtimeLightingCastShadows;
 	cvar_t      *r_precomputedLighting;
 	Cvar::Cvar<int> r_overbrightDefaultExponent("r_overbrightDefaultExponent", "default map light color shift (multiply by 2^x)", Cvar::NONE, 2);
-	Cvar::Cvar<bool> r_overbrightDefaultClamp("r_overbrightDefaultClamp", "clamp lightmap colors to 1 (in absence of map worldspawn value)", Cvar::NONE, false);
+	Cvar::Range<Cvar::Cvar<int>> r_overbrightBits("r_overbrightBits", "clamp lightmap colors to 2^x", Cvar::NONE, 1, 0, 3);
 	Cvar::Cvar<bool> r_overbrightIgnoreMapSettings("r_overbrightIgnoreMapSettings", "force usage of r_overbrightDefaultClamp / r_overbrightDefaultExponent, ignoring worldspawn", Cvar::NONE, false);
 	Cvar::Range<Cvar::Cvar<int>> r_lightMode("r_lightMode", "lighting mode: 0: fullbright (cheat), 1: vertex light, 2: grid light (cheat), 3: light map", Cvar::NONE, Util::ordinal(lightMode_t::MAP), Util::ordinal(lightMode_t::FULLBRIGHT), Util::ordinal(lightMode_t::MAP));
 	Cvar::Cvar<bool> r_colorGrading( "r_colorGrading", "Use color grading", Cvar::NONE, true );
@@ -1168,7 +1168,7 @@ ScreenshotCmd screenshotPNGRegistration("screenshotPNG", ssFormat_t::SSF_PNG, "p
 		r_realtimeLightingCastShadows = Cvar_Get( "r_realtimeLightingCastShadows", "1", 0 );
 		r_precomputedLighting = Cvar_Get( "r_precomputedLighting", "1", CVAR_CHEAT | CVAR_LATCH );
 		Cvar::Latch( r_overbrightDefaultExponent );
-		Cvar::Latch( r_overbrightDefaultClamp );
+		Cvar::Latch( r_overbrightBits );
 		Cvar::Latch( r_overbrightIgnoreMapSettings );
 		Cvar::Latch( r_lightMode );
 		Cvar::Latch( r_colorGrading );

src/engine/renderer/tr_local.h

@@ -2825,12 +2825,14 @@ enum class shaderProfilerRenderSubGroupsMode {
 
 		viewParms_t    viewParms;
 
-		// r_overbrightDefaultExponent, but can be overridden by mapper using the worldspawn
+		// Brightness scaling: roughly speaking, a lightmap value of x will be interpreted as
+		// min(x * pow(2, mapOverBrightBits), pow(2, overbrightBits))
+		// (but when a component hits the max allowed value, others are scaled down to keep the "same color")
 		int mapOverBrightBits;
-		// pow(2, mapOverbrightBits)
+		// min(r_overbrightBits.Get(), mapOverBrightBits)
+		int overbrightBits;
+		// pow(2, overbrightBits)
 		float mapLightFactor;
-		// May have to be true on some legacy maps: clamp and normalize multiplied colors.
-		bool legacyOverBrightClamping;
 
 		orientationr_t orientation; // for current entity
 
@@ -2954,7 +2956,7 @@ enum class shaderProfilerRenderSubGroupsMode {
 	extern cvar_t *r_realtimeLightingCastShadows;
 	extern cvar_t *r_precomputedLighting;
 	extern Cvar::Cvar<int> r_overbrightDefaultExponent;
-	extern Cvar::Cvar<bool> r_overbrightDefaultClamp;
+	extern Cvar::Range<Cvar::Cvar<int>> r_overbrightBits;
 	extern Cvar::Cvar<bool> r_overbrightIgnoreMapSettings;
 	extern Cvar::Range<Cvar::Cvar<int>> r_lightMode;
 	extern Cvar::Cvar<bool> r_colorGrading;