Correct alpha compare:

- Take into account coverage flags. This is still not quite correct without proper coverage emulation. - Discard pixels with zero alpha if uCvgXAlpha flag is set. Resulted pixel coverage is function of pixel alpha multiplied by actual coverage in that mode, thus pixel with zero alpha has zero coverage and discarded. Fixed regression in BAR, issue #866
gonetz · Mar 12, 2016 · b7369e9 · b7369e9
1 parent 56f85e0
commit b7369e9
Showing 6 changed files with 50 additions and 29 deletions.
diff --git a/src/GLES2/GLSLCombiner_gles2.cpp b/src/GLES2/GLSLCombiner_gles2.cpp
@@ -145,7 +145,7 @@ void DestroyShaderCombiner() {
 
 ShaderCombiner::ShaderCombiner(Combiner & _color, Combiner & _alpha, const gDPCombine & _combine) : m_combine(_combine)
 {
-	char strCombiner[1024];
+	char strCombiner[2048];
 	m_nInputs = compileCombiner(_color, _alpha, strCombiner);
 
 	if (usesTexture()) {
@@ -179,6 +179,10 @@ ShaderCombiner::ShaderCombiner(Combiner & _color, Combiner & _alpha, const gDPCo
 	strFragmentShader.append("  vec_color = vec4(input_color, vShadeColor.a); \n");
 	strFragmentShader.append(strCombiner);
 
+	strFragmentShader.append(
+		"  if (uCvgXAlpha != 0 && alpha2 == 0.0) discard; \n"
+		);
+
 	if (!g_weakGLSL) {
 		strFragmentShader.append(
 			"  lowp int fogUsage = uFogUsage;			\n"
@@ -253,6 +257,8 @@ void ShaderCombiner::_locateUniforms() {
 	LocateUniform(uFogMode);
 	LocateUniform(uFogUsage);
 	LocateUniform(uAlphaCompareMode);
+	LocateUniform(uCvgXAlpha);
+	LocateUniform(uAlphaCvgSel);
 	LocateUniform(uEnableAlphaTest);
 	LocateUniform(uEnableDepth);
 	LocateUniform(uEnableDepthCompare)
@@ -482,28 +488,23 @@ void ShaderCombiner::updateDepthInfo(bool _bForce) {
 void ShaderCombiner::updateAlphaTestInfo(bool _bForce) {
 	if (gDP.otherMode.cycleType == G_CYC_FILL) {
 		m_uniforms.uEnableAlphaTest.set(0, _bForce);
-		m_uniforms.uAlphaTestValue.set(0.0f, _bForce);
 	} else if (gDP.otherMode.cycleType == G_CYC_COPY) {
 		if (gDP.otherMode.alphaCompare & G_AC_THRESHOLD) {
 			m_uniforms.uEnableAlphaTest.set(1, _bForce);
+			m_uniforms.uAlphaCvgSel.set(0, _bForce);
 			m_uniforms.uAlphaTestValue.set(0.5f, _bForce);
 		} else {
 			m_uniforms.uEnableAlphaTest.set(0, _bForce);
-			m_uniforms.uAlphaTestValue.set(0.0f, _bForce);
 		}
-	} else if (((gDP.otherMode.alphaCompare & G_AC_THRESHOLD) != 0) && (gDP.otherMode.alphaCvgSel == 0) && (gDP.otherMode.forceBlender == 0 || gDP.blendColor.a > 0))	{
+	} else if ((gDP.otherMode.alphaCompare & G_AC_THRESHOLD) != 0) {
 		m_uniforms.uEnableAlphaTest.set(1, _bForce);
-		m_uniforms.uAlphaTestValue.set(max(gDP.blendColor.a, 1.0f / 256.0f), _bForce);
-	} else if ((gDP.otherMode.alphaCompare == G_AC_DITHER) && (gDP.otherMode.alphaCvgSel == 0))	{
-		m_uniforms.uEnableAlphaTest.set(1, _bForce);
-		m_uniforms.uAlphaTestValue.set(0.0f, _bForce);
-	} else if (gDP.otherMode.cvgXAlpha != 0)	{
-		m_uniforms.uEnableAlphaTest.set(1, _bForce);
-		m_uniforms.uAlphaTestValue.set(0.125f, _bForce);
+		m_uniforms.uAlphaTestValue.set(gDP.blendColor.a, _bForce);
+		m_uniforms.uAlphaCvgSel.set(gDP.otherMode.alphaCvgSel, _bForce);
 	} else {
 		m_uniforms.uEnableAlphaTest.set(0, _bForce);
-		m_uniforms.uAlphaTestValue.set(0.0f, _bForce);
 	}
+
+	m_uniforms.uCvgXAlpha.set(gDP.otherMode.cvgXAlpha, _bForce);
 }
 
 void SetMonochromeCombiner() {

diff --git a/src/GLES2/Shaders_gles2.h b/src/GLES2/Shaders_gles2.h
@@ -166,6 +166,8 @@ SHADER_VERSION
 "uniform lowp ivec2 uFbFixedAlpha;\n"
 "uniform lowp int uSpecialBlendMode;\n"
 "uniform lowp int uEnableAlphaTest;	\n"
+"uniform lowp int uCvgXAlpha;	\n"
+"uniform lowp int uAlphaCvgSel;	\n"
 "uniform lowp float uAlphaTestValue;\n"
 "uniform mediump vec2 uDepthScale;	\n"
 "IN lowp vec4 vShadeColor;	\n"
@@ -202,6 +204,8 @@ SHADER_VERSION
 "uniform lowp int uFogUsage;	\n"
 "uniform lowp int uSpecialBlendMode;\n"
 "uniform lowp int uEnableAlphaTest;	\n"
+"uniform lowp int uCvgXAlpha;	\n"
+"uniform lowp int uAlphaCvgSel;	\n"
 "uniform lowp float uAlphaTestValue;\n"
 "uniform mediump vec2 uDepthScale;	\n"
 "IN lowp vec4 vShadeColor;	\n"

diff --git a/src/GLSLCombiner.h b/src/GLSLCombiner.h
@@ -96,7 +96,8 @@ class ShaderCombiner {
 			uEnableDepth, uEnableDepthCompare, uEnableDepthUpdate,
 			uDepthMode, uDepthSource, uRenderState, uSpecialBlendMode,
 			uMaxTile, uTextureDetail, uTexturePersp, uTextureFilterMode, uMSAASamples,
-			uAlphaCompareMode, uAlphaDitherMode, uColorDitherMode;
+			uAlphaCompareMode, uAlphaDitherMode, uColorDitherMode,
+			uCvgXAlpha, uAlphaCvgSel;
 
 		fUniform uFogAlpha, uMinLod, uDeltaZ, uAlphaTestValue, uMSAAScale;
 

diff --git a/src/OGL3X/GLSLCombiner_ogl3x.cpp b/src/OGL3X/GLSLCombiner_ogl3x.cpp
@@ -282,7 +282,7 @@ ShaderCombiner::ShaderCombiner() : m_bNeedUpdate(true)
 
 ShaderCombiner::ShaderCombiner(Combiner & _color, Combiner & _alpha, const gDPCombine & _combine) : m_combine(_combine), m_bNeedUpdate(true)
 {
-	char strCombiner[1024];
+	char strCombiner[2048];
 	m_nInputs = compileCombiner(_color, _alpha, strCombiner);
 
 	const bool bUseLod = usesLOD();
@@ -369,6 +369,10 @@ ShaderCombiner::ShaderCombiner(Combiner & _color, Combiner & _alpha, const gDPCo
 	strFragmentShader.append("  vec_color = vec4(input_color, vShadeColor.a); \n");
 	strFragmentShader.append(strCombiner);
 
+	strFragmentShader.append(
+		"  if (uCvgXAlpha != 0 && alpha2 == 0.0) discard; \n"
+		);
+
 	if (config.generalEmulation.enableNoise != 0) {
 		strFragmentShader.append(
 			"  if (uColorDitherMode == 2) colorNoiseDither(snoise(), color2);	\n"
@@ -484,6 +488,8 @@ void ShaderCombiner::_locateUniforms() {
 	LocateUniform(uAlphaCompareMode);
 	LocateUniform(uAlphaDitherMode);
 	LocateUniform(uColorDitherMode);
+	LocateUniform(uCvgXAlpha);
+	LocateUniform(uAlphaCvgSel);
 	LocateUniform(uEnableLod);
 	LocateUniform(uEnableAlphaTest);
 	LocateUniform(uEnableDepth);
@@ -749,28 +755,23 @@ void ShaderCombiner::updateDepthInfo(bool _bForce) {
 void ShaderCombiner::updateAlphaTestInfo(bool _bForce) {
 	if (gDP.otherMode.cycleType == G_CYC_FILL) {
 		m_uniforms.uEnableAlphaTest.set(0, _bForce);
-		m_uniforms.uAlphaTestValue.set(0.0f, _bForce);
 	} else if (gDP.otherMode.cycleType == G_CYC_COPY) {
 		if (gDP.otherMode.alphaCompare & G_AC_THRESHOLD) {
 			m_uniforms.uEnableAlphaTest.set(1, _bForce);
+			m_uniforms.uAlphaCvgSel.set(0, _bForce);
 			m_uniforms.uAlphaTestValue.set(0.5f, _bForce);
 		} else {
 			m_uniforms.uEnableAlphaTest.set(0, _bForce);
-			m_uniforms.uAlphaTestValue.set(0.0f, _bForce);
 		}
-	} else if (((gDP.otherMode.alphaCompare & G_AC_THRESHOLD) != 0) && (gDP.otherMode.alphaCvgSel == 0) && (gDP.otherMode.forceBlender == 0 || gDP.blendColor.a > 0))	{
+	} else if ((gDP.otherMode.alphaCompare & G_AC_THRESHOLD) != 0) {
 		m_uniforms.uEnableAlphaTest.set(1, _bForce);
-		m_uniforms.uAlphaTestValue.set(max(gDP.blendColor.a, 1.0f / 256.0f), _bForce);
-	} else if ((gDP.otherMode.alphaCompare == G_AC_DITHER) && (gDP.otherMode.alphaCvgSel == 0))	{
-		m_uniforms.uEnableAlphaTest.set(1, _bForce);
-		m_uniforms.uAlphaTestValue.set(0.0f, _bForce);
-	} else if (gDP.otherMode.cvgXAlpha != 0)	{
-		m_uniforms.uEnableAlphaTest.set(1, _bForce);
-		m_uniforms.uAlphaTestValue.set(0.125f, _bForce);
+		m_uniforms.uAlphaTestValue.set(gDP.blendColor.a, _bForce);
+		m_uniforms.uAlphaCvgSel.set(gDP.otherMode.alphaCvgSel, _bForce);
 	} else {
 		m_uniforms.uEnableAlphaTest.set(0, _bForce);
-		m_uniforms.uAlphaTestValue.set(0.0f, _bForce);
 	}
+
+	m_uniforms.uCvgXAlpha.set(gDP.otherMode.cvgXAlpha, _bForce);
 }
 
 std::ostream & operator<< (std::ostream & _os, const ShaderCombiner & _combiner)

diff --git a/src/OGL3X/Shaders_ogl3x.h b/src/OGL3X/Shaders_ogl3x.h
@@ -168,6 +168,8 @@ MAIN_SHADER_VERSION
 "uniform lowp ivec2 uFbFixedAlpha;\n"
 "uniform lowp int uSpecialBlendMode;\n"
 "uniform lowp int uEnableAlphaTest;	\n"
+"uniform lowp int uCvgXAlpha;	\n"
+"uniform lowp int uAlphaCvgSel;	\n"
 "uniform lowp float uAlphaTestValue;\n"
 "uniform mediump vec2 uDepthScale;	\n"
 "in lowp vec4 vShadeColor;	\n"
@@ -215,6 +217,8 @@ MAIN_SHADER_VERSION
 "uniform lowp int uFogUsage;	\n"
 "uniform lowp int uSpecialBlendMode;\n"
 "uniform lowp int uEnableAlphaTest;	\n"
+"uniform lowp int uCvgXAlpha;	\n"
+"uniform lowp int uAlphaCvgSel;	\n"
 "uniform lowp float uAlphaTestValue;\n"
 "uniform mediump vec2 uDepthScale;	\n"
 "in lowp vec4 vShadeColor;	\n"

diff --git a/src/ShaderUtils.cpp b/src/ShaderUtils.cpp
@@ -253,12 +253,22 @@ int compileCombiner(Combiner & _color, Combiner & _alpha, char * _strShader)
 	}
 	strcpy(_strShader, "  alpha1 = ");
 	int nInputs = _compileCombiner(_alpha.stage[0], AlphaInput, _strShader);
+
 	strcat(_strShader,
-		"  if (uEnableAlphaTest != 0) {				\n"
-		"    lowp float alphaTestValue = (uAlphaCompareMode == 3 && alpha1 > 0.0) ? snoise() : uAlphaTestValue;	\n"
-		"    if  (alpha1 < alphaTestValue) discard;	\n"
-		"  }										\n"
+		"  if (uEnableAlphaTest != 0) {							\n"
+		"    lowp float alphaTestValue = (uAlphaCompareMode == 3) ? snoise() : uAlphaTestValue;	\n"
+		"    lowp float alphaValue = alpha1;					\n"
+		"    if  (uAlphaCvgSel == 0) {							\n"
+		"       alphaValue += 0.0078125;						\n"
+		"       alphaValue = clamp(alphaValue, 0.0, 1.0);		\n"
+		"    } else {											\n"
+		"       if (uCvgXAlpha != 0) alphaValue *= 0.5;			\n"
+		"       else alphaValue = 0.125;						\n"
+		"    }													\n"
+		"    if (alphaValue < alphaTestValue) discard;			\n"
+		"  }													\n"
 		);
+
 	strcat(_strShader, "  color1 = ");
 	nInputs |= _compileCombiner(_color.stage[0], ColorInput, _strShader);
 	strcat(_strShader, fragment_shader_blender);