Always apply the fragment shader if it is present

src/Pipeline/PixelRoutine.cpp

@@ -181,13 +181,14 @@ namespace sw
 
 			Bool alphaPass = true;
 
-			if(colorUsed())
-			{
 			#if PERF_PROFILE
 				Long shaderTime = Ticks();
 			#endif
 
+			if (spirvShader)
+			{
 				applyShader(cMask);
+			}
 
 			#if PERF_PROFILE
 				cycles[PERF_SHADER] += Ticks() - shaderTime;
@@ -203,7 +204,6 @@ namespace sw
 					sMask[q] &= cMask[q];
 				}
 			}
-			}
 
 			If(alphaPass)
 			{
@@ -234,15 +234,12 @@ namespace sw
 						}
 					}
 
-					if(colorUsed())
-					{
 					#if PERF_PROFILE
 						AddAtomic(Pointer<Long>(&profiler.ropOperations), 4);
 					#endif
 
 					rasterOperation(cBuffer, x, sMask, zMask, cMask);
 				}
-				}
 
 				#if PERF_PROFILE
 					cycles[PERF_ROP] += Ticks() - ropTime;
@@ -2474,9 +2471,4 @@ namespace sw
 
 		return Min(Max(linear, Float4(0.0f)), Float4(1.0f));
 	}
-
-	bool PixelRoutine::colorUsed()
-	{
-		return state.colorWriteMask || state.alphaToCoverage || (spirvShader && spirvShader->getModes().ContainsKill);
-	}
 }

src/Pipeline/PixelRoutine.hpp

@@ -89,8 +89,6 @@ namespace sw
 
 		void writeDepth32F(Pointer<Byte> &zBuffer, int q, Int &x, Float4 &z, Int &zMask);
 		void writeDepth16(Pointer<Byte> &zBuffer, int q, Int &x, Float4 &z, Int &zMask);
-
-		bool colorUsed();
 	};
 }
 

src/Pipeline/SpirvShader.hpp

@@ -511,6 +511,11 @@ namespace sw
 			return inputBuiltins.find(b) != inputBuiltins.end();
 		}
 
+		bool hasBuiltinOutput(spv::BuiltIn b) const
+		{
+			return outputBuiltins.find(b) != outputBuiltins.end();
+		}
+
 		struct Decorations
 		{
 			int32_t Location = -1;