Fix clamping of NaN values.

src/Common/Math.hpp

@@ -75,7 +75,7 @@ namespace sw
 	}
 
 	template <typename destType, typename sourceType>
-	destType bitCast(const sourceType &source)
+	destType bit_cast(const sourceType &source)
 	{
 		union
 		{
@@ -196,6 +196,26 @@ namespace sw
 		return clamp(x, 0.0f, 1.0f);
 	}
 
+	// Bit-cast of a floating-point value into a two's complement integer representation.
+	// This makes floating-point values comparable as integers.
+	inline int32_t float_as_twos_complement(float f)
+	{
+		// IEEE-754 floating-point numbers are sorted by magnitude in the same way as integers,
+		// except negative values are like one's complement integers. Convert them to two's complement.
+		int32_t i = bit_cast<int32_t>(f);
+		return (i < 0) ? (0x7FFFFFFF - i) : i;
+	}
+
+	// 'Safe' clamping operation which always returns a value between min and max (inclusive).
+	inline float clamp_s(float x, float min, float max)
+	{
+		// NaN values can't be compared directly
+		if(float_as_twos_complement(x) < float_as_twos_complement(min)) x = min;
+		if(float_as_twos_complement(x) > float_as_twos_complement(max)) x = max;
+
+		return x;
+	}
+
 	inline int ceilPow2(int x)
 	{
 		int i = 1;

src/OpenGL/compiler/Intermediate.cpp

@@ -1974,7 +1974,7 @@ TIntermTyped* TIntermConstantUnion::fold(TOperator op, TIntermTyped* constantNod
 				case EOpFloatBitsToInt:
 					switch(basicType) {
 					case EbtFloat:
-						tempConstArray[i].setIConst(sw::bitCast<int>(unionArray[i].getFConst()));
+						tempConstArray[i].setIConst(sw::bit_cast<int>(unionArray[i].getFConst()));
 						type.setBasicType(EbtInt);
 						break;
 					default:
@@ -1986,7 +1986,7 @@ TIntermTyped* TIntermConstantUnion::fold(TOperator op, TIntermTyped* constantNod
 				case EOpFloatBitsToUint:
 					switch(basicType) {
 					case EbtFloat:
-						tempConstArray[i].setUConst(sw::bitCast<unsigned int>(unionArray[i].getFConst()));
+						tempConstArray[i].setUConst(sw::bit_cast<unsigned int>(unionArray[i].getFConst()));
 						type.setBasicType(EbtUInt);
 						break;
 					default:
@@ -1997,7 +1997,7 @@ TIntermTyped* TIntermConstantUnion::fold(TOperator op, TIntermTyped* constantNod
 				case EOpIntBitsToFloat:
 					switch(basicType) {
 					case EbtInt:
-						tempConstArray[i].setFConst(sw::bitCast<float>(unionArray[i].getIConst()));
+						tempConstArray[i].setFConst(sw::bit_cast<float>(unionArray[i].getIConst()));
 						type.setBasicType(EbtFloat);
 						break;
 					default:
@@ -2008,7 +2008,7 @@ TIntermTyped* TIntermConstantUnion::fold(TOperator op, TIntermTyped* constantNod
 				case EOpUintBitsToFloat:
 					switch(basicType) {
 					case EbtUInt:
-						tempConstArray[i].setFConst(sw::bitCast<float>(unionArray[i].getUConst()));
+						tempConstArray[i].setFConst(sw::bit_cast<float>(unionArray[i].getUConst()));
 						type.setBasicType(EbtFloat);
 						break;
 					default:

src/Renderer/PixelProcessor.cpp

@@ -95,11 +95,11 @@ namespace sw
 
 		if(index < 8)   // ps_1_x constants
 		{
-			// FIXME: Compact into generic function
-			short x = iround(4095 * clamp(value[0], -1.0f, 1.0f));
-			short y = iround(4095 * clamp(value[1], -1.0f, 1.0f));
-			short z = iround(4095 * clamp(value[2], -1.0f, 1.0f));
-			short w = iround(4095 * clamp(value[3], -1.0f, 1.0f));
+			// TODO: Compact into generic function
+			short x = iround(4095 * clamp_s(value[0], -1.0f, 1.0f));
+			short y = iround(4095 * clamp_s(value[1], -1.0f, 1.0f));
+			short z = iround(4095 * clamp_s(value[2], -1.0f, 1.0f));
+			short w = iround(4095 * clamp_s(value[3], -1.0f, 1.0f));
 
 			cW[index][0][0] = x;
 			cW[index][0][1] = x;

src/System/Math.hpp

@@ -75,7 +75,7 @@ namespace sw
 	}
 
 	template <typename destType, typename sourceType>
-	destType bitCast(const sourceType &source)
+	destType bit_cast(const sourceType &source)
 	{
 		union
 		{
@@ -196,6 +196,26 @@ namespace sw
 		return clamp(x, 0.0f, 1.0f);
 	}
 
+	// Bit-cast of a floating-point value into a two's complement integer representation.
+	// This makes floating-point values comparable as integers.
+	inline int32_t float_as_twos_complement(float f)
+	{
+		// IEEE-754 floating-point numbers are sorted by magnitude in the same way as integers,
+		// except negative values are like one's complement integers. Convert them to two's complement.
+		int32_t i = bit_cast<int32_t>(f);
+		return (i < 0) ? (0x7FFFFFFF - i) : i;
+	}
+
+	// 'Safe' clamping operation which always returns a value between min and max (inclusive).
+	inline float clamp_s(float x, float min, float max)
+	{
+		// NaN values can't be compared directly
+		if(float_as_twos_complement(x) < float_as_twos_complement(min)) x = min;
+		if(float_as_twos_complement(x) > float_as_twos_complement(max)) x = max;
+
+		return x;
+	}
+
 	inline int ceilPow2(int x)
 	{
 		int i = 1;