Fix errors in color transforms.

Add support for color offsets.
Add support for special swizzles that select default const values.

src/nvimage/FloatImage.cpp

@@ -242,7 +242,7 @@ void FloatImage::exponentiate(uint base_component, uint num, float power)
 }
 
 /// Apply linear transform.
-void FloatImage::transform(uint base_component, const Matrix & m)
+void FloatImage::transform(uint base_component, const Matrix & m, Vector4::Arg offset)
 {
 	nvCheck(base_component + 4 <= m_componentNum);
 
@@ -255,7 +255,7 @@ void FloatImage::transform(uint base_component, const Matrix & m)
 
 	for (uint i = 0; i < size; i++)
 	{
-		Vector4 color = nv::transform(m, Vector4(*r, *g, *b, *a));
+		Vector4 color = nv::transform(m, Vector4(*r, *g, *b, *a)) + offset;
 
 		*r++ = color.x();
 		*g++ = color.y();
@@ -267,14 +267,19 @@ void FloatImage::transform(uint base_component, const Matrix & m)
 void FloatImage::swizzle(uint base_component, uint r, uint g, uint b, uint a)
 {
 	nvCheck(base_component + 4 <= m_componentNum);
+	nvCheck(r < 7 && g < 7 && b < 7 && a < 7);
 
 	const uint size = m_width * m_height;
 
-	float * c[4];
+	float consts[] = { 1.0f, 0.0f, -1.0f };
+	float * c[7];
 	c[0] = this->channel(base_component + 0);
 	c[1] = this->channel(base_component + 1);
 	c[2] = this->channel(base_component + 2);
 	c[3] = this->channel(base_component + 3);
+	c[4] = consts;
+	c[5] = consts + 1;
+	c[6] = consts + 2;
 
 	for (uint i = 0; i < size; i++)
 	{

src/nvimage/FloatImage.h

@@ -63,7 +63,7 @@ public:
 	NVIMAGE_API void toGamma(uint base_component, uint num, float gamma = 2.2f);
 	NVIMAGE_API void exponentiate(uint base_component, uint num, float power);
 	
-	NVIMAGE_API void transform(uint base_component, const Matrix & m);
+	NVIMAGE_API void transform(uint base_component, const Matrix & m, Vector4::Arg offset);
 	NVIMAGE_API void swizzle(uint base_component, uint r, uint g, uint b, uint a);
 	
 	NVIMAGE_API FloatImage * fastDownSample() const;

src/nvtt/Compressor.cpp

@@ -665,7 +665,13 @@ void Compressor::Private::processInputImage(Mipmap & mipmap, const InputOptions:
 			FloatImage * image = mipmap.asFloatImage();
 			nvDebugCheck(image != NULL);
 
-			image->transform(0, inputOptions.linearTransform);
+			Vector4 offset(
+				inputOptions.colorOffsets[0],
+				inputOptions.colorOffsets[1],
+				inputOptions.colorOffsets[2],
+				inputOptions.colorOffsets[3]);
+
+			image->transform(0, inputOptions.linearTransform, offset);
 		}
 		else if (inputOptions.colorTransform == ColorTransform_Swizzle)
 		{

src/nvtt/InputOptions.cpp

@@ -103,6 +103,8 @@ void InputOptions::reset()
 	
 	m.colorTransform = ColorTransform_None;
 	m.linearTransform = Matrix(identity);
+	for (int i = 0; i < 4; i++) m.colorOffsets[i] = 0;
+	for (int i = 0; i < 4; i++) m.swizzleTransform[i] = i;
 
 	m.generateMipmaps = true;
 	m.maxLevel = -1;
@@ -344,16 +346,27 @@ void InputOptions::setLinearTransform(int channel, float w0, float w1, float w2,
 {
 	nvCheck(channel >= 0 && channel < 4);
 
-	Vector4 w(w0, w1, w2, w3);
-	//m.linearTransform.setRow(channel, w);
+	m.linearTransform(0, channel) = w0;
+	m.linearTransform(1, channel) = w1;
+	m.linearTransform(2, channel) = w2;
+	m.linearTransform(3, channel) = w3;
+}
+
+void InputOptions::setLinearTransform(int channel, float w0, float w1, float w2, float w3, float offset)
+{
+	nvCheck(channel >= 0 && channel < 4);
+
+	setLinearTransform(channel, w0, w1, w2, w3);
+
+	m.colorOffsets[channel] = offset;
 }
 
 void InputOptions::setSwizzleTransform(int x, int y, int z, int w)
 {
-	nvCheck(x >= 0 && x < 3);
-	nvCheck(y >= 0 && y < 3);
-	nvCheck(z >= 0 && z < 3);
-	nvCheck(w >= 0 && w < 3);
+	nvCheck(x >= 0 && x <= 6);
+	nvCheck(y >= 0 && y <= 6);
+	nvCheck(z >= 0 && z <= 6);
+	nvCheck(w >= 0 && w <= 6);
 	
 	m.swizzleTransform[0] = x;
 	m.swizzleTransform[1] = y;

src/nvtt/InputOptions.h

@@ -57,6 +57,7 @@ namespace nvtt
 		// Color transform.
 		ColorTransform colorTransform;
 		nv::Matrix linearTransform;
+		float colorOffsets[4];
 		uint swizzleTransform[4];
 		
 		// Mipmap generation options.

src/nvtt/nvtt.h

@@ -220,9 +220,10 @@ namespace nvtt
 		NVTT_API void setNormalFilter(float sm, float medium, float big, float large);
 		NVTT_API void setNormalizeMipmaps(bool b);
 		
-		// Set color transforms. @@ Not implemented!
+		// Set color transforms.
 		NVTT_API void setColorTransform(ColorTransform t);
 		NVTT_API void setLinearTransform(int channel, float w0, float w1, float w2, float w3);
+		NVTT_API void setLinearTransform(int channel, float w0, float w1, float w2, float w3, float offset);
 		NVTT_API void setSwizzleTransform(int x, int y, int z, int w);
 		
 		// Set resizing options.