Some pitch alignment fixes. Fixes issue 168.

src/nvimage/DirectDrawSurface.cpp

@@ -1419,7 +1419,7 @@ uint DirectDrawSurface::mipmapSize(uint mipmap) const
     {
         nvDebugCheck((header.pf.flags & DDPF_RGB) || (header.pf.flags & DDPF_LUMINANCE));
 
-        uint pitch = computePitch(w, header.pf.bitcount, 8); // Asuming 8 bit alignment, which is the same D3DX expects.
+        uint pitch = computeBytePitch(w, header.pf.bitcount, 8); // Asuming 8 bit alignment, which is the same D3DX expects.
 
         return pitch * h * d;
     }

src/nvimage/ErrorMetric.cpp

@@ -321,6 +321,7 @@ float nv::spatialCieLabError(const FloatImage * img0, const FloatImage * img1)
     */
     // @@ Measure Delta E between lab0 and lab1.
 
+    return 0.0f;
 }
 
 

src/nvimage/nvimage.h

@@ -4,7 +4,9 @@
 #ifndef NV_IMAGE_H
 #define NV_IMAGE_H
 
-#include <nvcore/nvcore.h>
+#include "nvcore/nvcore.h"
+#include "nvcore/Debug.h" // nvDebugCheck
+#include "nvcore/Utils.h" // isPowerOfTwo
 
 // Function linkage
 #if NVIMAGE_SHARED
@@ -21,13 +23,27 @@
 #endif
 
 
-// Some utility functions:
+namespace nv {
 
-inline uint computePitch(uint w, uint bitsize, uint alignment)
+    // Some utility functions:
-{
-	return ((w * bitsize +  8 * alignment - 1) / (8 * alignment)) * alignment;
-}
 
+    inline uint computeBitPitch(uint w, uint bitsize, uint alignmentInBits)
+    {
+        nvDebugCheck(isPowerOfTwo(alignmentInBits));
 
+        return ((w * bitsize +  alignmentInBits - 1) / alignmentInBits) * alignmentInBits;
+    }
+
+    inline uint computeBytePitch(uint w, uint bitsize, uint alignmentInBits)
+    {
+        nvDebugCheck(alignmentInBits >= 8);
+
+        uint pitch = computeBitPitch(w, bitsize, alignmentInBits);
+
+        return (pitch + 7) / 8;
+    }
+
+
+} // nv namespace
 
 #endif // NV_IMAGE_H

src/nvtt/CompressionOptions.cpp

@@ -63,7 +63,7 @@ void CompressionOptions::reset()
     m.asize = 8;
 	
     m.pixelType = PixelType_UnsignedNorm;
-    m.pitchAlignment = 1;
+    m.pitchAlignment = 8;
 
     m.enableColorDithering = false;
     m.enableAlphaDithering = false;

src/nvtt/CompressorRGB.cpp

@@ -188,11 +188,12 @@ void PixelFormatConverter::compress(nvtt::AlphaMode /*alphaMode*/, uint w, uint
         }
     }
 
-    const uint pitch = computePitch(w, bitCount, compressionOptions.pitchAlignment);
+    const uint pitch = computeBitPitch(w, bitCount, compressionOptions.pitchAlignment);
+    const uint pitchInBytes = (pitch + 7) / 8;
     const uint wh = w * h;
 
     // Allocate output scanline.
-    uint8 * const dst = malloc<uint8>(pitch);
+    uint8 * const dst = malloc<uint8>(pitchInBytes);
 
     for (uint y = 0; y < h; y++)
     {
@@ -251,14 +252,15 @@ void PixelFormatConverter::compress(nvtt::AlphaMode /*alphaMode*/, uint w, uint
 
         // Zero padding.
         stream.align(compressionOptions.pitchAlignment);
-        nvDebugCheck(stream.ptr == dst + pitch);
+        nvDebugCheck(stream.ptr == dst + pitchInBytes);
 
-        /*for (uint x = w * byteCount; x < pitch; x++)
+        /*for (uint x = w * byteCount; x < pitchInBytes; x++)
         {
                 *(dst + x) = 0;
         }*/
 
-        outputOptions.writeData(dst, pitch);
+        // @@ This code does not truly support less than byte-aligned textures.
+        outputOptions.writeData(dst, pitchInBytes);
     }
 
     free(dst);

src/nvtt/Context.cpp

@@ -479,7 +479,7 @@ bool Compressor::Private::outputHeader(nvtt::TextureType textureType, int w, int
             if (compressionOptions.format == Format_RGBA)
             {
                 // Get output bit count.
-                header.setPitch(computePitch(w, compressionOptions.getBitCount(), compressionOptions.pitchAlignment));
+                header.setPitch(computeBytePitch(w, compressionOptions.getBitCount(), compressionOptions.pitchAlignment));
 
                 if (compressionOptions.pixelType == PixelType_Float)
                 {

src/nvtt/TexImage.cpp

@@ -109,10 +109,10 @@ uint nv::countMipmaps(uint w, uint h, uint d)
     return mipmap + 1;
 }
 
-uint nv::computeImageSize(uint w, uint h, uint d, uint bitCount, uint alignment, Format format)
+uint nv::computeImageSize(uint w, uint h, uint d, uint bitCount, uint pitchAlignmentInBits, Format format)
 {
     if (format == Format_RGBA) {
-        return d * h * computePitch(w, bitCount, alignment);
+        return d * h * computeBytePitch(w, bitCount, pitchAlignmentInBits);
     }
     else {
         // @@ Handle 3D textures. DXT and VTC have different behaviors.