Fix alignment assumption. Fixes issue 132.

src/nvimage/DirectDrawSurface.cpp

@@ -1196,13 +1196,9 @@ uint DirectDrawSurface::mipmapSize(uint mipmap) const
 	{
 		nvDebugCheck((header.pf.flags & DDPF_RGB) || (header.pf.flags & DDPF_LUMINANCE));
 		
-		// Align pixels to bytes.
-		uint byteCount = (header.pf.bitcount + 7) / 8;
-		
-		// Align pitch to 4 bytes.
-		uint pitch = 4 * ((w * byteCount + 3) / 4);
-		
-		return pitch * h * d;
+        uint pitch = computePitch(w, header.pf.bitcount, 8); // Asuming 8 bit alignment, which is the same D3DX expects.
+
+        return pitch * h * d;
 	}
 }
 

src/nvimage/nvimage.h

@@ -19,4 +19,14 @@
 #define NVIMAGE_CLASS
 #endif
 
+
+// Some utility functions:
+
+inline uint computePitch(uint w, uint bitsize, uint alignment)
+{
+	return ((w * bitsize +  8 * alignment - 1) / (8 * alignment)) * alignment;
+}
+
+
+
 #endif // NV_IMAGE_H

src/nvtt/CompressRGB.cpp

@@ -37,12 +37,6 @@ using namespace nvtt;
 namespace 
 {
 
-    inline uint computePitch(uint w, uint bitsize)
-    {
-        // Align to 8 bits.
-        return w * ((bitsize + 7) / 8);
-    }
-
     inline void convert_to_a8r8g8b8(const void * src, void * dst, uint w)
     {
         memcpy(dst, src, 4 * w);
@@ -86,7 +80,7 @@ void nv::compressRGB(const Image * image, const OutputOptions::Private & outputO
     PixelFormat::maskShiftAndSize(amask, &ashift, &asize);
 
     // Determine pitch.
-    uint pitch = computePitch(w, compressionOptions.bitcount);
+    uint pitch = computePitch(w, compressionOptions.bitcount, 8);
 
     uint8 * dst = (uint8 *)mem::malloc(pitch + 4);
 

src/nvtt/Compressor.cpp

@@ -74,18 +74,10 @@ namespace
 		return 0;
 	}
 
-	inline uint computePitch(uint w, uint bitsize)
-	{
-		uint p = w * ((bitsize + 7) / 8);
-
-		// Align to 32 bits.
-		return ((p + 3) / 4) * 4;
-	}
-
 	static int computeImageSize(uint w, uint h, uint d, uint bitCount, Format format)
 	{
 		if (format == Format_RGBA) {
-			return d * h * computePitch(w, bitCount);
+			return d * h * computePitch(w, bitCount, 8);
 		}
 		else {
 			// @@ Handle 3D textures. DXT and VTC have different behaviors.
@@ -346,7 +338,7 @@ bool Compressor::Private::outputHeader(const InputOptions::Private & inputOption
 
 	if (compressionOptions.format == Format_RGBA)
 	{
-		header.setPitch(computePitch(inputOptions.targetWidth, compressionOptions.bitcount));
+		header.setPitch(computePitch(inputOptions.targetWidth, compressionOptions.bitcount, 8));
 		header.setPixelFormat(compressionOptions.bitcount, compressionOptions.rmask, compressionOptions.gmask, compressionOptions.bmask, compressionOptions.amask);
 	}
 	else