Add support for luminance flag. Fixes issue 126.

src/nvimage/DirectDrawSurface.cpp

@@ -662,8 +662,14 @@ void DDSHeader::setPixelFormat(uint bitcount, uint rmask, uint gmask, uint bmask
 	nvCheck((gmask & amask) == 0);
 	nvCheck((bmask & amask) == 0);
 
-	this->pf.flags = DDPF_RGB;
-
+	if (rmask > 0 && gmask == 0 && bmask == 0)
+	{
+		this->pf.flags = DDPF_LUMINANCE;
+	}
+	else
+	{
+		this->pf.flags = DDPF_RGB;
+	}
 	if (amask != 0) {
 		this->pf.flags |= DDPF_ALPHAPIXELS;
 	}
@@ -816,9 +822,9 @@ bool DirectDrawSurface::isSupported() const
 				return false;
 			}
 		}
-		else if (header.pf.flags & DDPF_RGB)
+		else if ((header.pf.flags & DDPF_RGB) || (header.pf.flags & DDPF_LUMINANCE))
 		{
-			// All RGB formats are supported now.
+			// All RGB and luminance formats are supported now.
 		}
 		else
 		{
@@ -937,7 +943,7 @@ void DirectDrawSurface::mipmap(Image * img, uint face, uint mipmap)
 	
 	img->allocate(w, h);
 	
-	if (header.pf.flags & DDPF_RGB) 
+	if ((header.pf.flags & DDPF_RGB) || (header.pf.flags & DDPF_LUMINANCE)) 
 	{
 		readLinearImage(img);
 	}
@@ -1172,7 +1178,7 @@ uint DirectDrawSurface::mipmapSize(uint mipmap) const
 	}
 	else
 	{
-		nvDebugCheck(header.pf.flags & DDPF_RGB);
+		nvDebugCheck((header.pf.flags & DDPF_RGB) || (header.pf.flags & DDPF_LUMINANCE));
 		
 		// Align pixels to bytes.
 		uint byteCount = (header.pf.bitcount + 7) / 8;
@@ -1242,6 +1248,7 @@ void DirectDrawSurface::printInfo() const
 	printf("Pixel Format:\n");
 	printf("\tFlags: 0x%.8X\n", header.pf.flags);
 	if (header.pf.flags & DDPF_RGB) printf("\t\tDDPF_RGB\n");
+	if (header.pf.flags & DDPF_LUMINANCE) printf("\t\DDPF_LUMINANCE\n");
 	if (header.pf.flags & DDPF_FOURCC) printf("\t\tDDPF_FOURCC\n");
 	if (header.pf.flags & DDPF_ALPHAPIXELS) printf("\t\tDDPF_ALPHAPIXELS\n");
 	if (header.pf.flags & DDPF_ALPHA) printf("\t\tDDPF_ALPHA\n");

src/nvtt/tools/compress.cpp

@@ -143,6 +143,7 @@ int main(int argc, char *argv[])
 	bool nocuda = false;
 	bool silent = false;
 	bool bc1n = false;
+	bool luminance = false;
 	nvtt::Format format = nvtt::Format_BC1;
 
 	const char * externalCompressor = NULL;
@@ -195,6 +196,11 @@ int main(int argc, char *argv[])
 		{
 			format = nvtt::Format_RGB;
 		}
+		else if (strcmp("-lumi", argv[i]) == 0)
+		{
+			luminance = true;
+			format = nvtt::Format_RGB;
+		}
 		else if (strcmp("-bc1", argv[i]) == 0)
 		{
 			format = nvtt::Format_BC1;
@@ -286,6 +292,7 @@ int main(int argc, char *argv[])
 		printf("  -fast    \tFast compression.\n");
 		printf("  -nocuda  \tDo not use cuda compressor.\n");
 		printf("  -rgb     \tRGBA format\n");
+		printf("  -lumi    \tLUMINANCE format\n");
 		printf("  -bc1     \tBC1 format (DXT1)\n");
 		printf("  -bc1n    \tBC1 normal map format (DXT1nm)\n");
 		printf("  -bc1a    \tBC1 format with binary alpha (DXT1a)\n");
@@ -398,6 +405,10 @@ int main(int argc, char *argv[])
 
 	nvtt::CompressionOptions compressionOptions;
 	compressionOptions.setFormat(format);
+	if (luminance)
+	{
+		compressionOptions.setPixelFormat(8, 0xff, 0, 0, 0);
+	}
 	if (fast)
 	{
 		compressionOptions.setQuality(nvtt::Quality_Fastest);