Function ilNVidiaCompressDXTFile

DevIL/src-IL/src/il_nvidia.cpp:172–216

Compresses data to a DXT format using nVidia's Texture Tools library. This version is supposed to be completely internal to DevIL. The data must be in unsigned byte RGBA format. The alpha channel will be ignored if DxtType is IL_DXT1.

//  This version is supposed to be completely internal to DevIL.
//  The data must be in unsigned byte RGBA format.  The alpha channel will be ignored if DxtType is IL_DXT1.
ILuint ilNVidiaCompressDXTFile(ILubyte *Data, ILuint Width, ILuint Height, ILuint Depth, ILenum DxtFormat)
{
	ILuint FilePos = itellw();

	// The nVidia Texture Tools library does not support volume textures yet.
	if (Depth != 1) {
		ilSetError(IL_INVALID_PARAM);
		return 0;
	}

	InputOptions inputOptions;
	inputOptions.setTextureLayout(TextureType_2D, Width, Height);
	inputOptions.setMipmapData(Data, Width, Height);
	inputOptions.setMipmapGeneration(false, -1);  //@TODO: Use this in certain cases.

	OutputOptions outputOptions;
	ilOutputHandlerFile outputHandler(Width, Height, DxtFormat);
	outputOptions.setOutputHeader(false);
	outputOptions.setOutputHandler(&outputHandler);

	CompressionOptions compressionOptions;
	switch (DxtFormat)
	{
		case IL_DXT1:
			compressionOptions.setFormat(Format_DXT1);
			break;
		case IL_DXT1A:
			compressionOptions.setFormat(Format_DXT1a);
			break;
		case IL_DXT3:
			compressionOptions.setFormat(Format_DXT1);
			break;
		case IL_DXT5:
			compressionOptions.setFormat(Format_DXT5);
			break;
		default:  // Does not support DXT2 or DXT4.
			ilSetError(IL_INVALID_PARAM);
			break;
	}

	Compressor compressor;
	compressor.process(inputOptions, compressionOptions, outputOptions);

	return itellw() - FilePos;  // Return the number of characters written.
}

#else
// Let's have this so that the function is always created and exported, even if it does nothing.