- adjustments and fixes for alphatextures:

* Instead of using the red channel it now uses the grayscale value. While slower in a few situations, it is also more precise and makes the feature more useful.
* For paletted textures do not use the index as alpha anymore but the actual grayscaled color. This is again to make the feature more consistent and useful.
* To compensate for the above there is now a list of hashes for known alpha textures in patch format, so that they don't get broken.
* IMGZ is now considered a grayscale format. There's only two known textures that use IMGZ for something else than crosshairs and those are explicitly handled.
* several smaller fixes.
* the actual color conversion functions for paletted output are now consolidated in a small number of inlines so that future changes are easier to do.

Note: This hasn't been tested yet and will need further changes in the hardware rendering code. As it is it is not production-ready.

src/textures/texture.cpp

@@ -754,7 +754,7 @@ void FTexture::FillBuffer(uint8_t *buff, int pitch, int height, FTextureFormat f
 	{
 	case TEX_Pal:
 	case TEX_Gray:
-		pix = GetPixels(DefaultRenderStyle());
+		pix = GetPixels(fmt == TEX_Pal? DefaultRenderStyle() : LegacyRenderStyles[STYLE_Shaded]);
 		stride = pitch - w;
 		for (y = 0; y < h; ++y)
 		{