TGA uses BGR(A)8, stored in memory in that order. Irrlicht typically expects 0xAARRGGBB, which depends on endianness.
(This means that on little endian, no [B][G][R][A] -> 0xAARRGGBB conversion needs to be done, but Irrlicht was swapping the bytes.)
This makes both conversion functions consistently convert from [B][G][R]([A]) to 0xAARRGGBB (SColor), documents them properly and moves them to CImageLoaderTGA.cpp
so no poor soul shall be fooled by them in the near future.
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Co-authored-by: Ælla Chiana Moskopp <erle@dieweltistgarnichtso.net>
The branch removed in this patch handled color format A1R5G5B5 specially
when creating a texture from a TGA type 1 file, i.e. an image that has a
colormap. It did not handle the 1-bit alpha channel correctly, rendering
transparent pixels black instead.
Since the colormap is converted to A8R8G8B8 earlier anyways, the code
for the general case is able to handle this scenario already – at the
expense of making the created texture use twice as much GPU memory as
necessary.
