texconv: added cases where BC4/BC5 need to decompress to 4 channels - #723
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nadaOuf
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Aug 4, 2026
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Normally BC4 decompresses to R8 and BC5 decompresses to R8G8 to match the channel count of those formats. If doing swizzle operations for the B or A channel, inverting the G channel for BC4, or if reconstructing the B channel for normal maps, we need room for the new data or it gets lost. For cases where you are converting BC5 to DXT5nm, it also needs expanded to 4 channels.
This change has the decompressing going to RGBA32 (4-channels) in these cases rather than the narrower format.