Particles: premultiply the texel when the texture arrived straight - #31
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SDLWorldQuadRenderer blends (ONE, 1-SRC_ALPHA) and worldquad premultiplies the vertex colour, so everything downstream of that shader -- the blend factors, the fog rules, the soft-depth fade -- is written for a premultiplied source. The DDS decoder produces one (Render/src/DDSImage.cpp, to stop bilinear filtering bleeding transparent-texel colour into opaque edges). A .tga or an .avi frame does not, and in both games every texture this renderer draws is one of those: particle sprites, coast foam, the sun and moon, the rain. Left straight, a texel's colour enters at full strength however transparent it is, so the soft border of a smoke puff draws as hard as its middle and the sprite reads as a bright square with a picture in it. cTexture now records which of the two its reload produced and the renderer passes that to the shader, which premultiplies where the decoder did not. Keying off the decoder rather than the file extension keeps the one exception honest: a specular or bump map is deliberately not premultiplied, its alpha being power or nothing rather than opacity. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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