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Using premultiplied alpha avoids this. Jim Blinn's books from the 90s give a very thoughtful treatment of the topic.

The Porter and Duff compositing paper is good, too.

One clarification, though: With premultiplied colors, something like (1,1,1,0) is either illegal or a light source. It's not a valid normal color.

But then you can do additive blending without changing blend modes - or even some additive and some standard transparency modes in the same sprite!

Entirely false in that it is indeed a completely valid combination. See luminescent pixels in the Porter Duff paper. It represents a pixel that has no occlusion and is emitting.

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