Ah, premultiplied alpha! I haven't thought about that in years. For reference, here's the original paper by Porter and Duff: https://dl.acm.org/doi/10.1145/9

Ah, premultiplied alpha! I haven't thought about that in years. For reference, here's the original paper by Porter and Duff: https://dl.acm.org/doi/10.1145/964965.808606 https://dl.acm.org/doi/10.1145/964965.808606