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Drakken255

HLSL: How to calculate pixel color by overlay texture's color and alpha.

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I am trying to change the texture output by taking each pixel and calculating to color based on an overlay image's pixel color and alpha, but I don't know the algorithm for this.

EDIT: Figured it out.

Out.color = new.color * new.alpha + old.color * (1 - new.alpha)

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Are you sure it shouln't be:

Out.color = new.color * new.alpha + old.color * (1 - new.alpha)

This way, you get the transparent parts of "old" and the correctly the opaque parts of "new". Perhaps you have set an alpha value of 0.0f in your "old" by mistake?

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[quote name='SamiHuutoniemi']
Out.color = new.color * new.alpha + old.color * (1 - new.alpha)


They're... kinda... the same thing...

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