When adding a decal bitmap with alpha channel, should I turn premultiplied on or off by default? I ask, because I noticed that lightmap seems to be misled when premultiplied is on.
This image shows what I mean: around the bitmap, the lightmap shows brighter than it should.
That depends on if the image is saved premultiplied or not. If you get bright edges with premultiplied the image probably has a straight alpha, not a premultiplied.