[metapost] metafun: transparency (opacity) that doesn't add up

Stephan Hennig mailing_list at arcor.de
Thu Apr 27 18:59:21 CEST 2006

Mojca Miklavec schrieb:

>> [transparency]
> I don't know any other references except "common-sense". If you draw
> two lines one over another, the color will sum up in the intersection.

This is true for, e.g., transparency methods "normal" or "multiply".
However, with methods "exclusion" or "difference" I think you can get
quite different effects than just "summing up" colors. My hope was that
there is some smart transparency method or parameter set that recognizes
intersections with the same color and does nothing in that case.

> If you draw only one "object" (the cross in your case), then the whole
> object will be draw with the same color.

It might be the behavior expected by common-sense. But I wouldn't have
expected that. :) That's why I'd be glad to see that behavior defined
in, maybe, some pdf specs. Anyway, thanks for your responses, Mojca!

Stephan Hennig

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