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Perhaps I'm not being clear. In WPF/Avalon we aimed to have a generic scene graph. We were also looking to cache intermediate nodes in the scene graph and do
by jbeda 14y ago
Perhaps I'm not being clear.
In WPF/Avalon we aimed to have a generic scene graph. We were also looking to cache intermediate nodes in the scene graph and do composition of a transform on those nodes. This was to prevent the need to completely rerender a complex scene graph tree on every frame if the transformations were small enough.
The issue arises when you want to composite text onto a background and then further composite that result onto another image. If there is any transparency under the text in the intermediate cached image, cleartype/subpixel antialiasing breaks down.
So -- it is straightforward to figure out how to do a subpixel mask composition, but it is much harder when you want to take that result and composite it further.
This was a while ago so perhaps I'm misremembering though :)
- ori_b 14y agoOk, I think that makes sense. Just to make sure I understood, the problem isn't the text itself, but what happens when the destination surface has an alpha channel or is transformed?
- jbeda 14y agoExactly -- if you composite into a buffer without an alpha channel (such as the final frame buffer) you are cool. If you want the destination to be able to alpha composite further on, you have trouble/complexity.