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TerranFury

Multipass rendering without re-transforming scene

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The title should explain essentially what I mean to ask: Is it possible to render a polygon using multiple blended textures in multiple passes without re-transforming the polygon? In theory, multipass rendering should only hit your fillrate, and not your CPU. How can I do that in practice?

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Just do all your transformations and store the results in arrays. After that, render you arrays several times with different textures.

But note that almost all nowadays cards can use multitexturing which does not hit your fillrate as much as rendering the scene several times.

However it''s not included in the standard OpenGL implementation. Check ARBMultiTexture.

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I never tried this, so it may even be slower, but you can try sticking each glBegin/End block in a NON-compiled display list on the fly. Compiling can''t be done real time. That way the data stays in the card.

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quote:
Original post by TerranFury
That will take care of translation and rotation. But how can I perspective transform the geometry from world space to 2d space only once?


With multi texturing projections are computed only one time.

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