Re: [AD] Patch for the documentation of polygon_z_normal()

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Robert Ohannessian wrote:
That's probably too difficult for a beginners guide. You can't just do
camera->poly dot normal > 0 and have that work, you need to compare
against a range of values (which can be negative), based on the
projection transform, and clip against that.


Now that I think about it, this can't work either. You need to have your
geometry in screen-space.


If it's too complicated for the allegro docs, perhaps it should go in one of the examples.

So what would be a good method for back-face culling without first converting into screen space? The advantage this has is that it saves a persp_project() call for any vertices who'se polys are completely obscured.

If we can come up with a solution that we all can agree on, I'd recommend we update exscn3d.exe to use it as it uses more vertices than the other examples, and it uses 3D clipping as well.


AE.




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