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mogu
05-02-2005, 09:40 PM
Is it possible to calcualte a good near clip using only field-of-view and far clip?

I have som simple calcuations that increase or decrease my near clip when I change my fov. This I do to prevent z buffer flickering when I look at 3D objects. The function is linear, so it will not work on all combinations of fov and far clip since z-buffer values are exponential, giving more z-buffer precision to objects close to near clip.

Is it possible to make a function that calculate a near clip that does not cause z buffer flicker using far clip and fov as input, or is this something that must be customized for every far clip and fov?

any ideas?

T101
05-02-2005, 10:09 PM
I'd say the FOV has virtually no influence (except for making the artifacts bigger).

The main cause of artifacts is the number of bits in the z-buffer and the nearvalue.

Play around with this for a bit:
http://www.sjbaker.org/steve/omniv/love_your_z_buffer.html

Basically you'll need to determine the precision of far away geometry that you still want to be rendered correctly, and pick a suitable near-value for that.

And I suppose using some kind of LOD algorithm to reduce polygon detail at a distance should also improve the visual quality of far away objects.

mogu
05-03-2005, 09:51 PM
Thanks! I have bookmarked the page. I really cleared things up...