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View Full Version : clipping question/ display errors



Caltus
07-10-2002, 08:58 PM
Hi,
I was just wondering if anyone does know what causes clipping errors to begin to occur from a distance and up close they go away.
sorry i dont have a picture but the distortion occurs when using lazy or easier methods for scenes. rather than clipping the edge to match the intersection, the processor does not clip straight. it shows as a wave pattern whis is more prominant the farther you move away from it.
it most happens when i make a water tile and have land cut thru. I like to know if there is a function to fine tune this, or do i have to resort to manual clipping. what is wierd is that it does not appear all the time but is more opt to happen when normals are similar for the intersecting pieces. I know it happens on alot a cards. a generic 8mb. my previous tnt2/ geforce2 and now my gforce 4 also.
any info would be great. Thanks

ioquan
07-10-2002, 09:13 PM
This is called "z fighting". As you get further away from something, the depth buffer becomes less and less accurate, causing objects which are behind to be drawn partially in front. To fix this, you need to make your near clip plane bigger (greater than 1 for sure - possibly 10 or more). The higher the value of (far/near) is, the more problems you will have with z fighting. The near and far clip panes are set up in your call to gluPerspective or glFrustum.