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Clip Planes

Iso surfaces are nested (onion shells). To see the inner shells it is often necessary to remove tissue that is occluding the inner parts. This is done via:

A clip plane removes the geometry on one side of the plane.

With OpenGL at least 6 independent clipping planes can be specified for the hardware pipeline.

A single OpenGL clip plane is defined by the plane equation

$ ax+by+cz+d = 0 $

When evaluating the above formula for points (x,y,z), results less or greater than zero indicate points on one or the other side of the plane.

For a plane with pivot point $\vec{p}$ and a normal $\vec{n}$ (pointing into the half space that is to be shown) the plane coefficients are:

The i-th OpenGL clip plane is specified via:

GLdouble equ[4];



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Page last modified on December 09, 2013, at 10:46 AM