If you only want to view a section of the geometry, you must define two clipping planes. One at the beginning of the section and one at the end of the section. In the following `start`

and `to`

defines the range of the section. `start`

must be smaller than `end`

:

```
double[] Elevyz_start = new double[] { 1, 0, 0, -start };
double[] Elevyz_end = new double[] { -1, 0, 0, end };
GL.ClipPlane(ClipPlaneName.ClipPlane2, Elevyz_end);
GL.Enable(EnableCap.ClipPlane2);
GL.ClipPlane(ClipPlaneName.ClipPlane5, Elevyz_start);
GL.Enable(EnableCap.ClipPlane5);
```

The maximum number of clipping planes is guaranteed to be at least 6. See `GL_MAX_CLIP_PLANES`

respectively `glClipPlane`

.

The parameters to the clipping plane are interpreted as a Plane Equation.
The first 3 components of the plane equation are the normal vector to the clipping plane. The 4th component is the distance to the origin. Hence the sign of the distance depends on the direction on the normal vector. Therefore, `start`

is inverted when setting up the plane equation.

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