I want to clip triangles to the near plane, in homogeneous clip space, so for each edge, I have to see if it crossed the near plane. If it has, I linearly interpolate the two endpoints based on the intersection point.

The problem is that this works well in view space, because we only have to compare the vertices' $z$ against the near plane. But in homogeneous clip space, $z$ goes from $-w$ to $w$, and this $w$ is different for each point! So how can I perform the clipping in homogeneous clip space, and then interpolate the attributes based on the intersection point, if the two endpoints don't have the same near plane ($w$ are different)?

  • $\begingroup$ You use the exact same math, except in 4 dimensions instead of 3. $\endgroup$ – Nicol Bolas Aug 9 at 16:25

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