CSCI 480/580 Lecture 24 - In-Class Problems

Let's suppose, without loss of generality, that we're looking to clip a triangle against the $x = 1$ plane. We can develop a solution for this and generalize it to handle the other five clipping planes.

We saw that there are 4 cases we need to handle:

1. all in (keep the triangle)
2. all out (discard the triangle)
3. one in, two out (create one clipped triangle)
4. two in, one out (create two clipped triangles)

Case 4 is illustrated here:

1. Given three vertices $\mathbf{a}, \mathbf{b}, \mathbf{c}$, write pseudocode to decide which of the above cases applies to a given triangle when clipping against the $x = 1$ plane.
2. Write pseudocode to produce the vertices of $\mathbf{a}', \mathbf{b}', \mathbf{c}'$ of the new triangle resulting from the case 2 ("one in, two out").
3. Write pseudocode to produce the vertices $\mathbf{a}_1, \mathbf{b}_1, \mathbf{c}_1$ and $\mathbf{a}_2, \mathbf{b}_2, \mathbf{c}_2$ of the two new triangles resulting from the case 4 ("one in, two out").