evanw / polyfrag

Geometry library that splits polyhedra using 3D planes

This library contains a stable algorithm for splitting a convex polyhedron into two pieces on either side of a 3D plane. It is useful for generating polyhedron fragments to make a polyhedron look like it's breaking apart.

Example usage:

srand(1);
std::vector<Polyhedron *> polyhedra;
Polyhedron::recursiveSlice(Polyhedron::box(Vector3D(-0.5, -2, -0.5), Vector3D(0.5, 2, 0.5)), polyhedra, 4);

for (int i = 0; i < polyhedra.size(); i++)
{
    Vector3D offset = polyhedra[i]->getCentroid() * 0.5;
    glPushMatrix();
    glTranslatef(offset.x, offset.y, offset.z);
    polyhedra[i]->draw();
    glPopMatrix();
    delete polyhedra[i];
}

The generated mesh for a polyhedron uses a shared set of vertices which each polygon indexes into. All polygons are generated in counterclockwise order.