// Recursively remove all polygons in `polygons` that are inside this BSP
// tree.
public List <CSGPolygon> clipPolygons(List <CSGPolygon> polygons)
{
if (!validPlane)
{
return(new List <CSGPolygon>(polygons));
}
List <CSGPolygon> front = new List <CSGPolygon>();
List <CSGPolygon> back = new List <CSGPolygon>();
for (int i = 0; i < polygons.Count; i++)
{
plane.splitPolygon(polygons[i], front, back, front, back);
}
if (this.front != null)
{
front = this.front.clipPolygons(front);
}
if (this.back != null)
{
back = this.back.clipPolygons(back);
}
else
{
back = new List <CSGPolygon>();
}
front.AddRange(back);
return(front);
}
