/**
* Takes all point vectors ("vertexes") of the polygon describing the face and sorts them
* in clockwise order.
*/
public function sortVerticesClockwise()
{
$center = $this->calculateCenter();
for ($n = 0; $n <= count($this->vertexes) - 3; $n++) {
$a = new \Math_Vector3(\Math_VectorOp::substract($this->vertexes[$n], $center)->getTuple());
$a->normalize();
$p = Plane::getInstanceByThreePositionVectors($this->vertexes[$n], $center, new \Math_Vector3(\Math_VectorOp::add($center, $this->plane->getNormalVectorNormalized())->getTuple()));
$smallestAngle = -1;
$smallest = -1;
for ($m = $n + 1; $m <= count($this->vertexes) - 1; $m++) {
if ($p->calculateSideOfPointVector($this->vertexes[$m]) !== Plane::SIDE_BACK) {
$b = new \Math_Vector3(\Math_VectorOp::substract($this->vertexes[$m], $center)->getTuple());
$b->normalize();
$angle = \Math_VectorOp::dotProduct($a, $b);
if ($angle > $smallestAngle) {
$smallestAngle = $angle;
$smallest = $m;
}
}
}
if ($smallest == -1) {
throw new \RuntimeException('Error: Degenerate polygon!');
}
//swap vertices
$temp = $this->vertexes[$n + 1];
$this->vertexes[$n + 1] = $this->vertexes[$smallest];
$this->vertexes[$smallest] = $temp;
unset($temp);
}
// Check if vertex order needs to be reversed for back-facing polygon
$newPlane = Plane::getInstanceByThreePositionVectors($this->vertexes[0], $this->vertexes[1], $this->vertexes[2]);
if (\Math_VectorOp::dotProduct($newPlane->getNormalVectorNormalized(), $this->plane->getNormalVectorNormalized()) < 0) {
array_reverse($this->vertexes);
}
}
