Ensure that array passed to physics is always counter clockwise, fixes …

…#15361.

core/math/geometry.h

@@ -800,6 +800,21 @@ class Geometry {
  return Vector<Vector<Vector2> >();
  }
 
+ static bool is_polygon_clockwise(const Vector<Vector2> &p_polygon) {
+ int c = p_polygon.size();
+ if (c < 3)
+ return false;
+ const Vector2 *p = p_polygon.ptr();
+ real_t sum = 0;
+ for (int i = 0; i < c; i++) {
+ const Vector2 &v1 = p[i];
+ const Vector2 &v2 = p[(i + 1) % c];
+ sum += (v2.x - v1.x) * (v2.y + v1.y);
+ }
+
+ return sum > 0.0f;
+ }
+
  static PoolVector<PoolVector<Face3> > separate_objects(PoolVector<Face3> p_array);
 
  static PoolVector<Face3> wrap_geometry(PoolVector<Face3> p_array, real_t *p_error = NULL); ///< create a "wrap" that encloses the given geometry

scene/resources/convex_polygon_shape_2d.cpp

@@ -41,7 +41,11 @@ bool ConvexPolygonShape2D::_edit_is_selected_on_click(const Point2 &p_point, dou
 
 void ConvexPolygonShape2D::_update_shape() {
 
- Physics2DServer::get_singleton()->shape_set_data(get_rid(), points);
+ Vector<Vector2> final_points = points;
+ if (Geometry::is_polygon_clockwise(final_points)) { //needs to be counter clockwise
+ final_points.invert();
+ }
+ Physics2DServer::get_singleton()->shape_set_data(get_rid(), final_points);
  emit_changed();
 }
 
@@ -55,6 +59,7 @@ void ConvexPolygonShape2D::set_point_cloud(const Vector<Vector2> &p_points) {
 void ConvexPolygonShape2D::set_points(const Vector<Vector2> &p_points) {
 
  points = p_points;
+
  _update_shape();
 }