I'm new to libGDX and from what I can tell the Intersector class has overlap methods for Rectangle/Rectangle, Circle/Circle, Circle/Rectangle, and Polygon/Polygon, but for some reason it doesn't seem to have any methods for checking Polygon/Rectangle or Polygon/Circle.
Is there a recommended way to check for collision between polygon and rect/circle?
Also, is there some reason why this has been left out of the Intersector class? (ie, should I avoid it? If so, what's the recommended alternative?)
The best way to handle those collisions would be to use a physics engine like Box2D which already comes packed with Libgdx. When a collision occurs in Box2D a event gets fired and you can easly handle that event. So you should probably take a look here.
Of course there are other ways of dealing of dealing with collision detection. With a little bit of maths you could probaly figure out just what you need on your own, also Box2D comes with alot of other features that will benefit you.
The solution I've used to implement these checks without Box2D is as follows..
Check for collisions between Polygon and Rectangle:
// Check if Polygon intersects Rectangle private boolean isCollision(Polygon p, Rectangle r) { Polygon rPoly = new Polygon(new float[] { 0, 0, r.width, 0, r.width, r.height, 0, r.height }); rPoly.setPosition(r.x, r.y); if (Intersector.overlapConvexPolygons(rPoly, p)) return true; return false; }
Check for collisions between Polygon and Circle:
// Check if Polygon intersects Circle private boolean isCollision(Polygon p, Circle c) { float[] vertices = p.getTransformedVertices(); Vector2 center = new Vector2(c.x, c.y); float squareRadius = c.radius * c.radius; for (int i = 0; i < vertices.length; i += 2) { if (i == 0) { if (Intersector.intersectSegmentCircle(new Vector2( vertices[vertices.length - 2], vertices[vertices.length - 1]), new Vector2( vertices[i], vertices[i + 1]), center, squareRadius)) return true; } else { if (Intersector.intersectSegmentCircle(new Vector2( vertices[i - 2], vertices[i - 1]), new Vector2( vertices[i], vertices[i + 1]), center, squareRadius)) return true; } } return false; }
The Poly/Circle check illustrated here was written by Cristiano Santos in this thread and the Poly/Rect check is a quick homebrew solution I came up with.
