/// <summary> /// Ray-cast against the proxies in the tree. This relies on the callback /// to perform a exact ray-cast in the case were the proxy contains a Shape. /// The callback also performs the any collision filtering. This has performance /// roughly equal to k * log(n), where k is the number of collisions and n is the /// number of proxies in the tree. /// </summary> /// <param name="callback">A callback class that is called for each proxy that is hit by the ray.</param> /// <param name="input">The ray-cast input data. The ray extends from p1 to p1 + maxFraction * (p2 - p1).</param> public void RayCast(IRayCastCallback callback, ref RayCastInput input) { Vector2 p1 = input.Point1; Vector2 p2 = input.Point2; Vector2 r = p2 - p1; Debug.Assert(r.LengthSquared() > 0.0f); r.Normalize(); // v is perpendicular to the segment. Vector2 absV = MathUtils.Abs(new Vector2(-r.Y, r.X)); // Separating axis for segment (Gino, p80). // |dot(v, p1 - c)| > dot(|v|, h) float maxFraction = input.MaxFraction; // Build a bounding box for the segment. AABB segmentAABB = new AABB(); { Vector2 t = p1 + maxFraction * (p2 - p1); Vector2.Min(ref p1, ref t, out segmentAABB.LowerBound); Vector2.Max(ref p1, ref t, out segmentAABB.UpperBound); } _stack.Clear(); _stack.Push(_root); while (_stack.Count > 0) { int nodeId = _stack.Pop(); if (nodeId == NullNode) { continue; } DynamicTreeNode <T> node = _nodes[nodeId]; if (AABB.TestOverlap(ref node.AABB, ref segmentAABB) == false) { continue; } // Separating axis for segment (Gino, p80). // |dot(v, p1 - c)| > dot(|v|, h) Vector2 c = node.AABB.Center; Vector2 h = node.AABB.Extents; float separation = Math.Abs(Vector2.Dot(new Vector2(-r.Y, r.X), p1 - c)) - Vector2.Dot(absV, h); if (separation > 0.0f) { continue; } if (node.IsLeaf()) { RayCastInput subInput; subInput.Point1 = input.Point1; subInput.Point2 = input.Point2; subInput.MaxFraction = maxFraction; float value = callback.RayCastCallback(ref subInput, nodeId); if (value == 0.0f) { // the client has terminated the raycast. return; } if (value > 0.0f) { // Update segment bounding box. maxFraction = value; Vector2 t = p1 + maxFraction * (p2 - p1); segmentAABB.LowerBound = Vector2.Min(p1, t); segmentAABB.UpperBound = Vector2.Max(p1, t); } } else { _stack.Push(node.Child1); _stack.Push(node.Child2); } } }
public float RayCastCallback(ref RayCastInput input, Element <FixtureProxy> proxyId) { return(callback.RayCastCallback(ref input, proxyId.Value.ProxyId)); }