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Diffstat (limited to 'Box2d/Assets/Program/Box2d/Collision/Collision.CollideEdge.cs')
| -rw-r--r-- | Box2d/Assets/Program/Box2d/Collision/Collision.CollideEdge.cs | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/Box2d/Assets/Program/Box2d/Collision/Collision.CollideEdge.cs b/Box2d/Assets/Program/Box2d/Collision/Collision.CollideEdge.cs new file mode 100644 index 0000000..8ea3821 --- /dev/null +++ b/Box2d/Assets/Program/Box2d/Collision/Collision.CollideEdge.cs @@ -0,0 +1,100 @@ +/* + Box2DX Copyright (c) 2009 Ihar Kalasouski http://code.google.com/p/box2dx + Box2D original C++ version Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com + + This software is provided 'as-is', without any express or implied + warranty. In no event will the authors be held liable for any damages + arising from the use of this software. + + Permission is granted to anyone to use this software for any purpose, + including commercial applications, and to alter it and redistribute it + freely, subject to the following restrictions: + + 1. The origin of this software must not be misrepresented; you must not + claim that you wrote the original software. If you use this software + in a product, an acknowledgment in the product documentation would be + appreciated but is not required. + 2. Altered source versions must be plainly marked as such, and must not be + misrepresented as being the original software. + 3. This notice may not be removed or altered from any source distribution. +*/ + +using Box2DX.Common; + +namespace Box2DX.Collision +{ + public partial class Collision + { + // This implements 2-sided edge vs circle collision. + public static void CollideEdgeAndCircle(ref Manifold manifold, EdgeShape edge, XForm transformA, CircleShape circle, XForm transformB) + { + manifold.PointCount = 0; + Vec2 cLocal = Common.Math.MulT(transformA, Common.Math.Mul(transformB, circle._position)); + Vec2 normal = edge._normal; + Vec2 v1 = edge._v1; + Vec2 v2 = edge._v2; + float radius = edge._radius + circle._radius; + + // Barycentric coordinates + float u1 = Vec2.Dot(cLocal - v1, v2 - v1); + float u2 = Vec2.Dot(cLocal - v2, v1 - v2); + + if (u1 <= 0.0f) + { + // Behind v1 + if (Vec2.DistanceSquared(cLocal, v1) > radius * radius) + { + return; + } + + manifold.PointCount = 1; + manifold.Type = ManifoldType.FaceA; + manifold.LocalPlaneNormal = cLocal - v1; + manifold.LocalPlaneNormal.Normalize(); + manifold.LocalPoint = v1; + manifold.Points[0].LocalPoint = circle._position; + manifold.Points[0].ID.Key = 0; + } + else if (u2 <= 0.0f) + { + // Ahead of v2 + if (Vec2.DistanceSquared(cLocal, v2) > radius * radius) + { + return; + } + + manifold.PointCount = 1; + manifold.Type = ManifoldType.FaceA; + manifold.LocalPlaneNormal = cLocal - v2; + manifold.LocalPlaneNormal.Normalize(); + manifold.LocalPoint = v2; + manifold.Points[0].LocalPoint = circle._position; + manifold.Points[0].ID.Key = 0; + } + else + { + float separation = Vec2.Dot(cLocal - v1, normal); + if (separation < -radius || radius < separation) + { + return; + } + + manifold.PointCount = 1; + manifold.Type = ManifoldType.FaceA; + manifold.LocalPlaneNormal = separation < 0.0f ? -normal : normal; + manifold.LocalPoint = 0.5f * (v1 + v2); + manifold.Points[0].LocalPoint = circle._position; + manifold.Points[0].ID.Key = 0; + } + } + + // Polygon versus 2-sided edge. + public static void CollidePolyAndEdge(ref Manifold manifold, PolygonShape polygon, XForm transformA, EdgeShape edge, XForm transformB) + { + PolygonShape polygonB = new PolygonShape(); + polygonB.SetAsEdge(edge._v1, edge._v2); + + CollidePolygons(ref manifold, polygon, transformA, polygonB, transformB); + } + } +}
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