// all of the contacts where second's edges intersect first's body
// handles all cordinate transformation from each body to the world
private IEnumerable <Contact> ContactsOnFirst(IBody first, IBody second)
{
IEdgeIntersector firstShape = first.CollisionShape;
IEdgeIntersector secondShape = second.CollisionShape;
Transform firstTransform = first.Dynamics.Transform;
Transform secondTransform = second.Dynamics.Transform;
var secondToFirst = new Transformation(secondTransform, firstTransform);
if (IntersectStrats.HasStrategy(firstShape, secondShape))
{
return(IntersectStrats.EnactStrategy(firstShape, secondShape, secondToFirst.Reverse()).Select(i => new Contact(i, first, second)));
}
// general case
return
// everything is converted to the firsts local transform coords
(secondShape.Edges.SelectMany(secondEdge => firstShape.FindIntersections(secondToFirst.TransformEdge(secondEdge))
.Select(i => new Contact(firstTransform.ToWorldSpace(i), first, second)))); // then to world coords
}
