public static bool CircleToPolygon(Circle circle, Polygon polygon, out CollisionResult result)
{
result = new CollisionResult();
// circle position in the polygons coordinates
var poly2Circle = circle.position - polygon.position;
// first, we need to find the closest distance from the circle to the polygon
float distanceSquared;
var closestPoint = Polygon.GetClosestPointOnPolygonToPoint(polygon.Points, poly2Circle, out distanceSquared,
out result.Normal);
// make sure the squared distance is less than our radius squared else we are not colliding. Note that if the Circle is fully
// contained in the Polygon the distance could be larger than the radius. Because of that we also make sure the circle position
// is not inside the poly.
var circleCenterInsidePoly = polygon.ContainsPoint(circle.position);
if (distanceSquared > circle.Radius * circle.Radius && !circleCenterInsidePoly)
{
return(false);
}
// figure out the mtv. We have to be careful to deal with circles fully contained in the polygon or with their center contained.
Vector2 mtv;
if (circleCenterInsidePoly)
{
mtv = result.Normal * (Mathf.Sqrt(distanceSquared) - circle.Radius);
}
else
{
// if we have no distance that means the circle center is on the polygon edge. Move it only by its radius
if (distanceSquared == 0)
{
mtv = result.Normal * circle.Radius;
}
else
{
var distance = Mathf.Sqrt(distanceSquared);
mtv = -(poly2Circle - closestPoint) * ((circle.Radius - distance) / distance);
}
}
result.MinimumTranslationVector = mtv;
result.Point = closestPoint + polygon.position;
return(true);
}
public static bool PointToPoly(Vector2 point, Polygon poly, out CollisionResult result)
{
result = new CollisionResult();
if (poly.ContainsPoint(point))
{
float distanceSquared;
var closestPoint = Polygon.GetClosestPointOnPolygonToPoint(poly.Points, point - poly.position, out distanceSquared, out result.Normal);
result.MinimumTranslationVector = result.Normal * Mathf.Sqrt(distanceSquared);
result.Point = closestPoint + poly.position;
return(true);
}
return(false);
}
