collideCircles method

void collideCircles(Manifold manifold, CircleShape circle1, Transform xfA, CircleShape circle2, Transform xfB,)

Compute the collision manifold between two circles.

Implementation

void collideCircles(
  Manifold manifold,
  CircleShape circle1,
  Transform xfA,
  CircleShape circle2,
  Transform xfB,
) {
  manifold.pointCount = 0;

  // after inline:
  final circle1p = circle1.position;
  final circle2p = circle2.position;
  final pAx = (xfA.q.cos * circle1p.x - xfA.q.sin * circle1p.y) + xfA.p.x;
  final pAy = (xfA.q.sin * circle1p.x + xfA.q.cos * circle1p.y) + xfA.p.y;
  final pBx = (xfB.q.cos * circle2p.x - xfB.q.sin * circle2p.y) + xfB.p.x;
  final pBy = (xfB.q.sin * circle2p.x + xfB.q.cos * circle2p.y) + xfB.p.y;
  final dx = pBx - pAx;
  final dy = pBy - pAy;
  final distSqr = dx * dx + dy * dy;
  // end inline

  final radius = circle1.radius + circle2.radius;
  if (distSqr > radius * radius) {
    return;
  }

  manifold.type = ManifoldType.circles;
  manifold.localPoint.setFrom(circle1p);
  manifold.localNormal.setZero();
  manifold.pointCount = 1;

  manifold.points[0].localPoint.setFrom(circle2p);
  manifold.points[0].id.zero();
}