aabbRaycast function Physics

RayShapeHit? aabbRaycast(Ray ray, Aabb3 box, double maxDistance)

Raycast against an axis-aligned box, the conservative fallback used by sphere casts against inflated collider bounds.

Implementation

RayShapeHit? aabbRaycast(Ray ray, Aabb3 box, double maxDistance) {
  final dir = ray.direction.normalized();
  var tmin = -double.infinity;
  var tmax = double.infinity;
  var hitAxis = -1;
  var hitSign = 1.0;
  for (var axis = 0; axis < 3; axis++) {
    final o = ray.origin[axis];
    final d = dir[axis];
    final lo = box.min[axis];
    final hi = box.max[axis];
    if (d.abs() < 1e-9) {
      if (o < lo || o > hi) return null;
      continue;
    }
    var t1 = (lo - o) / d;
    var t2 = (hi - o) / d;
    var nearSign = -1.0;
    if (t1 > t2) {
      final tmp = t1;
      t1 = t2;
      t2 = tmp;
      nearSign = 1.0;
    }
    if (t1 > tmin) {
      tmin = t1;
      hitAxis = axis;
      hitSign = nearSign;
    }
    if (t2 < tmax) tmax = t2;
    if (tmin > tmax || tmax < 0) return null;
  }
  final t = tmin >= 0 ? tmin : tmax;
  if (t < 0 || t > maxDistance) return null;
  final hitPoint = ray.origin + dir.scaled(t);
  final normal = Vector3.zero();
  if (hitAxis >= 0) normal[hitAxis] = hitSign;
  return RayShapeHit(t, hitPoint, normal);
}