// Given point p, return point q on (or in) OBB b, closest to p
Vector2 ClosestPtPointOBB(Vector2 point, SimpleActor.OBB box)
{
Vector2 d = point - box._center;
// Start result at center of box; make steps from there
Vector2 closestOnBox = box._center;
// For each OBB axis...
for (int i = 0; i < 2; i++)
{
// ...project d onto that axis to get the distance
// along the axis of d from the box center
float dist = (Vector3.Project(d, box._local_axes[i])).magnitude;
// If distance farther than the box extents, clamp to the box
if (dist > box._extents[i])
{
dist = box._extents[i];
}
if (dist < -box._extents[i])
{
dist = -box._extents[i];
}
// Step that distance along the axis to get world coordinate
closestOnBox += dist * box._local_axes[i];
}
return(closestOnBox);
}
//Returns true if sphere s intersects OBB b, false otherwise.
//The point p on the OBB closest to the sphere center is also returned
bool TestCircleOBB(CircleObstacle obstacle, SimpleActor.OBB box, out Vector2 closestPoint)
{
// Find point p on OBB closest to sphere center
closestPoint = ClosestPtPointOBB(obstacle.Center, box);
// Sphere and OBB intersect if the (squared) distance from sphere
// center to point p is less than the (squared) sphere radius
Vector2 v = closestPoint - obstacle.Center;
return(v.sqrMagnitude <= obstacle.Radius * obstacle.Radius);
}