/// <summary>
/// Computes an intersection of the ray and the circle
/// </summary>
public static bool RayCircle(Vector2 rayOrigin, Vector2 rayDirection, Vector2 circleCenter, float circleRadius,
out IntersectionRayCircle intersection)
{
Vector2 originToCenter = circleCenter - rayOrigin;
float centerProjection = Vector2.Dot(rayDirection, originToCenter);
if (centerProjection + circleRadius < -Geometry.Epsilon)
{
intersection = IntersectionRayCircle.None();
return(false);
}
float sqrDistanceToLine = originToCenter.sqrMagnitude - centerProjection * centerProjection;
float sqrDistanceToIntersection = circleRadius * circleRadius - sqrDistanceToLine;
if (sqrDistanceToIntersection < -Geometry.Epsilon)
{
intersection = IntersectionRayCircle.None();
return(false);
}
if (sqrDistanceToIntersection < Geometry.Epsilon)
{
if (centerProjection < -Geometry.Epsilon)
{
intersection = IntersectionRayCircle.None();
return(false);
}
intersection = IntersectionRayCircle.Point(rayOrigin + rayDirection * centerProjection);
return(true);
}
// Line intersection
float distanceToIntersection = Mathf.Sqrt(sqrDistanceToIntersection);
float distanceA = centerProjection - distanceToIntersection;
float distanceB = centerProjection + distanceToIntersection;
if (distanceA < -Geometry.Epsilon)
{
if (distanceB < -Geometry.Epsilon)
{
intersection = IntersectionRayCircle.None();
return(false);
}
intersection = IntersectionRayCircle.Point(rayOrigin + rayDirection * distanceB);
return(true);
}
Vector2 pointA = rayOrigin + rayDirection * distanceA;
Vector2 pointB = rayOrigin + rayDirection * distanceB;
intersection = IntersectionRayCircle.TwoPoints(pointA, pointB);
return(true);
}
/// <summary>
/// Computes an intersection of the ray and the circle
/// </summary>
public static bool RayCircle(Ray2D ray, Circle2 circle, out IntersectionRayCircle intersection)
{
return(RayCircle(ray.origin, ray.direction, circle.center, circle.radius, out intersection));
}
