/// <summary>
/// Computes an intersection of the ray and the sphere
/// </summary>
public static bool RaySphere(Vector3 rayOrigin, Vector3 rayDirection, Vector3 sphereCenter, float sphereRadius,
out IntersectionRaySphere intersection)
{
Vector3 originToCenter = sphereCenter - rayOrigin;
float centerProjection = Vector3.Dot(rayDirection, originToCenter);
if (centerProjection + sphereRadius < -Geometry.Epsilon)
{
intersection = IntersectionRaySphere.None();
return(false);
}
float sqrDistanceToLine = originToCenter.sqrMagnitude - centerProjection * centerProjection;
float sqrDistanceToIntersection = sphereRadius * sphereRadius - sqrDistanceToLine;
if (sqrDistanceToIntersection < -Geometry.Epsilon)
{
intersection = IntersectionRaySphere.None();
return(false);
}
if (sqrDistanceToIntersection < Geometry.Epsilon)
{
if (centerProjection < -Geometry.Epsilon)
{
intersection = IntersectionRaySphere.None();
return(false);
}
intersection = IntersectionRaySphere.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 = IntersectionRaySphere.None();
return(false);
}
intersection = IntersectionRaySphere.Point(rayOrigin + rayDirection * distanceB);
return(true);
}
Vector3 pointA = rayOrigin + rayDirection * distanceA;
Vector3 pointB = rayOrigin + rayDirection * distanceB;
intersection = IntersectionRaySphere.TwoPoints(pointA, pointB);
return(true);
}
/// <summary>
/// Computes an intersection of the ray and the sphere
/// </summary>
public static bool RaySphere(Ray ray, Sphere sphere, out IntersectionRaySphere intersection)
{
return(RaySphere(ray.origin, ray.direction, sphere.center, sphere.radius, out intersection));
}