/// <summary>
/// Determines if the ray intersects with the given sphere.
/// </summary>
/// <param name="sphere">Sphere to check intersection with</param>
/// <returns></returns>
public bool IntersectsWith(FSphere sphere, out float intersectionDist)
{
// From http://gamedev.stackexchange.com/questions/96459/fast-ray-sphere-collision-code
// This is the ray origin's offset from the center of the sphere.
Vector3 offsetFromSphereCenter = Origin - sphere.Center;
float radiusSquared = sphere.Radius * sphere.Radius;
float offsetDotRadiusSquared = Vector3.Dot(offsetFromSphereCenter, Direction);
// If either of these are true, that means the sphere is behind or surrounding the starting point.
// Basically, the sphere is behind the ray's origin, or the ray's origin is within the sphere
if (offsetDotRadiusSquared < 0 || Vector3.Dot(offsetFromSphereCenter, offsetFromSphereCenter) < radiusSquared)
{
intersectionDist = float.MaxValue;
return(false);
}
// Flatten the ray offset onto the plan passing through the sphere's center perpendicular to the ray.
// This gives the closest approach of the ray to the center of the sphere.
Vector3 flattening = offsetFromSphereCenter - offsetDotRadiusSquared * Direction;
float flatteningSquared = Vector3.Dot(flattening, flattening);
// If this is true, the closest approach of the ray to the sphere is outside the sphere.
// Basically, the ray doesn't intersect the sphere.
if (flatteningSquared > radiusSquared)
{
intersectionDist = float.MaxValue;
return(false);
}
// This is the distance from the plane where the ray enters and exits the sphere.
float distanceFromPlane = (float)Math.Sqrt(radiusSquared - flatteningSquared);
// This is the intersection point relative to the sphere center.
Vector3 intersection = flattening - distanceFromPlane * Direction;
Vector3 dirToIntersection = sphere.Center + intersection;
dirToIntersection.Normalize();
intersectionDist = (Origin - intersection).Length;
return(true);
}
/// <summary>
/// Determines if the ray intersects with the given sphere.
/// </summary>
/// <param name="sphere">Sphere to check intersection with</param>
/// <returns></returns>
public bool IntersectsWith(FSphere sphere, out float intersectionDist)
{
// From http://gamedev.stackexchange.com/questions/96459/fast-ray-sphere-collision-code
// This is the ray origin's offset from the center of the sphere.
Vector3 offsetFromSphereCenter = Origin - sphere.Center;
float radiusSquared = sphere.Radius * sphere.Radius;
float offsetDotRadiusSquared = Vector3.Dot(offsetFromSphereCenter, Direction);
// If either of these are true, that means the sphere is behind or surrounding the starting point.
// Basically, the sphere is behind the ray's origin, or the ray's origin is within the sphere
if (offsetDotRadiusSquared < 0 || Vector3.Dot(offsetFromSphereCenter, offsetFromSphereCenter) < radiusSquared)
{
intersectionDist = float.MaxValue;
return false;
}
// Flatten the ray offset onto the plan passing through the sphere's center perpendicular to the ray.
// This gives the closest approach of the ray to the center of the sphere.
Vector3 flattening = offsetFromSphereCenter - offsetDotRadiusSquared * Direction;
float flatteningSquared = Vector3.Dot(flattening, flattening);
// If this is true, the closest approach of the ray to the sphere is outside the sphere.
// Basically, the ray doesn't intersect the sphere.
if (flatteningSquared > radiusSquared)
{
intersectionDist = float.MaxValue;
return false;
}
// This is the distance from the plane where the ray enters and exits the sphere.
float distanceFromPlane = (float)Math.Sqrt(radiusSquared - flatteningSquared);
// This is the intersection point relative to the sphere center.
Vector3 intersection = flattening - distanceFromPlane * Direction;
Vector3 dirToIntersection = sphere.Center + intersection;
dirToIntersection.Normalize();
intersectionDist = (Origin - intersection).Length;
return true;
}
