@brief Calculate the depth of the a given point within a sphere.
@param sphere the sphere to query.
@param x the X coordinate of the point.
@param y the Y coordinate of the point.
@param z the Z coordinate of the point.
@returns The depth of the point. Points inside the sphere will have a
positive depth, points outside it will have a negative depth, and points
on the surface will have a depth of zero.
@brief Calculate the depth of the a given point within a sphere.
@param sphere the sphere to query. @param x the X coordinate of the point. @param y the Y coordinate of the point. @param z the Z coordinate of the point.
@returns The depth of the point. Points inside the sphere will have a positive depth, points outside it will have a negative depth, and points on the surface will have a depth of zero.
@ingroup collide_sphere