How to use bounding sphere intersects ? about directxtk HOT 1 CLOSED

All that is required is that both the bounding volume and the ray are in the same space, but it could go either way. You can transform the ray into the model's space to do the test, or you can transform the sphere into the world (or view) space to do the test.

You transform a sphere by transforming it's center and then scaling the radius by any scale factor, which is what the BoundingSphere::Transform method does.

You can transform the ray by transforming it's starting point and then transforming the normal (which you use a different version of the transform function that ignores the translation offset).

from directxtk.