Line–sphere intersection
1. no intersection
2. single-point intersection
3. two-point intersection
In analytic geometry, a line and a sphere can intersect in three ways:
- no intersection at all,
- intersection at exactly one point, and
- intersection at two points.
Methods for distinguishing these cases, and determining the coordinates for the points in the latter cases, are useful in a number of circumstances. For example, it is a common calculation to perform during ray tracing.