Question

I have a capsule defined by two points A and B and radius r. The ray is defined by equation: X = O + D*t. Now I need to get t for all (0-2) intersection points.

One possible solution would be to calculate intersection with spheres at A and B and intersections with cylinder. Then because capsule is convex I would just take minimum and maximum of all resulting t values.

But as wikipedia states, capsule intersection test should be even simpler than cylinder intersection test. Could somebody point me to an efficient capsule-ray intersection algorithm?

Answer 1

To test whether a capsule intersects a ray line just test distance between the line segment crossing points A and B and the ray line. If the distance is smaller than radius r then there are two intersecting points, if is equal there is one touching point.

To calculate intersection do as you described.