https://bugs.freedesktop.org/show_bug.cgi?id=79504
--- Comment #5 from Kyle Blake kyle@klkblake.com --- Created attachment 100273 --> https://bugs.freedesktop.org/attachment.cgi?id=100273&action=edit testcase
Compile with gcc test.c -lGL -lglut. Depends on freeglut for context creation. Requires raycast.vert and raycast.frag to be in the working directory.