More on bilinear patch intersection

Because ray - BL patch involve solving a quadratic, I am concerned there will be "cracking" issues where rays sneak between adjacent patches. A cure for that would be to do four "ordered edge" tests on the ray and the patch edges. More information on such tests in in Andrew Kensler's and my recent triangle intersection paper. Note that Pluecker coordinates are not needed-- the easier to comprehend (for me) triple product test will do the job.