cpBBSegmentQuery   xtlang

(bind-func cpBBSegmentQuery
  (lambda (bb:cpBB a:cpVect b:cpVect)
    (let ((delta (cpvsub b a)) (tmin (- 0. CPFLOAT_MAX)) (tmax CPFLOAT_MAX))
      (if (<> (tref delta 0) 0.)
        (let (
            (t1 (/ (- (tref bb 0) (tref a 0)) (tref delta 0)))
            (t2 (/ (- (tref bb 2) (tref a 0)) (tref delta 0))))
          (set! tmin (max tmin (min t1 t2)))
          (set! tmax (min tmax (max t1 t2)))))
      (if (<> (tref delta 1) 0.)
        (let (
            (t1 (/ (- (tref bb 1) (tref a 1)) (tref delta 1)))
            (t2 (/ (- (tref bb 3) (tref a 1)) (tref delta 1))))
          (set! tmin (max tmin (min t1 t2)))
          (set! tmax (min tmax (max t1 t2)))))
      (if (and (<= tmin tmax) (<= 0. tmax) (<= tmin 1.))
        (max tmin 0.)
        (CPFLOAT_MAX)))))