fmod -> mod (R6RS handles floating point modulo)

math.ss

@@ -10,11 +10,6 @@
 
 (define (sqr x) (* x x))
 
-(define (fmod n modulus)
-  (if (negative? n)
-      (do ([n n (+ n modulus)]) ((positive? n) n))
-      (do ([n n (- n modulus)]) ((negative? n) (+ n modulus)))))
-
 (define (clamp x xmin xmax)
   (max xmin (min x xmax)))
 
@@ -171,13 +166,13 @@
   (- (step edge0 x) (step edge1 x)))
 
 (define (pulsetrain edge period x)
-  (pulse edge period (fmod x period)))
+  (pulse edge period (mod x period)))
 
 (define (smoothpulse e0 e1 e2 e3 x)
   (- (smoothstep e0 e1 x) (smoothstep e2 e3 x)))
 
 (define (smoothpulsetrain e0 e1 e2 e3 period x)
-  (smoothpulse e0 e1 e2 e3 (fmod x period)))
+  (smoothpulse e0 e1 e2 e3 (mod x period)))
 
 (define (fadeout g g-avg featuresize fwidth)
   (mix-num g g-avg (smoothstep .2 .6 (/ fwidth featuresize))))

objects.ss

@@ -171,7 +171,7 @@
    0.5))
 
 (define (plane-point->texture object point)
-  (make-vec (fmod (vec-i point) 1) (fmod (vec-j point) 1) 0))
+  (make-vec (mod (vec-i point) 1) (mod (vec-j point) 1) 0))
 
 (define (polyhedron-intersections obj ray)
   (let ([origin (<ray> origin ray)]

user-shaders.ss

@@ -45,7 +45,7 @@
   (let ([pnt (point->surface object intersect-point)]
         [Nf (faceforward (vec-normalize normal) incoming)])
     (let* ([t (vec-j pnt)]
-           [tmod (fmod (* t frequency) 1)])
+           [tmod (mod (* t frequency) 1)])
       (color-mul Os
         (if (< tmod .5)
             Cs
@@ -57,9 +57,9 @@
 (define-shader checker ([Kd 1] [Ka .5] [frequency 4] [blackcolor black])
   (let ([pnt (point->surface object intersect-point)]
         [Nf (faceforward (vec-normalize normal) incoming)])
-    (let ([xmod (fmod (* (vec-i pnt) frequency) (+ 1 EPSILON))]
-          [ymod (fmod (* (vec-j pnt) frequency) (+ 1 EPSILON))]
-          [zmod (fmod (* (vec-k pnt) frequency) (+ 1 EPSILON))])
+    (let ([xmod (mod (* (vec-i pnt) frequency) (+ 1 EPSILON))]
+          [ymod (mod (* (vec-j pnt) frequency) (+ 1 EPSILON))]
+          [zmod (mod (* (vec-k pnt) frequency) (+ 1 EPSILON))])
       (color-mul Os
         (if (< zmod .5)
             (if (< xmod .5)
@@ -249,8 +249,8 @@
   ([Ka 1] [Kd .75] [Ks .4] [roughness .1] [specularcolor white]
    [density .25] [frequency 20])
   (let ([st (point->texture object (point->surface object intersect-point))])
-    (if (or (< (fmod (* (vec-i st) frequency) 1) density)
-            (< (fmod (* (vec-j st) frequency) 1) density))
+    (if (or (< (mod (* (vec-i st) frequency) 1) density)
+            (< (mod (* (vec-j st) frequency) 1) density))
         (let ([Nf (faceforward (vec-normalize normal) incoming)]
               [V  (vec-normalize (vec-reverse incoming))])
           (values