Clean up sphere intersection code a bit.

2 files changed, 7 insertions, 7 deletions

diff --git a/bench/libdimension/list.c b/bench/libdimension/list.c
index 9af3279..16eb501 100644
--- a/bench/libdimension/list.c
+++ b/bench/libdimension/list.c
@@ -103,7 +103,7 @@ main()
   sandglass_bench_noprecache(&sandglass, split = dmnsn_list_split(list));
   printf("dmnsn_list_split(): %ld\n", sandglass.grains);
 
-  /* dmnsn_list_sort() */ 
+  /* dmnsn_list_sort() */
   sandglass_bench(&sandglass, dmnsn_list_sort(list, &dmnsn_comparator));
   printf("dmnsn_list_sort(): %ld\n", sandglass.grains);
 
diff --git a/libdimension/sphere.c b/libdimension/sphere.c
index 0477c24..a3ecf2d 100644
--- a/libdimension/sphere.c
+++ b/libdimension/sphere.c
@@ -54,14 +54,14 @@ dmnsn_sphere_intersection_fn(const dmnsn_object *sphere, dmnsn_line line,
  
   /* Solve (x0 + nx*t)^2 + (y0 + ny*t)^2 + (z0 + nz*t)^2 == 1 */
   double a, b, c, t;
-  a = l.n.x*l.n.x + l.n.y*l.n.y + l.n.z*l.n.z;
-  b = 2.0*(l.n.x*l.x0.x + l.n.y*l.x0.y + l.n.z*l.x0.z);
-  c = l.x0.x*l.x0.x + l.x0.y*l.x0.y + l.x0.z*l.x0.z - 1.0;
+  a = dmnsn_vector_dot(l.n, l.n);
+  b = 2.0*dmnsn_vector_dot(l.n, l.x0);
+  c = dmnsn_vector_dot(l.x0, l.x0) - 1.0;
 
-  if (b*b - 4.0*a*c >= 0) {
-    t = (-b - sqrt(b*b - 4.0*a*c))/(2*a);
+  if (b*b - 4.0*a*c >= 0.0) {
+    t = (-b - sqrt(b*b - 4.0*a*c))/(2.0*a);
     if (t < 0.0) {
-      t = (-b + sqrt(b*b - 4.0*a*c))/(2*a);
+      t = (-b + sqrt(b*b - 4.0*a*c))/(2.0*a);
     }
 
     if (t >= 0.0) {