New dmnsn_intersection* type for ray-object intersections.

1 files changed, 63 insertions, 41 deletions

diff --git a/libdimension/objects.c b/libdimension/objects.c
index 32d3fdd..780c06b 100644
--- a/libdimension/objects.c
+++ b/libdimension/objects.c
@@ -27,8 +27,10 @@
  */
 
 /* Sphere object callbacks */
-static dmnsn_array *dmnsn_sphere_intersections_fn(const dmnsn_object *sphere,
-                                                  dmnsn_line line);
+
+static dmnsn_intersection *
+dmnsn_sphere_intersection_fn(const dmnsn_object *sphere, dmnsn_line line);
+
 static int dmnsn_sphere_inside_fn(const dmnsn_object *sphere,
                                   dmnsn_vector point);
 
@@ -38,18 +40,18 @@ dmnsn_new_sphere()
 {
   dmnsn_object *sphere = dmnsn_new_object();
   if (sphere) {
-    sphere->intersections_fn = &dmnsn_sphere_intersections_fn;
-    sphere->inside_fn        = &dmnsn_sphere_inside_fn;
+    sphere->intersection_fn = &dmnsn_sphere_intersection_fn;
+    sphere->inside_fn       = &dmnsn_sphere_inside_fn;
   }
   return sphere;
 }
 
-/* Return a list of insersections of `line' with a sphere */
-static dmnsn_array *
-dmnsn_sphere_intersections_fn(const dmnsn_object *sphere, dmnsn_line line)
+/* Returns the closest intersection of `line' with `sphere' */
+static dmnsn_intersection *
+dmnsn_sphere_intersection_fn(const dmnsn_object *sphere, dmnsn_line line)
 {
-  double a, b, c, t[2];
-  dmnsn_array *array = dmnsn_new_array(sizeof(double));
+  double a, b, c, t;
+  dmnsn_intersection *intersection = NULL;
 
   /* Solve (x0 + nx*t)^2 + (y0 + ny*t)^2 + (z0 + nz*t)^2 == 1 */
 
@@ -58,13 +60,20 @@ dmnsn_sphere_intersections_fn(const dmnsn_object *sphere, dmnsn_line line)
   c = line.x0.x*line.x0.x + line.x0.y*line.x0.y + line.x0.z*line.x0.z - 1.0;
 
   if (b*b - 4.0*a*c >= 0) {
-    t[0] = (-b + sqrt(b*b - 4.0*a*c))/(2*a);
-    t[1] = (-b - sqrt(b*b - 4.0*a*c))/(2*a);
-    dmnsn_array_set(array, 0, &t[0]);
-    dmnsn_array_set(array, 1, &t[1]);
+    t = (-b - sqrt(b*b - 4.0*a*c))/(2*a);
+    if (t < 0.0) {
+      t = (-b + sqrt(b*b - 4.0*a*c))/(2*a);
+    }
+
+    if (t >= 0.0) {
+      intersection = dmnsn_new_intersection();
+      intersection->ray     = line;
+      intersection->t       = t;
+      intersection->texture = sphere->texture;
+    }
   }
 
-  return array;
+  return intersection;
 }
 
 /* Return whether a point is inside a sphere (x**2 + y**2 + z**2 < 1.0) */
@@ -79,8 +88,8 @@ dmnsn_sphere_inside_fn(const dmnsn_object *sphere, dmnsn_vector point)
  */
 
 /* Cube callbacks */
-static dmnsn_array *dmnsn_cube_intersections_fn(const dmnsn_object *cube,
-                                                  dmnsn_line line);
+static dmnsn_intersection *dmnsn_cube_intersection_fn(const dmnsn_object *cube,
+                                                      dmnsn_line line);
 static int dmnsn_cube_inside_fn(const dmnsn_object *cube,
                                   dmnsn_vector point);
 
@@ -90,71 +99,84 @@ dmnsn_new_cube()
 {
   dmnsn_object *cube = dmnsn_new_object();
   if (cube) {
-    cube->intersections_fn = &dmnsn_cube_intersections_fn;
+    cube->intersection_fn = &dmnsn_cube_intersection_fn;
     cube->inside_fn        = &dmnsn_cube_inside_fn;
   }
   return cube;
 }
 
 /* Intersections callback for a cube */
-static dmnsn_array *
-dmnsn_cube_intersections_fn(const dmnsn_object *cube, dmnsn_line line)
+static dmnsn_intersection *
+dmnsn_cube_intersection_fn(const dmnsn_object *cube, dmnsn_line line)
 {
-  double t;
+  double t = -1.0, t_temp;
   dmnsn_vector p;
-  dmnsn_array *array = dmnsn_new_array(sizeof(double));
+  dmnsn_intersection *intersection = NULL;
 
   /* Six ray-plane intersection tests (x, y, z) = +/- 1.0 */
 
   if (line.n.x != 0.0) {
     /* x = -1.0 */
-    t = (-1.0 - line.x0.x)/line.n.x;
-    p = dmnsn_line_point(line, t);
-    if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0) {
-      dmnsn_array_push(array, &t);
+    t_temp = (-1.0 - line.x0.x)/line.n.x;
+    p = dmnsn_line_point(line, t_temp);
+    if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0
+        && t_temp >= 0.0 && (t < 0.0 || t_temp < t)) {
+      t = t_temp;
     }
 
     /* x = 1.0 */
-    t = (1.0 - line.x0.x)/line.n.x;
+    t_temp = (1.0 - line.x0.x)/line.n.x;
     p = dmnsn_line_point(line, t);
-    if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0) {
-      dmnsn_array_push(array, &t);
+    if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0
+        && t_temp >= 0.0 && (t < 0.0 || t_temp < t)) {
+      t = t_temp;
     }
   }
 
   if (line.n.y != 0.0) {
     /* y = -1.0 */
-    t = (-1.0 - line.x0.y)/line.n.y;
+    t_temp = (-1.0 - line.x0.y)/line.n.y;
     p = dmnsn_line_point(line, t);
-    if (p.x >= -1.0 && p.x <= 1.0 && p.z >= -1.0 && p.z <= 1.0) {
-      dmnsn_array_push(array, &t);
+    if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0
+        && t_temp >= 0.0 && (t < 0.0 || t_temp < t)) {
+      t = t_temp;
     }
 
     /* y = 1.0 */
-    t = (1.0 - line.x0.y)/line.n.y;
+    t_temp = (1.0 - line.x0.y)/line.n.y;
     p = dmnsn_line_point(line, t);
-    if (p.x >= -1.0 && p.x <= 1.0 && p.z >= -1.0 && p.z <= 1.0) {
-      dmnsn_array_push(array, &t);
+    if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0
+        && t_temp >= 0.0 && (t < 0.0 || t_temp < t)) {
+      t = t_temp;
     }
   }
 
   if (line.n.z != 0.0) {
     /* z = -1.0 */
-    t = (-1.0 - line.x0.z)/line.n.z;
+    t_temp = (-1.0 - line.x0.z)/line.n.z;
     p = dmnsn_line_point(line, t);
-    if (p.x >= -1.0 && p.x <= 1.0 && p.y >= -1.0 && p.y <= 1.0) {
-      dmnsn_array_push(array, &t);
+    if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0
+        && t_temp >= 0.0 && (t < 0.0 || t_temp < t)) {
+      t = t_temp;
     }
 
     /* z = 1.0 */
-    t = (1.0 - line.x0.z)/line.n.z;
+    t_temp = (1.0 - line.x0.z)/line.n.z;
     p = dmnsn_line_point(line, t);
-    if (p.x >= -1.0 && p.x <= 1.0 && p.y >= -1.0 && p.y <= 1.0) {
-      dmnsn_array_push(array, &t);
+    if (p.y >= -1.0 && p.y <= 1.0 && p.z >= -1.0 && p.z <= 1.0
+        && t_temp >= 0.0 && (t < 0.0 || t_temp < t)) {
+      t = t_temp;
     }
   }
 
-  return array;
+  if (t >= 0.0) {
+    intersection = dmnsn_new_intersection();
+    intersection->ray     = line;
+    intersection->t       = t;
+    intersection->texture = cube->texture;
+  }
+
+  return intersection;
 }
 
 /* Inside callback for a cube */