Simplify the Hittable API

We need to disable strict aliasing, but it is weird anyways:
https://blog.regehr.org/archives/1307

build.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 CC=${CC:-"gcc"}
-CFLAGS=${CFLAGS:-"-Wall -Wextra -std=gnu18 -g -fsanitize=address"}
+CFLAGS=${CFLAGS:-"-Wall -Wextra -std=gnu18 -fno-strict-aliasing -g"}
 LDFLAGS=${LDFLAGS:-"-lm"}
 MAIN_FILE=${MAIN_FILE:-"main.c"}
 

hittable.c

@@ -15,25 +15,22 @@ bool hittable_hit(const Hittable *hittable, Ray r, double t_min, double t_max,
                   HitRecord *record) {
   switch (hittable->type) {
   case HITTABLE_LIST:
-    return hittable_list_hit(hittable->data, r, t_min, t_max, record);
+    return hittable_list_hit((const HittableList *)hittable, r, t_min, t_max,
+                             record);
   case HITTABLE_SPHERE:
-    return sphere_hit(hittable->data, r, t_min, t_max, record);
+    return sphere_hit((const Sphere *)hittable, r, t_min, t_max, record);
   }
   return false;
 }
 
-Hittable make_hittable_list(const HittableList *list) {
-  return (Hittable){.type = HITTABLE_LIST, .data = list};
-}
-
 static void hittable_list_grow(HittableList *list, size_t n) {
   if (list->objects) {
-    list->objects = realloc(list->objects, n);
+    list->objects = realloc(list->objects, n * sizeof(Hittable *));
     if (!list->objects)
       abort();
     list->capacity = n;
   } else {
-    list->objects = malloc(n * sizeof(Hittable));
+    list->objects = malloc(n * sizeof(Hittable *));
     if (!list->objects)
       abort();
     list->capacity = n;
@@ -41,7 +38,7 @@ static void hittable_list_grow(HittableList *list, size_t n) {
   }
 }
 
-void hittable_list_add(HittableList *list, Hittable hittable) {
+void hittable_list_add(HittableList *list, const Hittable *hittable) {
   if (list->capacity == list->size)
     hittable_list_grow(list, list->capacity == 0 ? 16 : list->capacity);
   list->objects[list->size++] = hittable;
@@ -53,7 +50,7 @@ bool hittable_list_hit(const HittableList *list, Ray r, double t_min,
   double closest_so_far = t_max;
 
   for (size_t i = 0; i < list->size; ++i) {
-    if (hittable_hit(&list->objects[i], r, t_min, closest_so_far, record)) {
+    if (hittable_hit(list->objects[i], r, t_min, closest_so_far, record)) {
       hit_anything = true;
       closest_so_far = record->t;
     }
@@ -67,10 +64,6 @@ void hittable_list_free(HittableList *list) {
   list->objects = 0;
 }
 
-Hittable make_hittable_sphere(const Sphere *sphere) {
-  return (Hittable){.type = HITTABLE_SPHERE, sphere};
-}
-
 bool sphere_hit(const Sphere *sphere, Ray r, double t_min, double t_max,
                 HitRecord *record) {
   Vec3 oc = point3_sub(r.origin, sphere->center);

hittable.h

@@ -24,32 +24,29 @@ typedef enum HittableType {
 
 typedef struct Hittable {
   HittableType type;
-  const void *data;
 } Hittable;
 
 bool hittable_hit(const Hittable *hittable, Ray r, double t_min, double t_max,
                   HitRecord *record);
 
 typedef struct HittableList {
-  Hittable *objects;
+  HittableType type;
+  const Hittable **objects;
   size_t size;
   size_t capacity;
 } HittableList;
 
-Hittable make_hittable_list(const HittableList *list);
-
-void hittable_list_add(HittableList *list, Hittable hittable);
+void hittable_list_add(HittableList *list, const Hittable *hittable);
 bool hittable_list_hit(const HittableList *list, Ray r, double t_min,
                        double t_max, HitRecord *record);
 void hittable_list_free(HittableList *list);
 
 typedef struct Sphere {
+  HittableType type;
   Point3 center;
   double radius;
 } Sphere;
 
-Hittable make_hittable_sphere(const Sphere *sphere);
-
 bool sphere_hit(const Sphere *sphere, Ray r, double t_min, double t_max,
                 HitRecord *record);
 

main.c

@@ -11,12 +11,12 @@
 #include "utils.h"
 #include "vec3.h"
 
-Color ray_color(Ray r, Hittable world, int depth) {
+Color ray_color(Ray r, const Hittable *world, int depth) {
   if (depth <= 0)
     return (Color){0, 0, 0};
 
   HitRecord record;
-  if (hittable_hit(&world, r, 0.001, DBL_MAX, &record)) {
+  if (hittable_hit(world, r, 0.001, DBL_MAX, &record)) {
     Point3 target = point3_add(
         record.p, vec3_add(record.normal, vec3_random_unit_vector()));
     return color_mul(0.5,
@@ -39,16 +39,19 @@ int main(void) {
   const int max_depth = 50;
 
   /* World */
-  HittableList object_list = {0};
-  hittable_list_add(&object_list, make_hittable_sphere(&(Sphere){
+  HittableList world = {.type = HITTABLE_LIST};
+  Sphere sphere1 = {
+      .type = HITTABLE_SPHERE,
       .center = (Point3){0, 0, -1},
       .radius = 0.5,
-                                  }));
-  hittable_list_add(&object_list, make_hittable_sphere(&(Sphere){
+  };
+  Sphere sphere2 = {
+      .type = HITTABLE_SPHERE,
       .center = (Point3){0, -100.5, -1},
       .radius = 100,
-                                  }));
-  Hittable world = make_hittable_list(&object_list);
+  };
+  hittable_list_add(&world, (const Hittable *)&sphere1);
+  hittable_list_add(&world, (const Hittable *)&sphere2);
 
   /* Camera */
   Camera camera;
@@ -64,7 +67,8 @@ int main(void) {
         double u = (i + random_double()) / (image_width - 1);
         double v = (j + random_double()) / (image_height - 1);
         Ray r = camera_get_ray(&camera, u, v);
-        pixel_color = color_add(pixel_color, ray_color(r, world, max_depth));
+        pixel_color = color_add(
+            pixel_color, ray_color(r, (const Hittable *)&world, max_depth));
       }
       color_write(stdout, pixel_color, samples_per_pixel);
     }
@@ -72,7 +76,7 @@ int main(void) {
 
   fprintf(stderr, "\nDone.\n");
 
-  hittable_list_free(&object_list);
+  hittable_list_free(&world);
 
   return 0;
 }