Add hittable objects

build.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 CC=${CC:-"gcc"}
-CFLAGS=${CFLAGS:-"-Wall -Wextra -std=c18 -g"}
+CFLAGS=${CFLAGS:-"-Wall -Wextra -std=gnu18 -g -fsanitize=address"}
 LDFLAGS=${LDFLAGS:-"-lm"}
 MAIN_FILE=${MAIN_FILE:-"main.c"}
 

color.c

@@ -1,15 +1,15 @@
 #include "color.h"
 #include <stdio.h>
 
-color color_lerp(color c1, color c2, double t) {
-  return (color){
+Color color_lerp(Color c1, Color c2, double t) {
+  return (Color){
       (1.0 - t) * c1.r + t * c2.r,
       (1.0 - t) * c1.g + t * c2.g,
       (1.0 - t) * c1.b + t * c2.b,
   };
 }
 
-void color_write(FILE *out, color c) {
+void color_write(FILE *out, Color c) {
   fprintf(out, "%d %d %d\n", (int)(255.999 * c.r), (int)(255.999 * c.g),
           (int)(255.999 * c.b));
 }

color.h

@@ -3,12 +3,12 @@
 
 #include <stdio.h>
 
-typedef struct color {
+typedef struct Color {
   double r, g, b;
-} color;
+} Color;
 
-color color_lerp(color c1, color c2, double t);
+Color color_lerp(Color c1, Color c2, double t);
 
-void color_write(FILE *out, color c);
+void color_write(FILE *out, Color c);
 
 #endif /* INCLUDED_COLOR_H */

hittable.c

@@ -0,0 +1,98 @@
+#include "hittable.h"
+#include "point3.h"
+#include "vec3.h"
+
+#include <math.h>
+#include <stdlib.h>
+
+void hit_record_set_face_normal(HitRecord *record, Ray r, Vec3 outward_normal) {
+  record->front_face = vec3_dot(r.direction, outward_normal) < 0;
+  record->normal =
+      record->front_face ? outward_normal : vec3_neg(outward_normal);
+}
+
+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);
+  case HITTABLE_SPHERE:
+    return sphere_hit(hittable->data, 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);
+    if (!list->objects)
+      abort();
+    list->capacity = n;
+  } else {
+    list->objects = malloc(n * sizeof(Hittable));
+    if (!list->objects)
+      abort();
+    list->capacity = n;
+    list->size = 0;
+  }
+}
+
+void hittable_list_add(HittableList *list, Hittable hittable) {
+  if (list->capacity == list->size)
+    hittable_list_grow(list, list->capacity == 0 ? 16 : list->capacity);
+  list->objects[list->size++] = hittable;
+}
+
+bool hittable_list_hit(const HittableList *list, Ray r, double t_min,
+                       double t_max, HitRecord *record) {
+  bool hit_anything = false;
+  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)) {
+      hit_anything = true;
+      closest_so_far = record->t;
+    }
+  }
+
+  return hit_anything;
+}
+
+void hittable_list_free(HittableList *list) {
+  free(list->objects);
+  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);
+  double a = vec3_length2(r.direction);
+  double half_b = vec3_dot(oc, r.direction);
+  double c = vec3_length2(oc) - sphere->radius * sphere->radius;
+  double discriminant = half_b * half_b - a * c;
+  if (discriminant < 0)
+    return false;
+
+  double square_root = sqrt(discriminant);
+  double root = (-half_b - square_root) / a;
+  if (root < t_min || t_max < root) {
+    root = (-half_b + square_root) / a;
+    if (root < t_min || t_max < root)
+      return false;
+  }
+
+  record->t = root;
+  record->p = ray_at(r, root);
+  Vec3 outward_normal =
+      vec3_div(point3_sub(record->p, sphere->center), sphere->radius);
+  hit_record_set_face_normal(record, r, outward_normal);
+  return true;
+}

hittable.h

@@ -0,0 +1,56 @@
+#ifndef INCLUDED_HITTABLE_H
+#define INCLUDED_HITTABLE_H
+
+#include "point3.h"
+#include "ray.h"
+#include "vec3.h"
+
+#include <stdbool.h>
+#include <stddef.h>
+
+typedef struct HitRecord {
+  Point3 p;
+  Vec3 normal;
+  double t;
+  bool front_face;
+} HitRecord;
+
+void hit_record_set_face_normal(HitRecord *record, Ray r, Vec3 outward_normal);
+
+typedef enum HittableType {
+  HITTABLE_LIST,
+  HITTABLE_SPHERE,
+} 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;
+  size_t size;
+  size_t capacity;
+} HittableList;
+
+Hittable make_hittable_list(const HittableList *list);
+
+void hittable_list_add(HittableList *list, 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 {
+  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);
+
+#endif /* INCLUDED_HITTABLE_H */

main.c

@@ -1,34 +1,24 @@
+#include <float.h>
 #include <math.h>
 #include <stdbool.h>
 #include <stdio.h>
 
 #include "color.h"
+#include "hittable.h"
 #include "point3.h"
 #include "ray.h"
 #include "vec3.h"
 
-double hit_sphere(point3 center, double radius, ray r) {
-  vec3 oc = point3_sub(r.origin, center);
-  double a = vec3_length2(r.direction);
-  double half_b = vec3_dot(oc, r.direction);
-  double c = vec3_length2(oc) - radius * radius;
-  double discriminant = half_b * half_b - a * c;
-  if (discriminant < 0)
-    return -1.0;
-  else
-    return (-half_b - sqrt(discriminant)) / a;
-}
-
-color ray_color(ray r) {
-  double t = hit_sphere((point3){0, 0, -1}, 0.5, r);
-  if (t > 0.0) {
-    vec3 n = vec3_normalize(point3_sub(ray_at(r, t), (point3){0, 0, -1}));
-    return (color){0.5 * (n.x + 1), 0.5 * (n.y + 1), 0.5 * (n.z + 1)};
+Color ray_color(Ray r, Hittable world) {
+  HitRecord record;
+  if (hittable_hit(&world, r, 0, DBL_MAX, &record)) {
+    return (Color){0.5 * (record.normal.x + 1), 0.5 * (record.normal.y + 1),
+                   0.5 * (record.normal.z + 1)};
   }
-  vec3 unit_direction = vec3_normalize(r.direction);
-  t = 0.5 * (unit_direction.y + 1.0);
-  color gradient1 = {1.0, 1.0, 1.0};
-  color gradient2 = {0.5, 0.7, 1.0};
+  Vec3 unit_direction = vec3_normalize(r.direction);
+  double t = 0.5 * (unit_direction.y + 1.0);
+  Color gradient1 = {1.0, 1.0, 1.0};
+  Color gradient2 = {0.5, 0.7, 1.0};
   return color_lerp(gradient1, gradient2, t);
 }
 
@@ -38,17 +28,28 @@ int main(void) {
   const int image_width = 256;
   const int image_height = (int)(image_width / aspect_ratio);
 
+  /* World */
+  HittableList world = {0};
+  hittable_list_add(&world, make_hittable_sphere(&(Sphere){
+                                .center = (Point3){0, 0, -1},
+                                .radius = 0.5,
+                            }));
+  hittable_list_add(&world, make_hittable_sphere(&(Sphere){
+                                .center = (Point3){0, -100.5, -1},
+                                .radius = 100,
+                            }));
+
   /* Camera parameters */
   double viewport_height = 2;
   double viewport_width = aspect_ratio * viewport_height;
   double focal_length = 1.0;
 
-  point3 origin = {0};
-  vec3 horizontal = {viewport_width, 0, 0};
-  vec3 vertical = {0, viewport_height, 0};
-  vec3 offset = vec3_add(vec3_div(horizontal, 2), vec3_div(vertical, 2));
-  offset = vec3_add(offset, (vec3){0, 0, focal_length});
-  point3 lower_left_corner = point3_add(origin, vec3_neg(offset));
+  Point3 origin = {0};
+  Vec3 horizontal = {viewport_width, 0, 0};
+  Vec3 vertical = {0, viewport_height, 0};
+  Vec3 offset = vec3_add(vec3_div(horizontal, 2), vec3_div(vertical, 2));
+  offset = vec3_add(offset, (Vec3){0, 0, focal_length});
+  Point3 lower_left_corner = point3_add(origin, vec3_neg(offset));
 
   printf("P3\n%u %u\n255\n", image_width, image_height);
 
@@ -57,22 +58,26 @@ int main(void) {
     for (int i = 0; i < image_width; ++i) {
       double u = (double)i / (image_width - 1);
       double v = (double)j / (image_height - 1);
-      point3 screen_point =
+      Point3 screen_point =
           point3_add(lower_left_corner,
                      vec3_add(vec3_mul(u, horizontal), vec3_mul(v, vertical)));
-      vec3 direction = point3_sub(screen_point, origin);
-      ray r = {origin, direction};
-      color pixel_color = ray_color(r);
+      Vec3 direction = point3_sub(screen_point, origin);
+      Ray r = {origin, direction};
+      Color pixel_color = ray_color(r, make_hittable_list(&world));
       color_write(stdout, pixel_color);
     }
   }
 
   fprintf(stderr, "\nDone.\n");
 
+  hittable_list_free(&world);
+
   return 0;
 }
 
 #include "color.c"
+#include "hittable.c"
 #include "point3.c"
 #include "ray.c"
+#include "utils.c"
 #include "vec3.c"

point3.c

@@ -1,9 +1,9 @@
 #include "point3.h"
 
-point3 point3_add(point3 p, vec3 v) {
-  return (point3){p.x + v.x, p.y + v.y, p.z + v.z};
+Point3 point3_add(Point3 p, Vec3 v) {
+  return (Point3){p.x + v.x, p.y + v.y, p.z + v.z};
 }
 
-vec3 point3_sub(point3 p1, point3 p2) {
-  return (vec3){p1.x - p2.x, p1.y - p2.y, p1.z - p2.z};
+Vec3 point3_sub(Point3 p1, Point3 p2) {
+  return (Vec3){p1.x - p2.x, p1.y - p2.y, p1.z - p2.z};
 }

point3.h

@@ -3,11 +3,11 @@
 
 #include "vec3.h"
 
-typedef struct point3 {
+typedef struct Point3 {
   double x, y, z;
-} point3;
+} Point3;
 
-point3 point3_add(point3 p, vec3 v);
-vec3 point3_sub(point3 p1, point3 p2);
+Point3 point3_add(Point3 p, Vec3 v);
+Vec3 point3_sub(Point3 p1, Point3 p2);
 
 #endif /* INCLUDED_POINT3_H */

ray.c

@@ -1,6 +1,6 @@
 #include "ray.h"
 #include "point3.h"
 
-point3 ray_at(ray r, double t) {
+Point3 ray_at(Ray r, double t) {
   return point3_add(r.origin, vec3_mul(t, r.direction));
 }

ray.h

@@ -4,11 +4,11 @@
 #include "point3.h"
 #include "vec3.h"
 
-typedef struct ray {
-  point3 origin;
-  vec3 direction;
-} ray;
+typedef struct Ray {
+  Point3 origin;
+  Vec3 direction;
+} Ray;
 
-point3 ray_at(ray r, double t);
+Point3 ray_at(Ray r, double t);
 
 #endif /* INCLUDED_RAY_H */

utils.c

@@ -0,0 +1,7 @@
+#include "utils.h"
+
+#include <math.h>
+
+double degrees_to_radians(double degrees) {
+    return degrees * M_PI / 180.0;
+}

utils.h

@@ -0,0 +1,6 @@
+#ifndef INCLUDED_UTILS_H
+#define INCLUDED_UTILS_H
+
+double degrees_to_radians(double degrees);
+
+#endif /* INCLUDED_UTILS_H */

vec3.c

@@ -2,32 +2,32 @@
 
 #include <math.h>
 
-vec3 vec3_neg(vec3 v) { return (vec3){-v.x, -v.y, -v.z}; }
+Vec3 vec3_neg(Vec3 v) { return (Vec3){-v.x, -v.y, -v.z}; }
 
-vec3 vec3_add(vec3 v1, vec3 v2) {
-  return (vec3){v1.x + v2.x, v1.y + v2.y, v1.z + v2.z};
+Vec3 vec3_add(Vec3 v1, Vec3 v2) {
+  return (Vec3){v1.x + v2.x, v1.y + v2.y, v1.z + v2.z};
 }
 
-vec3 vec3_sub(vec3 v1, vec3 v2) {
-  return (vec3){v1.x - v2.x, v1.y - v2.y, v1.z - v2.z};
+Vec3 vec3_sub(Vec3 v1, Vec3 v2) {
+  return (Vec3){v1.x - v2.x, v1.y - v2.y, v1.z - v2.z};
 }
 
-vec3 vec3_mul(double c, vec3 v) { return (vec3){c * v.x, c * v.y, c * v.z}; }
+Vec3 vec3_mul(double c, Vec3 v) { return (Vec3){c * v.x, c * v.y, c * v.z}; }
 
-vec3 vec3_div(vec3 v, double c) { return (vec3){v.x / c, v.y / c, v.z / c}; }
+Vec3 vec3_div(Vec3 v, double c) { return (Vec3){v.x / c, v.y / c, v.z / c}; }
 
-double vec3_length(vec3 v) { return sqrt(vec3_length2(v)); }
+double vec3_length(Vec3 v) { return sqrt(vec3_length2(v)); }
 
-double vec3_length2(vec3 v) { return v.x * v.x + v.y * v.y + v.z * v.z; }
+double vec3_length2(Vec3 v) { return v.x * v.x + v.y * v.y + v.z * v.z; }
 
-vec3 vec3_normalize(vec3 v) { return vec3_div(v, vec3_length(v)); }
+Vec3 vec3_normalize(Vec3 v) { return vec3_div(v, vec3_length(v)); }
 
-double vec3_dot(vec3 v1, vec3 v2) {
+double vec3_dot(Vec3 v1, Vec3 v2) {
   return v1.x * v2.x + v1.y * v2.y + v1.z * v2.z;
 }
 
-vec3 vec3_cross(vec3 v1, vec3 v2) {
-  return (vec3){
+Vec3 vec3_cross(Vec3 v1, Vec3 v2) {
+  return (Vec3){
       v1.y * v2.z - v1.z * v2.y,
       v1.z * v2.x - v1.x * v2.z,
       v1.x * v2.y - v1.y * v2.x,

vec3.h

@@ -1,22 +1,22 @@
 #ifndef INCLUDED_VEC3_H
 #define INCLUDED_VEC3_H
 
-typedef struct vec3 {
+typedef struct Vec3 {
   double x, y, z;
-} vec3;
+} Vec3;
 
-vec3 vec3_neg(vec3 v);
-vec3 vec3_add(vec3 v1, vec3 v2);
-vec3 vec3_sub(vec3 v1, vec3 v2);
-vec3 vec3_mul(double c, vec3 v);
-vec3 vec3_div(vec3 v, double c);
+Vec3 vec3_neg(Vec3 v);
+Vec3 vec3_add(Vec3 v1, Vec3 v2);
+Vec3 vec3_sub(Vec3 v1, Vec3 v2);
+Vec3 vec3_mul(double c, Vec3 v);
+Vec3 vec3_div(Vec3 v, double c);
 
-double vec3_length(vec3 v);
-double vec3_length2(vec3 v);
+double vec3_length(Vec3 v);
+double vec3_length2(Vec3 v);
 
-vec3 vec3_normalize(vec3 v);
+Vec3 vec3_normalize(Vec3 v);
 
-double vec3_dot(vec3 v1, vec3 v2);
-vec3 vec3_cross(vec3 v1, vec3 v2);
+double vec3_dot(Vec3 v1, Vec3 v2);
+Vec3 vec3_cross(Vec3 v1, Vec3 v2);
 
 #endif /* INCLUDED_VEC3_H */