Update colours

compile

@@ -2,9 +2,10 @@
 
 CC=clang
 CFLAGS="-g -Wall -Werror -pedantic -Iinclude $(pkg-config --cflags sdl2)"
-LIBS="$(pkg-config --libs sdl2)"
+LIBS="$(pkg-config --libs sdl2) -lm"
 
 RAYTRACER_SRC="src/window/*.c \
+	src/vector/*.c \
 	src/raytracer/*.c \
 "
 

include/vector/vec.h

@@ -0,0 +1,53 @@
+#ifndef VEC_H
+#define VEC_H
+
+#include "c_cpp_aliases/aliases.h"
+
+typedef struct {
+  i32 x;
+  i32 y;
+} vec2i_t;
+
+typedef struct {
+  f32 x;
+  f32 y;
+} vec2f_t;
+
+typedef struct {
+  i32 x;
+  i32 y;
+  i32 z;
+} vec3i_t;
+
+typedef struct {
+  f32 x;
+  f32 y;
+  f32 z;
+} vec3f_t;
+
+#define vec_add(T, v1, v2) vec_add_##T(v1, v2)
+#define vec_sub(T, v1, v2) vec_sub_##T(v1, v2)
+#define vec_mul(T, v1, v2) vec_mul_##T(v1, v2)
+#define vec_dot(T, v1, v2) vec_dot_##T(v1, v2)
+
+vec2i_t vec_add_vec2i_t(vec2i_t v1, vec2i_t v2);
+vec2i_t vec_sub_vec2i_t(vec2i_t v1, vec2i_t v2);
+vec2i_t vec_mul_vec2i_t(vec2i_t v1, vec2i_t v2);
+i32 vec_dot_vec2i_t(vec2i_t v1, vec2i_t v2);
+
+vec2f_t vec_add_vec2f_t(vec2f_t v1, vec2f_t v2);
+vec2f_t vec_sub_vec2f_t(vec2f_t v1, vec2f_t v2);
+vec2f_t vec_mul_vec2f_t(vec2f_t v1, vec2f_t v2);
+f32 vec_dot_vec2f_t(vec2f_t v1, vec2f_t v2);
+
+vec3i_t vec_add_vec3i_t(vec3i_t v1, vec3i_t v2);
+vec3i_t vec_sub_vec3i_t(vec3i_t v1, vec3i_t v2);
+vec3i_t vec_mul_vec3i_t(vec3i_t v1, vec3i_t v2);
+i32 vec_dot_vec3i_t(vec3i_t v1, vec3i_t v2);
+
+vec3f_t vec_add_vec3f_t(vec3f_t v1, vec3f_t v2);
+vec3f_t vec_sub_vec3f_t(vec3f_t v1, vec3f_t v2);
+vec3f_t vec_mul_vec3f_t(vec3f_t v1, vec3f_t v2);
+f32 vec_dot_vec3f_t(vec3f_t v1, vec3f_t v2);
+
+#endif // !VEC_H

include/window/window.h

@@ -2,6 +2,7 @@
 #define WINDOW_H
 
 #include "c_cpp_aliases/aliases.h"
+#include "vector/vec.h"
 #include <SDL2/SDL_video.h>
 #include <stdbool.h>
 
@@ -30,4 +31,6 @@ void clear_window(window_t *wnd, colour_t colour);
 void set_pixel(window_t *wnd, i32 x, i32 y, colour_t colour);
 void swap_buffers(window_t *wnd);
 
+vec3f_t window_to_viewport(window_t *wnd, i32 x, i32 y, vec3f_t viewport);
+
 #endif // !WINDOW_H

src/raytracer/main.c

@@ -1,22 +1,77 @@
 #include "SDL_events.h"
 #include "c_cpp_aliases/aliases.h"
+#include "vector/vec.h"
 #include "window/window.h"
+#include <math.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 
+#define ARR_LEN(ARR) sizeof(ARR) / sizeof(ARR[0])
+
+typedef struct {
+  f32 radius;
+  vec3f_t centre;
+  colour_t colour;
+} sphere_t;
+
+typedef struct {
+  sphere_t *spheres;
+  u32 count;
+} scene_t;
+
+typedef struct {
+  f32 t1;
+  f32 t2;
+} solutions_t;
+
+solutions_t ray_intersects_sphere(vec3f_t origin, vec3f_t direction,
+                                  sphere_t sphere);
+colour_t trace_ray(vec3f_t origin, vec3f_t direction, f32 t_min, f32 t_max,
+                   const scene_t *scene, colour_t default_colour);
+
 int main(int argc, char *argv[]) {
-  colour_t bg = (colour_t){.r = 128, .g = 128, .b = 128, .a = 255};
+  colour_t bg = (colour_t){.r = 27, .g = 38, .b = 79, .a = 255};
+  vec3f_t camera = {.x = 0.0f, .y = 0.0f, .z = 0.0f};
+  vec3f_t viewport = {.x = 1.0f, .y = 1.0f, .z = 1.0f};
 
   window_t window = {0};
 
-  if (!init_window(&window, 1000, 800, "CG From Scratch")) {
+  if (!init_window(&window, 800, 800, "CG From Scratch")) {
     return EXIT_FAILURE;
   }
 
   bool running = true;
   SDL_Event event = {0};
 
+  sphere_t spheres[] = {
+      (sphere_t){
+          .radius = 1.0f,
+          .centre = (vec3f_t){.x = 0.0f, .y = -1.0f, .z = 3.0f},
+          .colour = (colour_t){.r = 245, .g = 238, .b = 158, .a = 255},
+      },
+      (sphere_t){
+          .radius = 1.0f,
+          .centre = (vec3f_t){.x = -2.0f, .y = 0.0f, .z = 4.0f},
+          .colour = (colour_t){.r = 59, .g = 142, .b = 165, .a = 255},
+      },
+      (sphere_t){
+          .radius = 1.0f,
+          .centre = (vec3f_t){.x = 2.0f, .y = 0.0f, .z = 4.0f},
+          .colour = (colour_t){.r = 171, .g = 52, .b = 40, .a = 255},
+      },
+  };
+
+  scene_t scene = {
+      .spheres = spheres,
+      .count = ARR_LEN(spheres),
+  };
+
+  i32 w_min = ((i32)window.half_width) * -1;
+  i32 w_max = (i32)window.half_width;
+  i32 h_min = ((i32)window.half_height) * -1;
+  i32 h_max = (i32)window.half_height;
+
   while (running) {
     while (SDL_PollEvent(&event)) {
       switch (event.type) {
@@ -28,6 +83,14 @@ int main(int argc, char *argv[]) {
 
     clear_window(&window, bg);
 
+    for (i32 y = h_min; y < h_max; ++y) {
+      for (i32 x = w_min; x < w_max; ++x) {
+        vec3f_t direction = window_to_viewport(&window, x, y, viewport);
+        colour_t colour = trace_ray(camera, direction, 1, INFINITY, &scene, bg);
+        set_pixel(&window, x, y, colour);
+      }
+    }
+
     swap_buffers(&window);
   }
 
@@ -35,3 +98,52 @@ int main(int argc, char *argv[]) {
 
   return EXIT_SUCCESS;
 }
+
+solutions_t ray_intersects_sphere(vec3f_t origin, vec3f_t direction,
+                                  sphere_t sphere) {
+  f32 r = sphere.radius;
+  vec3f_t CO = vec_sub(vec3f_t, origin, sphere.centre);
+
+  f32 a = vec_dot(vec3f_t, direction, direction);
+  f32 b = 2.0f * vec_dot(vec3f_t, CO, direction);
+  f32 c = vec_dot(vec3f_t, CO, CO) - r * r;
+
+  f32 discriminant = b * b - 4 * a * c;
+  if (discriminant < 0) {
+    return (solutions_t){INFINITY, INFINITY};
+  }
+
+  f32 t1 = (-b + sqrtf(discriminant)) / (2 * a);
+  f32 t2 = (-b - sqrtf(discriminant)) / (2 * a);
+
+  return (solutions_t){t1, t2};
+}
+
+colour_t trace_ray(vec3f_t origin, vec3f_t direction, f32 t_min, f32 t_max,
+                   const scene_t *scene, colour_t default_colour) {
+  f32 closest_t = INFINITY;
+  sphere_t *closest_sphere = NULL;
+
+  for (u32 i = 0; i < scene->count; ++i) {
+    solutions_t solutions =
+        ray_intersects_sphere(origin, direction, scene->spheres[i]);
+
+    if (solutions.t1 >= t_min && solutions.t1 <= t_max &&
+        solutions.t1 < closest_t) {
+      closest_t = solutions.t1;
+      closest_sphere = &(scene->spheres[i]);
+    }
+
+    if (solutions.t2 >= t_min && solutions.t2 <= t_max &&
+        solutions.t2 < closest_t) {
+      closest_t = solutions.t2;
+      closest_sphere = &(scene->spheres[i]);
+    }
+  }
+
+  if (!closest_sphere) {
+    return default_colour;
+  }
+
+  return closest_sphere->colour;
+}

src/vector/vec.c

@@ -0,0 +1,65 @@
+#include "vector/vec.h"
+
+vec2i_t vec_add_vec2i_t(vec2i_t v1, vec2i_t v2) {
+  return (vec2i_t){.x = v1.x + v2.x, .y = v1.y + v2.y};
+}
+
+vec2i_t vec_sub_vec2i_t(vec2i_t v1, vec2i_t v2) {
+  return (vec2i_t){.x = v1.x - v2.x, .y = v1.y - v2.y};
+}
+
+vec2i_t vec_mul_vec2i_t(vec2i_t v1, vec2i_t v2) {
+  return (vec2i_t){.x = v1.x * v2.x, .y = v1.y * v2.y};
+}
+
+i32 vec_dot_vec2i_t(vec2i_t v1, vec2i_t v2) {
+  return v1.x * v2.x + v1.y * v2.y;
+}
+
+vec2f_t vec_add_vec2f_t(vec2f_t v1, vec2f_t v2) {
+  return (vec2f_t){.x = v1.x + v2.x, .y = v1.y + v2.y};
+}
+
+vec2f_t vec_sub_vec2f_t(vec2f_t v1, vec2f_t v2) {
+  return (vec2f_t){.x = v1.x - v2.x, .y = v1.y - v2.y};
+}
+
+vec2f_t vec_mul_vec2f_t(vec2f_t v1, vec2f_t v2) {
+  return (vec2f_t){.x = v1.x * v2.x, .y = v1.y * v2.y};
+}
+
+f32 vec_dot_vec2f_t(vec2f_t v1, vec2f_t v2) {
+  return v1.x * v2.x + v1.y * v2.y;
+}
+
+vec3i_t vec_add_vec3i_t(vec3i_t v1, vec3i_t v2) {
+  return (vec3i_t){.x = v1.x + v2.x, .y = v1.y + v2.y, .z = v1.z + v2.z};
+}
+
+vec3i_t vec_sub_vec3i_t(vec3i_t v1, vec3i_t v2) {
+  return (vec3i_t){.x = v1.x - v2.x, .y = v1.y - v2.y, .z = v1.z - v2.z};
+}
+
+vec3i_t vec_mul_vec3i_t(vec3i_t v1, vec3i_t v2) {
+  return (vec3i_t){.x = v1.x * v2.x, .y = v1.y * v2.y, .z = v1.z * v2.z};
+}
+
+i32 vec_dot_vec3i_t(vec3i_t v1, vec3i_t v2) {
+  return v1.x * v2.x + v1.y * v2.y + v1.z * v2.z;
+}
+
+vec3f_t vec_add_vec3f_t(vec3f_t v1, vec3f_t v2) {
+  return (vec3f_t){.x = v1.x + v2.x, .y = v1.y + v2.y, .z = v1.z + v2.z};
+}
+
+vec3f_t vec_sub_vec3f_t(vec3f_t v1, vec3f_t v2) {
+  return (vec3f_t){.x = v1.x - v2.x, .y = v1.y - v2.y, .z = v1.z - v2.z};
+}
+
+vec3f_t vec_mul_vec3f_t(vec3f_t v1, vec3f_t v2) {
+  return (vec3f_t){.x = v1.x * v2.x, .y = v1.y * v2.y, .z = v1.z * v2.z};
+}
+
+f32 vec_dot_vec3f_t(vec3f_t v1, vec3f_t v2) {
+  return v1.x * v2.x + v1.y * v2.y + v1.z * v2.z;
+}

src/window/window.c

@@ -1,5 +1,6 @@
 #include "window/window.h"
 #include "c_cpp_aliases/aliases.h"
+#include "vector/vec.h"
 #include <SDL2/SDL.h>
 #include <SDL2/SDL_error.h>
 #include <SDL2/SDL_pixels.h>
@@ -10,6 +11,7 @@
 u32 colour_to_u32(colour_t colour);
 u32 index_from_coordinates(window_t *wnd, u32 x, u32 y);
 i32 denormalise(i32 value, u32 max, u32 abs_half);
+vec2i_t denormalised_coords(const window_t *wnd, i32 x, i32 y);
 void set_screen_pixel(window_t *wnd, u32 x, u32 y, colour_t colour);
 
 bool init_window(window_t *wnd, u32 width, u32 height, const char *title) {
@@ -103,16 +105,15 @@ void clear_window(window_t *wnd, colour_t colour) {
 }
 
 void set_pixel(window_t *wnd, i32 x, i32 y, colour_t colour) {
-  i32 screen_x = denormalise(x, wnd->width, wnd->half_width);
-  i32 screen_y = denormalise(-y, wnd->height, wnd->half_height);
+  vec2i_t coords = denormalised_coords(wnd, x, y);
 
-  if (screen_x < 0 || screen_y < 0) {
+  if (coords.x < 0 || coords.y < 0) {
     return;
   }
 
   SDL_LockSurface(wnd->back_buffer);
 
-  set_screen_pixel(wnd, (u32)screen_x, (u32)screen_y, colour);
+  set_screen_pixel(wnd, (u32)(coords.x), (u32)(coords.y), colour);
 
   SDL_UnlockSurface(wnd->back_buffer);
 }
@@ -150,6 +151,13 @@ i32 denormalise(i32 value, u32 max, u32 abs_half) {
   return denormalised;
 }
 
+vec2i_t denormalised_coords(const window_t *wnd, i32 x, i32 y) {
+  i32 screen_x = denormalise(x, wnd->width, wnd->half_width);
+  i32 screen_y = denormalise(-y, wnd->height, wnd->half_height);
+
+  return (vec2i_t){.x = screen_x, .y = screen_y};
+}
+
 void set_screen_pixel(window_t *wnd, u32 x, u32 y, colour_t colour) {
   u32 index = index_from_coordinates(wnd, x, y);
   u32 c = colour_to_u32(colour);
@@ -158,3 +166,11 @@ void set_screen_pixel(window_t *wnd, u32 x, u32 y, colour_t colour) {
 
   pixels[index] = c;
 }
+
+vec3f_t window_to_viewport(window_t *wnd, i32 x, i32 y, vec3f_t viewport) {
+  return (vec3f_t){
+      .x = x * viewport.x / wnd->width,
+      .y = y * viewport.y / wnd->height,
+      .z = viewport.z,
+  };
+}