pikuma_graphics_from_scratch/src/main.c

#include <stdint.h>
#include <stdbool.h>
#include <SDL2/SDL.h>
#include "display.h"
#include "vector.h"

////////////////////////////////////////////////////////////
// Declare an array of points
////////////////////////////////////////////////////////////
#define N_POINTS  (9 * 9 * 9)
vec3_t cube_points[N_POINTS];
vec2_t projected_points[N_POINTS];
float fov_factor = 128;


bool is_running = false;

void setup(void) {
  // Allocate the required memory in bytes to hold color buffer
  color_buffer = (uint32_t *) malloc(sizeof(uint32_t) * window_width * window_height);

  // Creating the SDL Texture that is uses to display the color buffer
  color_buffer_texture = SDL_CreateTexture(
    renderer,
    SDL_PIXELFORMAT_ARGB8888,
    SDL_TEXTUREACCESS_STREAMING,
    window_width,
    window_height
  );
  int point_count = 0;
  for (float x = -1; x <= 1; x += 0.25) {
    for (float y = -1; y <= 1; y += 0.25) {
      for (float z = -1; z <= 1; z += 0.25) {
        vec3_t new_point = { .x = x, .y = y, .z = z };
        cube_points[point_count++] = new_point;
      }
    }
  }
}

void process_input(void) {
  SDL_Event event;
  SDL_PollEvent(&event);

  switch (event.type) {
    case SDL_QUIT:
      is_running = false;
      break;
    case SDL_KEYDOWN:
      if (event.key.keysym.sym == SDLK_ESCAPE) {
        is_running = false;
      }
      break;
  }
}

////////////////////////////////////////////////////////////////////////////////
// Function that receives a 3d Vector and returns a 2d projected point
////////////////////////////////////////////////////////////////////////////////
vec2_t project(vec3_t point) {
  vec2_t projected_point = {
    .x = (fov_factor * point.x),
    .y = (fov_factor * point.y),
  };
  return projected_point;
}


void update(void) {
    for (int i = 0; i < N_POINTS; i++){
        vec3_t point = cube_points[i];
        vec2_t projected_point = project(point);
        
        projected_points[i] = projected_point;
    }
}


void render(void) {
  draw_grid();

  for (int i = 0; i < N_POINTS; i++){
    vec2_t projected_point = projected_points[i];
    draw_rect(
      projected_point.x + (window_width/2),
      projected_point.y + (window_height/2),
      4,
      4,
      0xFFFFFF00
    );
  }

  render_color_buffer();
  clear_color_buffer(0xFF000000);

  SDL_RenderPresent(renderer);
}


int main(void) {
  is_running = initialize_window();
  setup();

  while (is_running) {
    process_input();
    update();
    render();
  }
  destroy_window();
  return 0;
}