things/sim/cellular/main.c

// x-run: make run
#include <raylib.h>
#include <stdlib.h>
#include <string.h>

struct cell {
  int origin_x, origin_y;
  int random_seed;
  enum cell_type {
    CELL_VOID,
    CELL_LIVING,
    CELL_DEAD
  } type;
  int timer;
};

#define GET_CELL(A, X, Y) (A[((X + width) % width) + ((Y + height) % height) * width])

const int width = 400, height = 300;

Color cell_get_color(struct cell *cells, int x, int y);
void cell_update(struct cell *cells_old, struct cell *cells, int x, int y);

int main(int argc, char **argv) {
  InitWindow(width * 2, height * 2, "sim/cellular_NAME");
  SetTargetFPS(60);

  struct cell *cells = calloc(width * height, sizeof(struct cell));
  struct cell *cells_old = calloc(width * height, sizeof(struct cell));

  for (int y = 0; y < height; y++) {
    for (int x = 0; x < width; x++) {
      cells[x + y * width].origin_x = x;
      cells[x + y * width].origin_y = y;
      cells[x + y * width].random_seed = rand();
      cells[x + y * width].type = rand() % 100 == 0;
      cells[x + y * width].timer = 200;
    }
  }

  Image img_out = GenImageColor(width, height, BLANK);
  Texture2D tex_out = LoadTextureFromImage(img_out);

  while (!WindowShouldClose()) {
    memcpy(cells_old, cells, width * height * sizeof(struct cell));
    for (int y = 0; y < height; y++) {
      for (int x = 0; x < width; x++) {
        cell_update(cells_old, cells, x, y);
      }
    }
    BeginDrawing();
    ClearBackground(BLACK);
    for (int y = 0; y < height; y++) {
      for (int x = 0; x < width; x++) {
        struct cell cell = cells[x + y * width];
        ImageDrawPixel(&img_out, x, y, cell_get_color(cells, x, y));
      }
    }
    UpdateTexture(tex_out, img_out.data);
    DrawTextureEx(tex_out, (Vector2){ 0, 0 }, 0, 2, WHITE);
    DrawFPS(10, 10);
    EndDrawing();
  }
  UnloadTexture(tex_out);
  UnloadImage(img_out);
}

Color cell_get_color(struct cell *cells, int x, int y) {
  Vector3 color = ColorToHSV(WHITE);

  struct cell cell = cells[x + y * width];

  switch (cell.type) {
    case CELL_VOID: color = ColorToHSV(BLACK); break;
    case CELL_LIVING: color = ColorToHSV(DARKGREEN); break;
    case CELL_DEAD: color = ColorToHSV(RED); break;
  }

  color.x += (cell.random_seed % 60) - 30;
  color.y *= 1.0 - 0.2 * ((float)(cell.random_seed % 100) / 100.0);
  /*color.z *= cell.timer / 200.0;*/

  return ColorFromHSV(color.x, color.y, color.z);
}

void cell_update(struct cell *cells_old, struct cell *cells, int x, int y) {
  struct cell *old_self = &cells_old[x + y * width];
  struct cell *self = &cells[x + y * width];

  switch (self->type) {
    case CELL_LIVING:
      {
        for (int oy = -1; oy <= 1; oy++) {
          for (int ox = -1; ox <= 1; ox++) {
            struct cell old_other = GET_CELL(cells_old, x + ox, y + oy);
            struct cell *other = &GET_CELL(cells, x + ox, y + oy);
            if (old_other.type == CELL_VOID && rand() % 100 == 0) {
              other->type = CELL_LIVING;
              other->timer = 200;
            } else if (old_other.type == CELL_LIVING && rand() % 90 == 0) {
              other->type = CELL_DEAD;
              other->timer = rand() % 200;
            }
          }
        }
      }
      break;
    case CELL_DEAD:
      self->timer -= rand() % 8;
      if (self->timer <= 0) {
        self->type = CELL_VOID;
      }
    default:
      break;
  }
}