domino-dungeon/domino.c

#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include "domino.h"

#define DIRECTIONS 6
const struct eye direction[DIRECTIONS] = {
  {.x =  0, .y = -1},
  {.x = -2, .y =  0},
  {.x =  1, .y =  0},
  {.x =  0, .y =  1},
  {.x = -1, .y = -1},
  {.x = -1, .y =  1},
};

void bricks_append(struct bricks *bricks, struct brick brick) {
  if (bricks->count+1 > bricks->capacity) {
    if (bricks->capacity == 0) bricks->capacity = 256;
    while (bricks->count+1 > bricks->capacity) bricks->capacity *= 2;
    bricks->items.brick = realloc(bricks->items.brick, bricks->capacity * sizeof(*bricks->items.brick));
  }
  bricks->items.brick[bricks->count++] = brick;
}

void brick_print(const struct brick b) {
  struct eye *eyes = (struct eye*) &b;
  for (size_t i = 0; i < 2; i++) {
    printf("{.x = %d, .y =   %d, .val = %d, .vertical = %d}" , eyes[i].x, eyes[i].y, eyes[i].val, eyes[i].vertical); }
  printf("\n");
}


void brick_previews(const struct brick active, const struct bricks bricks, struct bricks *preview) {
  preview->count = 0;
  for (size_t i = 0; i < bricks.count * 2; i++) {
    struct eye e = bricks.items.eye[i];
    if (e.val != active.front.val && e.val != active.back.val) continue;

    struct brick p = active;

    p.front.x = e.x;
    p.front.y = e.y;
    p.back.x =  e.x + !active.front.vertical;
    p.back.y =  e.y +  active.front.vertical;

    struct brick previews[DIRECTIONS] = {0};
    for (size_t ii = 0; ii < DIRECTIONS; ii++) {
      int offset_x = active.front.vertical ? direction[ii].y : direction[ii].x;
      int offset_y = active.front.vertical ? direction[ii].x : direction[ii].y;
      previews[ii] = p;
      previews[ii].front.x += offset_x;
      previews[ii].front.y += offset_y;
      previews[ii].front.val = 0;

      previews[ii].back.x += offset_x;
      previews[ii].back.y += offset_y;

      for (size_t iii = 0; iii < bricks.count * 2; iii++) {
        previews[ii].front.val |= (
            (bricks.items.eye[iii].x == previews[ii].back.x && bricks.items.eye[iii].y == previews[ii].back.y) ||
            (bricks.items.eye[iii].x == previews[ii].front.x && bricks.items.eye[iii].y == previews[ii].front.y)
            || (
              (active.front.val != active.back.val) &&
              ((e.val == active.front.val && direction[ii].x < 0) || (e.val == active.back.val  && direction[ii].x >= 0))
            )
            );
      }
      if (!previews[ii].front.val) {
        previews[ii].front.val = p.front.val;
        bricks_append(preview, previews[ii]);
      }
    }
  }
}