movement: generalize; use vectors (#16)

Generalized movement, so that all entities move the same.

Reviewed-on: #16
Reviewed-by: raf <raf@notashelf.dev>
Co-authored-by: Squirrel Modeller <squirrelmodeller@protonmail.com>
Co-committed-by: Squirrel Modeller <squirrelmodeller@protonmail.com>

src/movement.c

@@ -0,0 +1,29 @@
+#include "movement.h"
+#include "enemy.h"
+#include "map.h"
+#include <stdbool.h>
+
+// Check if position is occupied by player
+static int is_player_at(Player *p, int x, int y) {
+  return (p->position.x == x && p->position.y == y);
+}
+
+MoveResult try_move_entity(Vec2 *p, Vec2 direction, Map *map, Player *player, Enemy *enemies, int enemy_count,
+                           bool moving_is_player) {
+  int new_x = p->x + direction.x;
+  int new_y = p->y + direction.y;
+
+  if (!is_floor(map, new_x, new_y))
+    return MOVE_RESULT_BLOCKED_WALL;
+
+  if (is_enemy_at(enemies, enemy_count, new_x, new_y))
+    return MOVE_RESULT_BLOCKED_ENEMY;
+  if (!moving_is_player) {
+    if (is_player_at(player, new_x, new_y))
+      return MOVE_RESULT_BLOCKED_PLAYER;
+  }
+
+  p->x = new_x;
+  p->y = new_y;
+  return MOVE_RESULT_MOVED;
+}