movement: generalize; use vectors (#16)

Generalized movement, so that all entities move the same.

Reviewed-on: NotAShelf/rogged#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.h

@@ -0,0 +1,17 @@
+#ifndef MOVEMENT_H
+#define MOVEMENT_H
+
+#include "common.h"
+
+typedef enum {
+  MOVE_RESULT_MOVED,
+  MOVE_RESULT_BLOCKED_WALL,
+  MOVE_RESULT_BLOCKED_PLAYER,
+  MOVE_RESULT_BLOCKED_ENEMY
+} MoveResult;
+
+// Attempts to move entity in a given direction. Returns outcome of action.
+MoveResult try_move_entity(Vec2 *p, Vec2 direction, Map *map, Player *player, Enemy *enemies, int enemy_count,
+                           bool moving_is_player);
+
+#endif  // MOVEMENT_H