Setup rpg stuff

src/rpg/world/worldunit.h

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+/**
+ * Copyright (c) 2025 Dominic Masters
+ * 
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#pragma once
+#include "dusk.h"
+
+/**
+ * Position in SUBTILE space in a world, each unit represents a single subtile.
+ * This is divided by the size of the tile, e.g. if a tile is 16x16 then there
+ * are 256 / tile size = units per pixel of a tile. This means there are always
+ * uint8_t max subtiles in a tile.
+ */
+typedef uint8_t worldsubtile_t;
+
+/**
+ * Position in TILE space in a world, each unit represents a single tile. This
+ * is within CHUNK space. This is not different depending on chunk size, if the
+ * chunks are 32 tiles wide then the max tile value is 31.
+ */
+typedef uint8_t worldtile_t;
+
+/**
+ * Represents a position in a world in SUBTILE and TILE space. This is basically
+ * just a convenience struct so you don't have to pass two variables around.
+ * 
+ * For example, an entity may be at tile (2, 3) and subtile (8, 12).
+ * meaning that the entity is at pixel (2 * TILE_SIZE + 8, 3 * TILE_SIZE + 12)
+ * in world space.
+ * 
+ * This is still within CHUNK space.
+ */
+typedef struct worldchunkpos_s {
+  worldsubtile_t subtile;
+  worldtile_t tile;
+} worldchunkpos_t;
+
+/**
+ * Position in CHUNK space in a world, each unit represents a single chunk.
+ */
+typedef uint8_t worldchunk_t;
+
+/**
+ * Represents a position in a world in SUBTILE, TILE and CHUNK space. This is in
+ * WORLD space, so this is the full position of an entity in the world.
+ */
+typedef struct worldpos_s {
+  worldsubtile_t subtile;
+  worldtile_t tile;
+  worldchunk_t chunk;
+} worldpos_t;