fix chunk loading based on player position

src/dusk/rpg/rpgcamera.c

@@ -45,13 +45,16 @@ errorret_t rpgCameraUpdate(void) {
 
   vec3 pos;
   rpgCameraGetPosition(pos);
-  worldpos_t worldPos = {
+
-    (worldunit_t)pos[0],
+  // Round to the nearest chunk center rather than flooring, so the
-    (worldunit_t)pos[1],
+  // loaded window is always most centered on what the camera sees.
-    (worldunit_t)pos[2]
+  // Adding half the chunk dimension before flooring snaps at the
+  // midpoint of each chunk instead of at the boundary.
+  chunkpos_t chunkPos = {
+    .x = (chunkunit_t)floorf(pos[0] / CHUNK_WIDTH + 0.5f),
+    .y = (chunkunit_t)floorf(pos[1] / CHUNK_HEIGHT + 0.5f),
+    .z = (chunkunit_t)floorf(pos[2] / CHUNK_DEPTH + 0.5f)
   };
-  chunkpos_t chunkPos;
-  worldPosToChunkPos(&worldPos, &chunkPos);
 
   errorChain(mapPositionSet((chunkpos_t){
     .x = chunkPos.x - (MAP_CHUNK_WIDTH / 2),