Add active camera and clear-background documentation

README.org

@@ -140,18 +140,24 @@ Create a new render queue in ~render-queues~, where ~queue-name~ is the queue na
 Adds a thunk to the given render queue name at the given layer. ~queue-name~ must be a symbol, ~layer~ must be an integer, and ~thunk~ must be a zero-argument procedure. 
 
 #+begin_src scheme
-  (evaluate-render-queue queue-name mode)
+  *active-camera-2d*
-  (perform-render)
+  *active-camera-3d*
 #+end_src
-Functions for evaluating the render queues. ~evaluate-render-queue~ evaluates a single queue where ~queue-name~ is a symbol corresponding to a queue in the ~render-queues~, and ~mode~ is a drawing mode symbol (either ~screen~, ~2d~, or ~3d~). The given queue is cleared after evaluation.
+Parameters which describe the currently active camera for 2D and 3D drawing.
-
-~perform-render~ iterates the ~render-priority~ association list and calls ~evaluate-render-queue~ on each queue in order with the appropriate mode.
 
 #+begin_src scheme
   *clear-color*
 #+end_src
 ~*clear-color*~ is a parameter which expects a u8vector corresponding to a Raylib color.
 
+#+begin_src scheme
+  (evaluate-render-queue queue-name mode)
+  (perform-render)
+#+end_src
+Functions for evaluating the render queues. ~evaluate-render-queue~ evaluates a single queue where ~queue-name~ is a symbol corresponding to a queue in the ~render-queues~, and ~mode~ is a drawing mode symbol (either ~screen~, ~2d~, or ~3d~). The given queue is cleared after evaluation, and each thunk in the render queue is evaluated with the appropriate mode, using the ~*active-camera-2d*~ and ~*active-camera-3d*~ for the ~2d~ and ~3d~ drawing modes.
+
+~perform-render~ clears the screen to the set ~*clear-color*~, then iterates the ~render-priority~ association list and calls ~evaluate-render-queue~ on each queue in order with the appropriate mode.
+
 #+begin_src scheme
   (resolve-queues)
 #+end_src