Work on demos

1 files changed, 3 insertions, 3 deletions

diff --git a/docs/guide.org b/docs/guide.org
index de07c82..380f04b 100644
--- a/docs/guide.org
+++ b/docs/guide.org
@@ -125,7 +125,7 @@ csc square.scm -o square
 
 Press arrow keys to move the yellow square around. Here are the key ideas:
 
-- **Scenes**: =make-scene= creates a container for entities, tilemaps, and the camera. It holds the game state each frame.
+- **Scenes**: =make-scene= creates a container for entities, tilemaps, and the camera. It holds the game state each frame. Optional =background:= ~(r g b)~ or ~(r g b a)~ sets the color used to clear the window each frame (default is black).
 - **Entities**: Entities are plists (property lists). They have no class; they're pure data. Access properties with =entity-ref=, and update with =entity-set= (which returns a *new* plist — always bind the result).
 - **Input**: =input-held?= returns =#t= if an action is currently pressed. Actions are symbols like ='left=, ='right=, ='up=, ='down= (from the default input config).
 - **Update & Render**: The =update:= hook runs first and updates entities. The =render:= hook runs after the default rendering pipeline and is used for custom drawing like this colored rectangle.
@@ -193,7 +193,7 @@ For a real game, you probably want tilemaps, gravity, and collision detection. D
              (player (resolve-tile-collisions-x player tm))
              (player (apply-velocity-y   player))
              (player (resolve-tile-collisions-y player tm))
-             (player (detect-ground      player tm)))
+             (player (detect-on-solid   player tm)))
         ;; Update camera to follow player
         (let ((cam-x (max 0 (- (entity-ref player #:x 0) 300))))
           (camera-x-set! (scene-camera scene) cam-x))
@@ -210,7 +210,7 @@ Key points:
 - **=play-sound=** plays a loaded sound effect.
 - **Physics pipeline**: Functions like =apply-gravity=, =apply-velocity-x=, =resolve-tile-collisions-x= form the physics pipeline. Apply them in order each frame to get correct platformer behavior.
 - **Tile collisions**: =resolve-tile-collisions-x= and =resolve-tile-collisions-y= snap entities to tile edges, preventing clipping.
-- **Ground detection**: =detect-ground= sets the =#:on-ground?= flag so you know if a jump is valid.
+- **On-solid check**: =detect-on-solid= sets the =#:on-ground?= flag from tiles below the feet and, if you pass other scene entities, from standing on solids (moving platforms, crates). Call it after collisions; use the flag next frame to gate jumps. (Despite the =?=-suffix, it returns an updated entity, not a boolean.)
 
 See =demo/platformer.scm= in the engine source for a complete working example.