add parallax background

- scaled assets to 960x540 and adjusted window for that size
- adjusted ground level
- collect background and foreground actions in functions
- tuned physics

TODO.org

@@ -4,7 +4,7 @@
 A flappy bird clone to get experience with Common Lisp and game development.
 
 
-* Game Plan [7/15]
+* Game Plan [8/15]
 - [X] Create bird, well, ball
 - [X] Add physics for ball movement
 - [X] Add inputs on key and mouse clicks
@@ -12,7 +12,7 @@ A flappy bird clone to get experience with Common Lisp and game development.
 - [X] Scroll pipes
 - [X] Detect collisions
 - [X] Add regression tests
-- [ ] Add background
+- [X] Add background
 - [ ] Create random pipes 
 - [ ] Add goal after last pipe
 - [ ] Create state machine to manage start/play/finish

flappy-ball.lisp

@@ -93,33 +93,54 @@
 
 ;; -------------------------------------------------------------
 
+(defun draw_image_layer(resource scroll-x)
+  (let ((pic (load-resource resource))
+        (offset (mod scroll-x 960))
+        )
+    (draw (crop pic offset 0 960 540) 
+          :x 0 :y 0 :width 960 :height 540)))
+
+
+(defun draw_background (scroll-x)
+  (draw_image_layer "assets/level1/sky.png" 0)
+  (draw_image_layer "assets/level1/clouds.png" (* -0.15 scroll-x))
+  (draw_image_layer "assets/level1/far.png" (* 0.25 scroll-x))
+  (draw_image_layer "assets/level1/middle.png" (* 0.6 scroll-x)))
+
+(defun draw_foreground (pipes scroll-x pipe-pen height)
+  (dolist (pipe pipes)
+    (pipe-draw pipe pipe-pen scroll-x height))
+  (draw_image_layer "assets/level1/ground.png" scroll-x))
+
 (defsketch flappy-ball
     ((title "Flappy Ball")
-     (width 800)
+     (width 960)
-     (height 600)
+     (height 540)
+     (ground-level 440)
      (copy-pixels nil)
      (ball (make-ball (/ width 10) (/ height 3) 0 10))
-     (gravity 0.05)
+     (gravity 0.025)
-     (flap-speed -2.5)
+     (flap-speed -1)
      (ball-pen (make-pen :stroke (gray 0.5) :fill sketch:+yellow+ :weight 1))
      (collision-pen (make-pen :stroke (gray 0.5) :fill sketch:+red+ :weight 1))
      (pipe-pen (make-pen :stroke (gray 0.5) :fill sketch:+green+ :weight 1))
      (pipes (list
-             (make-pipe 200 200 100 20)
+             (make-pipe 200 100 100 20)
-             (make-pipe 400 300 100 20)
+             (make-pipe 400 200 100 20)
-             (make-pipe 600 400 100 20)))
+             (make-pipe 600 300 100 20)))
      (scroll-x 0.0)
      (scroll-speed 0.2))
 
-  (dolist (pipe pipes)
+  (draw_background scroll-x)
-    (pipe-draw pipe pipe-pen scroll-x height))
+  (draw_foreground pipes scroll-x pipe-pen height)
+  
   (ball-draw ball
              (if (some (lambda (pipe) (pipe-collides pipe ball scroll-x)) pipes)
                  collision-pen
                  ball-pen))
   
   (setf scroll-x (+ scroll-x scroll-speed))
-  (setf ball (ball-move ball gravity height)))
+  (setf ball (ball-move ball gravity ground-level)))
 
 (defmethod on-click ((instance flappy-ball) x y)
   (with-slots (ball flap-speed) instance