Fix little speed difference bugs

3 files changed, 20 insertions, 12 deletions

diff --git a/TODO.org b/TODO.org
index 7f4497a..8cac592 100644
--- a/TODO.org
+++ b/TODO.org
@@ -8,7 +8,7 @@
 *** DONE Ensure vehicles don't overlap
 ** DONE Detect collision with other vehicles
 ** DONE Make cars in different lanes drive at different speeds
-** DONE Add restart option
+** TODO Add restart option
 ** TODO Smooth acceleration
 ** TODO Smooth increasing turn rate
 ** TODO Display level on screen
diff --git a/turbo.scm b/turbo.scm
index 92c5103..1c32f01 100644
--- a/turbo.scm
+++ b/turbo.scm
@@ -31,7 +31,7 @@
 (define player-max-speed 20)
 (define player-rotation 0)
 
-(define level-difficulty 50)
+(define level-difficulty 1)
 
 (define music-play? #t)
 (define music-res (load-audio "music.ogg"))
@@ -77,9 +77,9 @@
 
 (define (vehicle-has-spawn-space? vehicle)
   (define (vehicle-in-the-way? v)
-    (and (not (= (vehicle-id vehicle) (vehicle-id v)))
-	 (vehicle-inactive? v)
-	 (vehicle-safety-distance? v vehicle)))
+    (and (not (vehicle= vehicle v))
+	 (vehicle-active? v)
+	 (not (vehicle-safety-distance? v vehicle))))
   (not (any vehicle-in-the-way? vehicles)))
 
 
@@ -198,18 +198,22 @@
 	(set-vehicle-position! player-car (vec2+ (vehicle-position player-car) player-velocity))
 
 	(for-each (lambda (veh)
-		    (vehicle-move! veh (vec2 (- 0 (vehicle-speed-diff player-car veh)) 0)))
+		    (vehicle-move! veh (vec2 (- 0 (vehicle-speed- player-car veh)) 0)))
 		  (filter vehicle-active? vehicles))
 
-	;; when vehicle goes off screen
+	;; Reset vehicles that have gone off screen
 	(for-each vehicle-reset-ahead (filter vehicle-off-screen? vehicles))
 
+	;; Randomly respawn vehicles based on level difficulty
 	(if (= 0 (random level-difficulty))
 	    (begin
 	      (let* ((inactive-vehicles (filter vehicle-inactive? vehicles))
 		     (spawnable-vehicles (filter vehicle-has-spawn-space? inactive-vehicles)))
 		(if (not (null? spawnable-vehicles))
-		    (set-vehicle-active! (car spawnable-vehicles) #t)))))
+		    (set-vehicle-active! (list-ref
+					  spawnable-vehicles
+					  (random (length spawnable-vehicles)))
+					 #t)))))
 	;; End begin
 	)))
 
diff --git a/turbo/vehicles.scm b/turbo/vehicles.scm
index 68d6ced..940011e 100644
--- a/turbo/vehicles.scm
+++ b/turbo/vehicles.scm
@@ -18,8 +18,9 @@
 	    set-vehicle-active!
 	    vehicle-hitbox
 	    vehicle-safety-distance?
-	    vehicle-speed-diff
-	    vehicle-move!))
+	    vehicle-speed-
+	    vehicle-move!
+	    vehicle=))
 
 (define vehicle-height 45)
 (define vehicle-length 100)
@@ -49,8 +50,8 @@
     (> (abs (- vehicle2-x vehicle1-x))
        (+ (* 3 vehicle-length)))))
 
-(define (vehicle-speed-diff vehicle1 vehicle2)
-  (abs (- (vehicle-speed vehicle1) (vehicle-speed vehicle2))))
+(define (vehicle-speed- vehicle1 vehicle2)
+  (- (vehicle-speed vehicle1) (vehicle-speed vehicle2)))
 
 (define (vehicle-move! vehicle translation)
   (set-vehicle-position!
@@ -59,3 +60,6 @@
 
 (define (vehicle-inactive? vehicle)
   (not (vehicle-active? vehicle)))
+
+(define (vehicle= vehicle1 vehicle2)
+  (= (vehicle-id vehicle1) (vehicle-id vehicle2)))