Smooth out acceleration and braking

2 files changed, 32 insertions, 17 deletions

diff --git a/TODO.org b/TODO.org
index 7f4497a..4a4bbda 100644
--- a/TODO.org
+++ b/TODO.org
@@ -9,7 +9,7 @@
 ** DONE Detect collision with other vehicles
 ** DONE Make cars in different lanes drive at different speeds
 ** DONE Add restart option
-** TODO Smooth acceleration
+** DONE Smooth acceleration
 ** TODO Smooth increasing turn rate
 ** TODO Display level on screen
 ** TODO Add weapon to player car
@@ -19,4 +19,4 @@
 ** TODO Improve visuals
 ** TODO Add start menu
 ** DONE Add music
-** TODO Add sound effects
+** STARTED Add sound effects
diff --git a/turbo.scm b/turbo.scm
index 63ebe0a..4af0b6b 100644
--- a/turbo.scm
+++ b/turbo.scm
@@ -27,9 +27,14 @@
 (define vehicles-sprites (load-tileset "vehicles.png" vehicle-length vehicle-height))
 
 (define player-velocity (vec2 0 0))
-(define player-min-speed 4)
-(define player-max-speed 20)
+(define player-min-speed 250)
+(define player-max-speed 2000)
 (define player-rotation 0)
+;; 2px/s/s acceleration
+(define player-car-acceleration 100)
+;; 4px/s/s deceleration
+(define player-car-deceleration -500)
+(define player-current-acceleration 0)
 
 (define level-difficulty 1)
 
@@ -63,7 +68,7 @@
   (let ((lane-num (random road-num-lanes)))
     (set-vehicle-position! veh (calculate-vehicle-position
 				(+ 1 lane-num)))
-    (set-vehicle-speed! veh (+ player-min-speed lane-num) )
+    (set-vehicle-speed! veh (+ player-min-speed (* 25 lane-num)) )
     (set-vehicle-active! veh #f)))
 
 (define vehicles (make-vehicle-list (list) 0))
@@ -165,7 +170,7 @@
 
 (define (vehicle-off-screen? veh)
   (and vehicle-active?
-       (>= (- 0 vehicle-length) (vec2-x (vehicle-position veh)))))
+       (>= (- vehicle-length) (vec2-x (vehicle-position veh)))))
 
 ;;;; Chickadee hooks
 
@@ -184,6 +189,12 @@
 	      (off-road-player)
 	      (set! game-over #t)))
 
+	(let ((new-speed (+ (vehicle-speed player-car)
+			    (* player-current-acceleration interval))))
+	  (set-vehicle-speed! player-car (min player-max-speed
+					      (max player-min-speed
+						   new-speed))))
+
 	(if (player-collides?)
 	    (begin
 	      (off-road-player)
@@ -191,14 +202,15 @@
 	      (set! game-over #t)))
 
 	(set! road-section-position
-	      (if (< road-section-position (- 0 lane-length))
-		  (- (+ road-section-position lane-length) (vehicle-speed player-car))
-		  (- road-section-position (vehicle-speed player-car))))
+	      (if (< road-section-position (- lane-length))
+		  (- (+ road-section-position lane-length) (* interval (vehicle-speed player-car)))
+		  (- road-section-position (* interval (vehicle-speed player-car)))))
 
-	(set-vehicle-position! player-car (vec2+ (vehicle-position player-car) player-velocity))
+	(set-vehicle-position! player-car (vec2+ (vehicle-position player-car)
+						 player-velocity))
 
 	(for-each (lambda (veh)
-		    (vehicle-move! veh (vec2 (- 0 (vehicle-speed- player-car veh)) 0)))
+		    (vehicle-move! veh (vec2 (- (* interval (vehicle-speed- player-car veh))) 0)))
 		  (filter vehicle-active? vehicles))
 
 	;; Reset vehicles that have gone off screen
@@ -230,8 +242,8 @@
 	      (draw-sprite (vehicle-sprite veh) (vehicle-position veh)))
 	    (filter vehicle-active? vehicles))
 
-  (draw-text (format #f "Speed: ~smph" (* (vehicle-speed player-car) 5))
-	     (vec2 450.0 20.0)
+  (draw-text (format #f "Speed: ~smph" (round (* (vehicle-speed player-car) 0.11187)))
+	     (vec2 400.0 20.0)
 	     #:font the-font
 	     #:scale (vec2 2 2))
   
@@ -246,11 +258,11 @@
    ((eq? key 'w)
     (set! player-velocity (vec2 0 vehicle-steering-speed)))
    ((eq? key 's)
-    (set! player-velocity (vec2 0 (- 0 vehicle-steering-speed))))
-   ((eq? key 'a)
-    (set-player-speed! (- (vehicle-speed player-car) 1)))
+    (set! player-velocity (vec2 0 (- vehicle-steering-speed))))
    ((eq? key 'd)
-    (set-player-speed! (+ (vehicle-speed player-car) 1)))
+    (set! player-current-acceleration player-car-acceleration))
+   ((eq? key 'a)
+    (set! player-current-acceleration player-car-deceleration))
    ((eq? key 'escape)
        (abort-game))
    ((and (eq? key 'return) game-over)
@@ -263,5 +275,8 @@
     (set! game-over #f))))
 
 (define (key-release key modifiers)
+  (cond
+   ((or (eq? key 'a) (eq? key 'd))
+    (set! player-current-acceleration 0)))
   (if (or (eq? key 'w) (eq? key 's))
       (set! player-velocity (vec2 0 0))))