From 9e998d7ea8b7401199ec77df78024de8699474d0 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Sun, 26 Aug 2018 20:12:04 -0400
Subject: Animate sprite based on elapsed program time, not agenda time.

---
 Makefile.am          |  4 ++--
 starling/kernel.scm  | 10 ++++++++--
 starling/node-2d.scm |  5 +++--
 3 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/Makefile.am b/Makefile.am
index 108173a..7a12ef2 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -41,9 +41,9 @@ SOURCES = 					\
   starling/inotify.scm				\
   starling/asset.scm				\
   starling/node.scm				\
-  starling/node-2d.scm				\
   starling/repl.scm				\
-  starling/kernel.scm
+  starling/kernel.scm				\
+  starling/node-2d.scm
 
 EXTRA_DIST += 					\
   COPYING
diff --git a/starling/kernel.scm b/starling/kernel.scm
index 9c23448..04fb4cd 100644
--- a/starling/kernel.scm
+++ b/starling/kernel.scm
@@ -52,18 +52,21 @@
             on-controller-press
             on-controller-release
             on-controller-move
+
             <window-config>
             width
             height
             title
             fullscreen?
+
             <kernel>
             window-config
             update-hz
             window
             gl-context
             current-kernel
-            boot-kernel)
+            boot-kernel
+            elapsed-time)
   #:re-export (abort-game))
 
 ;; Input event handler methods
@@ -262,6 +265,9 @@
         (set-window-title! (window kernel) title))
       (apply throw key args)))
 
+(define (elapsed-time)
+  (sdl-ticks))
+
 (define (boot-kernel kernel first-node)
   (sdl-init)
   ;; This will throw an error if any audio subsystem is unavailable,
@@ -298,7 +304,7 @@
                     #:render (lambda (alpha) (render* kernel alpha))
                     #:error (lambda (stack key args)
                               (on-error kernel stack key args))
-                    #:time sdl-ticks
+                    #:time elapsed-time
                     #:update-hz (update-hz kernel))))
       (lambda ()
         (deactivate kernel)
diff --git a/starling/node-2d.scm b/starling/node-2d.scm
index 39a5aa7..7867fe1 100644
--- a/starling/node-2d.scm
+++ b/starling/node-2d.scm
@@ -35,6 +35,7 @@
   #:use-module (chickadee scripting)
   #:use-module (oop goops)
   #:use-module (starling asset)
+  #:use-module (starling kernel)
   #:use-module (starling node)
   #:export (<camera-2d>
             target
@@ -368,7 +369,7 @@
   (let* ((anim (assq-ref (animations sprite) (current-animation sprite)))
          (frame-duration (frame-duration sprite))
          (anim-duration (* frame-duration (vector-length anim)))
-         (time (modulo (- (agenda-time) (start-time sprite)) anim-duration))
+         (time (modulo (- (elapsed-time) (start-time sprite)) anim-duration))
          (frame (vector-ref anim (floor (/ time frame-duration))))
          (texture-region (texture-atlas-ref (asset-ref (atlas sprite)) frame)))
     (set! (texture sprite) texture-region)
@@ -376,7 +377,7 @@
 
 (define-method (change-animation (sprite <animated-sprite>) name)
   (set! (current-animation sprite) name)
-  (set! (start-time sprite) (with-agenda (agenda sprite) (agenda-time))))
+  (set! (start-time sprite) (elapsed-time)))
 
 
 ;;;
-- 
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