From ecece3590dc1bf91e10c13facccbd283c58fc535 Mon Sep 17 00:00:00 2001
From: Dan Ballard <dan@mindstab.net>
Date: Sat, 13 Aug 2011 12:09:25 -0700
Subject: [PATCH] forward motion just needs debugging

---
 engine.lisp     | 18 +++---------------
 flight-sim.lisp |  6 ++++--
 objects.lisp    | 14 +++++++++++++-
 3 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/engine.lisp b/engine.lisp
index 44b244f..4a2a01e 100644
--- a/engine.lisp
+++ b/engine.lisp
@@ -50,24 +50,12 @@
   (call-next-method))
 	    
       
-(defmethod phys-act ((src engine-object) (target game-object) time)
-  (let* ((scalar-proj (scalar-proj (vector-scale-1 (direction (force (src)))) (vector-scale-1 (position src))))
+(defmethod get-accel ((src engine-object) (target game-object))
+  (let* ((scalar-proj (scalar-proj (scale-vector-1 (direction (force (body src)))) (scale-vector-1 (coords (body src)))))
 	 (accel (/ (newtons (force src)) (mass (body target))))
 	 (accel-vec (scale-vector scalar-proj accel)))
+    accel-vec))
     
-
-
-; time is time elapsed in seconds (with decimal for sub seconds)
-;(defmethod time-step ((engine engine) object time)
-;  ; f = ma
-;  (let ((accel (/ (force engine) (mass object)))) 
-;  ; x = x +v*t + 1/2 * a * t^2
-;  (dotimes (i 3) (progn
-;                  (incf (aref (coords motion) i) 
-;                        (+ (* (aref (velocity motion) i) time) (* .5 (aref (acceleration motion) i) (expt time 2))))
-;                  (incf (aref (velocity motion) i)
-;                        (* time (aref (acceleration motion) i))))))
-
     
     
 
diff --git a/flight-sim.lisp b/flight-sim.lisp
index c64e56a..bd688b8 100644
--- a/flight-sim.lisp
+++ b/flight-sim.lisp
@@ -103,8 +103,10 @@
     (otherwise (format t "~a~%" key))))
 
 (defun phys-step (time)
-  (loop for sym in (active-attachments *self*) do
-       (phys-act (getf (attachments *self*) sym) *self*  time)))
+  (let ((accel (vector 0 0 0)))
+    (loop for sym in (active-attachments *self*) do
+	 (setf accel (vector+ accel (get-accel (getf (attachments *self*) sym) *self*))))
+    (apply-accel *self* accel time)))
 
 
 (defun sim-step ()
diff --git a/objects.lisp b/objects.lisp
index bc9f8b6..7117f4b 100644
--- a/objects.lisp
+++ b/objects.lisp
@@ -40,5 +40,17 @@
   (loop for a in (active-attachments object) do
        (draw (getf (attachments object) a) time)))
 
+;; get the vector of accel src object exerts on target object
+(defgeneric get-accel (src target))
+
+(defgeneric apply-accel (object accel time))
+
+; time is time elapsed in seconds (with decimal for sub seconds)
+(defmethod apply-accel ((object game-object) accel time)
+  ; x = x +v*t + 1/2 * a * t^2
+  (dotimes (i 3) (progn
+                  (incf (aref (coords (body object)) i) 
+                        (+ (* (aref (velocity (body object)) i) time) (* .5 (aref accel i) (expt time 2))))
+                  (incf (aref (velocity (body object)) i)
+                        (* time (aref accel i))))))
 
-(defgeneric phys-act (src target time))
\ No newline at end of file