[Plib-cvs] plib/src/sg sg.cxx,1.34,1.35 sg.h,1.36,1.37

[Steve B. <sj...@us...>]

Update of /cvsroot/plib/plib/src/sg
In directory usw-pr-cvs1:/tmp/cvs-serv29374/plib/src/sg

Modified Files:
	sg.cxx sg.h 
Log Message:
Added a simple Spring/Mass/Damper model to SG.


Index: sg.cxx
===================================================================
RCS file: /cvsroot/plib/plib/src/sg/sg.cxx,v
retrieving revision 1.34
retrieving revision 1.35
diff -u -d -r1.34 -r1.35
--- sg.cxx	14 Jun 2002 04:38:23 -0000	1.34
+++ sg.cxx	11 Aug 2002 14:07:09 -0000	1.35
@@ -24,6 +24,8 @@
 
 #include "sg.h"
 
+sgVec3 _sgGravity = { 0.0f, 0.0f, -9.8f } ;
+
 void sgVectorProductVec3 ( sgVec3 dst, const sgVec3 a, const sgVec3 b )
 {
   dst[0] = a[1] * b[2] - a[2] * b[1] ;

Index: sg.h
===================================================================
RCS file: /cvsroot/plib/plib/src/sg/sg.h,v
retrieving revision 1.36
retrieving revision 1.37
diff -u -d -r1.36 -r1.37
--- sg.h	14 Jun 2002 04:38:23 -0000	1.36
+++ sg.h	11 Aug 2002 14:07:09 -0000	1.37
@@ -2642,5 +2642,139 @@
 void sgdTriangleSolver_SAAtoASS(SGDfloat  lenA,SGDfloat  angB,SGDfloat  angA,
                                 SGDfloat *angC,SGDfloat *lenB,SGDfloat *lenC ) ;
 
+/*
+  SPRING-MASS-DAMPER (with simple Euler integrator)
+*/
+
+
+extern sgVec3 _sgGravity ;
+
+void   sgSetGravity     ( float  g ) { sgSetVec3 ( _sgGravity, 0.0f, 0.0f, -g ) ; }
[...108 lines suppressed...]
+  void update ()
+  {
+    sgVec3 dP ; sgSubVec3 ( dP, p0->getPos(), p1->getPos() ) ;
+    sgVec3 dV ; sgSubVec3 ( dV, p0->getVel(), p1->getVel() ) ;
+
+    float  L = sgLengthVec3 ( dP ) ; if ( L == 0.0f ) L = 0.0000001 ;
+    float  H = ( L - restLength ) * stiffness ;
+    float  D = sgScalarProductVec3 ( dV, dP ) * damping / L ;
+
+    sgVec3 F ; sgScaleVec3 ( dP, - ( H + D ) / L ) ;
+
+    p0 -> addForce ( F ) ;
+    p1 -> addForce ( F ) ;
+  }
+
+} ;
+
+
 #endif