from the start... checking in ode-0.9

1 files changed, 1732 insertions, 0 deletions

diff --git a/libraries/ode-0.9/ode/src/ode.cpp b/libraries/ode-0.9/ode/src/ode.cpp
new file mode 100644
index 0000000..46f559a
--- /dev/null
+++ b/libraries/ode-0.9/ode/src/ode.cpp
@@ -0,0 +1,1732 @@
+/*************************************************************************
+ *                                                                       *
+ * Open Dynamics Engine, Copyright (C) 2001,2002 Russell L. Smith.       *
+ * All rights reserved.  Email: russ@q12.org   Web: www.q12.org          *
+ *                                                                       *
+ * This library is free software; you can redistribute it and/or         *
+ * modify it under the terms of EITHER:                                  *
+ *   (1) The GNU Lesser General Public License as published by the Free  *
+ *       Software Foundation; either version 2.1 of the License, or (at  *
+ *       your option) any later version. The text of the GNU Lesser      *
+ *       General Public License is included with this library in the     *
+ *       file LICENSE.TXT.                                               *
+ *   (2) The BSD-style license that is included with this library in     *
+ *       the file LICENSE-BSD.TXT.                                       *
+ *                                                                       *
+ * This library is distributed in the hope that it will be useful,       *
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the files    *
+ * LICENSE.TXT and LICENSE-BSD.TXT for more details.                     *
+ *                                                                       *
+ *************************************************************************/
+
+#ifdef _MSC_VER
+#pragma warning(disable:4291)  // for VC++, no complaints about "no matching operator delete found"
+#endif
+
+// this source file is mostly concerned with the data structures, not the
+// numerics.
+
+#include "objects.h"
+#include <ode/ode.h>
+#include "joint.h"
+#include <ode/odemath.h>
+#include <ode/matrix.h>
+#include "step.h"
+#include "quickstep.h"
+#include "util.h"
+#include <ode/memory.h>
+#include <ode/error.h>
+
+// misc defines
+#define ALLOCA dALLOCA16
+
+//****************************************************************************
+// utility
+
+static inline void initObject (dObject *obj, dxWorld *w)
+{
+  obj->world = w;
+  obj->next = 0;
+  obj->tome = 0;
+  obj->userdata = 0;
+  obj->tag = 0;
+}
+
+
+// add an object `obj' to the list who's head pointer is pointed to by `first'.
+
+static inline void addObjectToList (dObject *obj, dObject **first)
+{
+  obj->next = *first;
+  obj->tome = first;
+  if (*first) (*first)->tome = &obj->next;
+  (*first) = obj;
+}
+
+
+// remove the object from the linked list
+
+static inline void removeObjectFromList (dObject *obj)
+{
+  if (obj->next) obj->next->tome = obj->tome;
+  *(obj->tome) = obj->next;
+  // safeguard
+  obj->next = 0;
+  obj->tome = 0;
+}
+
+
+// remove the joint from neighbour lists of all connected bodies
+
+static void removeJointReferencesFromAttachedBodies (dxJoint *j)
+{
+  for (int i=0; i<2; i++) {
+    dxBody *body = j->node[i].body;
+    if (body) {
+      dxJointNode *n = body->firstjoint;
+      dxJointNode *last = 0;
+      while (n) {
+        if (n->joint == j) {
+          if (last) last->next = n->next;
+          else body->firstjoint = n->next;
+          break;
+        }
+        last = n;
+        n = n->next;
+      }
+    }
+  }
+  j->node[0].body = 0;
+  j->node[0].next = 0;
+  j->node[1].body = 0;
+  j->node[1].next = 0;
+}
+
+//****************************************************************************
+// debugging
+
+// see if an object list loops on itself (if so, it's bad).
+
+static int listHasLoops (dObject *first)
+{
+  if (first==0 || first->next==0) return 0;
+  dObject *a=first,*b=first->next;
+  int skip=0;
+  while (b) {
+    if (a==b) return 1;
+    b = b->next;
+    if (skip) a = a->next;
+    skip ^= 1;
+  }
+  return 0;
+}
+
+
+// check the validity of the world data structures
+
+static void checkWorld (dxWorld *w)
+{
+  dxBody *b;
+  dxJoint *j;
+
+  // check there are no loops
+  if (listHasLoops (w->firstbody)) dDebug (0,"body list has loops");
+  if (listHasLoops (w->firstjoint)) dDebug (0,"joint list has loops");
+
+  // check lists are well formed (check `tome' pointers)
+  for (b=w->firstbody; b; b=(dxBody*)b->next) {
+    if (b->next && b->next->tome != &b->next)
+      dDebug (0,"bad tome pointer in body list");
+  }
+  for (j=w->firstjoint; j; j=(dxJoint*)j->next) {
+    if (j->next && j->next->tome != &j->next)
+      dDebug (0,"bad tome pointer in joint list");
+  }
+
+  // check counts
+  int n = 0;
+  for (b=w->firstbody; b; b=(dxBody*)b->next) n++;
+  if (w->nb != n) dDebug (0,"body count incorrect");
+  n = 0;
+  for (j=w->firstjoint; j; j=(dxJoint*)j->next) n++;
+  if (w->nj != n) dDebug (0,"joint count incorrect");
+
+  // set all tag values to a known value
+  static int count = 0;
+  count++;
+  for (b=w->firstbody; b; b=(dxBody*)b->next) b->tag = count;
+  for (j=w->firstjoint; j; j=(dxJoint*)j->next) j->tag = count;
+
+  // check all body/joint world pointers are ok
+  for (b=w->firstbody; b; b=(dxBody*)b->next) if (b->world != w)
+    dDebug (0,"bad world pointer in body list");
+  for (j=w->firstjoint; j; j=(dxJoint*)j->next) if (j->world != w)
+    dDebug (0,"bad world pointer in joint list");
+
+  /*
+  // check for half-connected joints - actually now these are valid
+  for (j=w->firstjoint; j; j=(dxJoint*)j->next) {
+    if (j->node[0].body || j->node[1].body) {
+      if (!(j->node[0].body && j->node[1].body))
+        dDebug (0,"half connected joint found");
+    }
+  }
+  */
+
+  // check that every joint node appears in the joint lists of both bodies it
+  // attaches
+  for (j=w->firstjoint; j; j=(dxJoint*)j->next) {
+    for (int i=0; i<2; i++) {
+      if (j->node[i].body) {
+        int ok = 0;
+        for (dxJointNode *n=j->node[i].body->firstjoint; n; n=n->next) {
+          if (n->joint == j) ok = 1;
+        }
+        if (ok==0) dDebug (0,"joint not in joint list of attached body");
+      }
+    }
+  }
+
+  // check all body joint lists (correct body ptrs)
+  for (b=w->firstbody; b; b=(dxBody*)b->next) {
+    for (dxJointNode *n=b->firstjoint; n; n=n->next) {
+      if (&n->joint->node[0] == n) {
+        if (n->joint->node[1].body != b)
+          dDebug (0,"bad body pointer in joint node of body list (1)");
+      }
+      else {
+        if (n->joint->node[0].body != b)
+          dDebug (0,"bad body pointer in joint node of body list (2)");
+      }
+      if (n->joint->tag != count) dDebug (0,"bad joint node pointer in body");
+    }
+  }
+
+  // check all body pointers in joints, check they are distinct
+  for (j=w->firstjoint; j; j=(dxJoint*)j->next) {
+    if (j->node[0].body && (j->node[0].body == j->node[1].body))
+      dDebug (0,"non-distinct body pointers in joint");
+    if ((j->node[0].body && j->node[0].body->tag != count) ||
+        (j->node[1].body && j->node[1].body->tag != count))
+      dDebug (0,"bad body pointer in joint");
+  }
+}
+
+
+void dWorldCheck (dxWorld *w)
+{
+  checkWorld (w);
+}
+
+//****************************************************************************
+// body
+dxWorld* dBodyGetWorld (dxBody* b)
+{
+  dAASSERT (b);
+  return b->world;
+}
+
+dxBody *dBodyCreate (dxWorld *w)
+{
+  dAASSERT (w);
+  dxBody *b = new dxBody;
+  initObject (b,w);
+  b->firstjoint = 0;
+  b->flags = 0;
+  b->geom = 0;
+  b->average_lvel_buffer = 0;
+  b->average_avel_buffer = 0;
+  dMassSetParameters (&b->mass,1,0,0,0,1,1,1,0,0,0);
+  dSetZero (b->invI,4*3);
+  b->invI[0] = 1;
+  b->invI[5] = 1;
+  b->invI[10] = 1;
+  b->invMass = 1;
+  dSetZero (b->posr.pos,4);
+  dSetZero (b->q,4);
+  b->q[0] = 1;
+  dRSetIdentity (b->posr.R);
+  dSetZero (b->lvel,4);
+  dSetZero (b->avel,4);
+  dSetZero (b->facc,4);
+  dSetZero (b->tacc,4);
+  dSetZero (b->finite_rot_axis,4);
+  addObjectToList (b,(dObject **) &w->firstbody);
+  w->nb++;
+
+  // set auto-disable parameters
+  b->average_avel_buffer = b->average_lvel_buffer = 0; // no buffer at beginnin
+  dBodySetAutoDisableDefaults (b);      // must do this after adding to world
+  b->adis_stepsleft = b->adis.idle_steps;
+  b->adis_timeleft = b->adis.idle_time;
+  b->average_counter = 0;
+  b->average_ready = 0; // average buffer not filled on the beginning
+  dBodySetAutoDisableAverageSamplesCount(b, b->adis.average_samples);
+
+  return b;
+}
+
+
+void dBodyDestroy (dxBody *b)
+{
+  dAASSERT (b);
+
+  // all geoms that link to this body must be notified that the body is about
+  // to disappear. note that the call to dGeomSetBody(geom,0) will result in
+  // dGeomGetBodyNext() returning 0 for the body, so we must get the next body
+  // before setting the body to 0.
+  dxGeom *next_geom = 0;
+  for (dxGeom *geom = b->geom; geom; geom = next_geom) {
+    next_geom = dGeomGetBodyNext (geom);
+    dGeomSetBody (geom,0);
+  }
+
+  // detach all neighbouring joints, then delete this body.
+  dxJointNode *n = b->firstjoint;
+  while (n) {
+    // sneaky trick to speed up removal of joint references (black magic)
+    n->joint->node[(n == n->joint->node)].body = 0;
+
+    dxJointNode *next = n->next;
+    n->next = 0;
+    removeJointReferencesFromAttachedBodies (n->joint);
+    n = next;
+  }
+  removeObjectFromList (b);
+  b->world->nb--;
+
+  // delete the average buffers
+  if(b->average_lvel_buffer)
+  {
+          delete[] (b->average_lvel_buffer);
+          b->average_lvel_buffer = 0;
+  }
+  if(b->average_avel_buffer)
+  {
+          delete[] (b->average_avel_buffer);
+          b->average_avel_buffer = 0;
+  }
+
+  delete b;
+}
+
+
+void dBodySetData (dBodyID b, void *data)
+{
+  dAASSERT (b);
+  b->userdata = data;
+}
+
+
+void *dBodyGetData (dBodyID b)
+{
+  dAASSERT (b);
+  return b->userdata;
+}
+
+
+void dBodySetPosition (dBodyID b, dReal x, dReal y, dReal z)
+{
+  dAASSERT (b);
+  b->posr.pos[0] = x;
+  b->posr.pos[1] = y;
+  b->posr.pos[2] = z;
+
+  // notify all attached geoms that this body has moved
+  for (dxGeom *geom = b->geom; geom; geom = dGeomGetBodyNext (geom))
+    dGeomMoved (geom);
+}
+
+
+void dBodySetRotation (dBodyID b, const dMatrix3 R)
+{
+  dAASSERT (b && R);
+  dQuaternion q;
+  dRtoQ (R,q);
+  dNormalize4 (q);
+  b->q[0] = q[0];
+  b->q[1] = q[1];
+  b->q[2] = q[2];
+  b->q[3] = q[3];
+  dQtoR (b->q,b->posr.R);
+
+  // notify all attached geoms that this body has moved
+  for (dxGeom *geom = b->geom; geom; geom = dGeomGetBodyNext (geom))
+    dGeomMoved (geom);
+}
+
+
+void dBodySetQuaternion (dBodyID b, const dQuaternion q)
+{
+  dAASSERT (b && q);
+  b->q[0] = q[0];
+  b->q[1] = q[1];
+  b->q[2] = q[2];
+  b->q[3] = q[3];
+  dNormalize4 (b->q);
+  dQtoR (b->q,b->posr.R);
+
+  // notify all attached geoms that this body has moved
+  for (dxGeom *geom = b->geom; geom; geom = dGeomGetBodyNext (geom))
+    dGeomMoved (geom);
+}
+
+
+void dBodySetLinearVel  (dBodyID b, dReal x, dReal y, dReal z)
+{
+  dAASSERT (b);
+  b->lvel[0] = x;
+  b->lvel[1] = y;
+  b->lvel[2] = z;
+}
+
+
+void dBodySetAngularVel (dBodyID b, dReal x, dReal y, dReal z)
+{
+  dAASSERT (b);
+  b->avel[0] = x;
+  b->avel[1] = y;
+  b->avel[2] = z;
+}
+
+
+const dReal * dBodyGetPosition (dBodyID b)
+{
+  dAASSERT (b);
+  return b->posr.pos;
+}
+
+
+void dBodyCopyPosition (dBodyID b, dVector3 pos)
+{
+        dAASSERT (b);
+        dReal* src = b->posr.pos;
+        pos[0] = src[0];
+        pos[1] = src[1];
+        pos[2] = src[2];
+}
+
+
+const dReal * dBodyGetRotation (dBodyID b)
+{
+  dAASSERT (b);
+  return b->posr.R;
+}
+
+
+void dBodyCopyRotation (dBodyID b, dMatrix3 R)
+{
+        dAASSERT (b);
+        const dReal* src = b->posr.R;
+        R[0] = src[0];
+        R[1] = src[1];
+        R[2] = src[2];
+        R[3] = src[3];
+        R[4] = src[4];
+        R[5] = src[5];
+        R[6] = src[6];
+        R[7] = src[7];
+        R[8] = src[8];
+        R[9] = src[9];
+        R[10] = src[10];
+        R[11] = src[11];
+}
+
+
+const dReal * dBodyGetQuaternion (dBodyID b)
+{
+  dAASSERT (b);
+  return b->q;
+}
+
+
+void dBodyCopyQuaternion (dBodyID b, dQuaternion quat)
+{
+        dAASSERT (b);
+        dReal* src = b->q;
+        quat[0] = src[0];
+        quat[1] = src[1];
+        quat[2] = src[2];
+        quat[3] = src[3];
+}
+
+
+const dReal * dBodyGetLinearVel (dBodyID b)
+{
+  dAASSERT (b);
+  return b->lvel;
+}
+
+
+const dReal * dBodyGetAngularVel (dBodyID b)
+{
+  dAASSERT (b);
+  return b->avel;
+}
+
+
+void dBodySetMass (dBodyID b, const dMass *mass)
+{
+  dAASSERT (b && mass );
+  dIASSERT(dMassCheck(mass));
+
+  // The centre of mass must be at the origin.
+  // Use dMassTranslate( mass, -mass->c[0], -mass->c[1], -mass->c[2] ) to correct it.
+  dUASSERT( fabs( mass->c[0] ) <= dEpsilon &&
+                        fabs( mass->c[1] ) <= dEpsilon &&
+                        fabs( mass->c[2] ) <= dEpsilon, "The centre of mass must be at the origin." )
+
+  memcpy (&b->mass,mass,sizeof(dMass));
+  if (dInvertPDMatrix (b->mass.I,b->invI,3)==0) {
+    dDEBUGMSG ("inertia must be positive definite!");
+    dRSetIdentity (b->invI);
+  }
+  b->invMass = dRecip(b->mass.mass);
+}
+
+
+void dBodyGetMass (dBodyID b, dMass *mass)
+{
+  dAASSERT (b && mass);
+  memcpy (mass,&b->mass,sizeof(dMass));
+}
+
+
+void dBodyAddForce (dBodyID b, dReal fx, dReal fy, dReal fz)
+{
+  dAASSERT (b);
+  b->facc[0] += fx;
+  b->facc[1] += fy;
+  b->facc[2] += fz;
+}
+
+
+void dBodyAddTorque (dBodyID b, dReal fx, dReal fy, dReal fz)
+{
+  dAASSERT (b);
+  b->tacc[0] += fx;
+  b->tacc[1] += fy;
+  b->tacc[2] += fz;
+}
+
+
+void dBodyAddRelForce (dBodyID b, dReal fx, dReal fy, dReal fz)
+{
+  dAASSERT (b);
+  dVector3 t1,t2;
+  t1[0] = fx;
+  t1[1] = fy;
+  t1[2] = fz;
+  t1[3] = 0;
+  dMULTIPLY0_331 (t2,b->posr.R,t1);
+  b->facc[0] += t2[0];
+  b->facc[1] += t2[1];
+  b->facc[2] += t2[2];
+}
+
+
+void dBodyAddRelTorque (dBodyID b, dReal fx, dReal fy, dReal fz)
+{
+  dAASSERT (b);
+  dVector3 t1,t2;
+  t1[0] = fx;
+  t1[1] = fy;
+  t1[2] = fz;
+  t1[3] = 0;
+  dMULTIPLY0_331 (t2,b->posr.R,t1);
+  b->tacc[0] += t2[0];
+  b->tacc[1] += t2[1];
+  b->tacc[2] += t2[2];
+}
+
+
+void dBodyAddForceAtPos (dBodyID b, dReal fx, dReal fy, dReal fz,
+                         dReal px, dReal py, dReal pz)
+{
+  dAASSERT (b);
+  b->facc[0] += fx;
+  b->facc[1] += fy;
+  b->facc[2] += fz;
+  dVector3 f,q;
+  f[0] = fx;
+  f[1] = fy;
+  f[2] = fz;
+  q[0] = px - b->posr.pos[0];
+  q[1] = py - b->posr.pos[1];
+  q[2] = pz - b->posr.pos[2];
+  dCROSS (b->tacc,+=,q,f);
+}
+
+
+void dBodyAddForceAtRelPos (dBodyID b, dReal fx, dReal fy, dReal fz,
+                            dReal px, dReal py, dReal pz)
+{
+  dAASSERT (b);
+  dVector3 prel,f,p;
+  f[0] = fx;
+  f[1] = fy;
+  f[2] = fz;
+  f[3] = 0;
+  prel[0] = px;
+  prel[1] = py;
+  prel[2] = pz;
+  prel[3] = 0;
+  dMULTIPLY0_331 (p,b->posr.R,prel);
+  b->facc[0] += f[0];
+  b->facc[1] += f[1];
+  b->facc[2] += f[2];
+  dCROSS (b->tacc,+=,p,f);
+}
+
+
+void dBodyAddRelForceAtPos (dBodyID b, dReal fx, dReal fy, dReal fz,
+                            dReal px, dReal py, dReal pz)
+{
+  dAASSERT (b);
+  dVector3 frel,f;
+  frel[0] = fx;
+  frel[1] = fy;
+  frel[2] = fz;
+  frel[3] = 0;
+  dMULTIPLY0_331 (f,b->posr.R,frel);
+  b->facc[0] += f[0];
+  b->facc[1] += f[1];
+  b->facc[2] += f[2];
+  dVector3 q;
+  q[0] = px - b->posr.pos[0];
+  q[1] = py - b->posr.pos[1];
+  q[2] = pz - b->posr.pos[2];
+  dCROSS (b->tacc,+=,q,f);
+}
+
+
+void dBodyAddRelForceAtRelPos (dBodyID b, dReal fx, dReal fy, dReal fz,
+                               dReal px, dReal py, dReal pz)
+{
+  dAASSERT (b);
+  dVector3 frel,prel,f,p;
+  frel[0] = fx;
+  frel[1] = fy;
+  frel[2] = fz;
+  frel[3] = 0;
+  prel[0] = px;
+  prel[1] = py;
+  prel[2] = pz;
+  prel[3] = 0;
+  dMULTIPLY0_331 (f,b->posr.R,frel);
+  dMULTIPLY0_331 (p,b->posr.R,prel);
+  b->facc[0] += f[0];
+  b->facc[1] += f[1];
+  b->facc[2] += f[2];
+  dCROSS (b->tacc,+=,p,f);
+}
+
+
+const dReal * dBodyGetForce (dBodyID b)
+{
+  dAASSERT (b);
+  return b->facc;
+}
+
+
+const dReal * dBodyGetTorque (dBodyID b)
+{
+  dAASSERT (b);
+  return b->tacc;
+}
+
+
+void dBodySetForce (dBodyID b, dReal x, dReal y, dReal z)
+{
+  dAASSERT (b);
+  b->facc[0] = x;
+  b->facc[1] = y;
+  b->facc[2] = z;
+}
+
+
+void dBodySetTorque (dBodyID b, dReal x, dReal y, dReal z)
+{
+  dAASSERT (b);
+  b->tacc[0] = x;
+  b->tacc[1] = y;
+  b->tacc[2] = z;
+}
+
+
+void dBodyGetRelPointPos (dBodyID b, dReal px, dReal py, dReal pz,
+                          dVector3 result)
+{
+  dAASSERT (b);
+  dVector3 prel,p;
+  prel[0] = px;
+  prel[1] = py;
+  prel[2] = pz;
+  prel[3] = 0;
+  dMULTIPLY0_331 (p,b->posr.R,prel);
+  result[0] = p[0] + b->posr.pos[0];
+  result[1] = p[1] + b->posr.pos[1];
+  result[2] = p[2] + b->posr.pos[2];
+}
+
+
+void dBodyGetRelPointVel (dBodyID b, dReal px, dReal py, dReal pz,
+                          dVector3 result)
+{
+  dAASSERT (b);
+  dVector3 prel,p;
+  prel[0] = px;
+  prel[1] = py;
+  prel[2] = pz;
+  prel[3] = 0;
+  dMULTIPLY0_331 (p,b->posr.R,prel);
+  result[0] = b->lvel[0];
+  result[1] = b->lvel[1];
+  result[2] = b->lvel[2];
+  dCROSS (result,+=,b->avel,p);
+}
+
+
+void dBodyGetPointVel (dBodyID b, dReal px, dReal py, dReal pz,
+                       dVector3 result)
+{
+  dAASSERT (b);
+  dVector3 p;
+  p[0] = px - b->posr.pos[0];
+  p[1] = py - b->posr.pos[1];
+  p[2] = pz - b->posr.pos[2];
+  p[3] = 0;
+  result[0] = b->lvel[0];
+  result[1] = b->lvel[1];
+  result[2] = b->lvel[2];
+  dCROSS (result,+=,b->avel,p);
+}
+
+
+void dBodyGetPosRelPoint (dBodyID b, dReal px, dReal py, dReal pz,
+                          dVector3 result)
+{
+  dAASSERT (b);
+  dVector3 prel;
+  prel[0] = px - b->posr.pos[0];
+  prel[1] = py - b->posr.pos[1];
+  prel[2] = pz - b->posr.pos[2];
+  prel[3] = 0;
+  dMULTIPLY1_331 (result,b->posr.R,prel);
+}
+
+
+void dBodyVectorToWorld (dBodyID b, dReal px, dReal py, dReal pz,
+                         dVector3 result)
+{
+  dAASSERT (b);
+  dVector3 p;
+  p[0] = px;
+  p[1] = py;
+  p[2] = pz;
+  p[3] = 0;
+  dMULTIPLY0_331 (result,b->posr.R,p);
+}
+
+
+void dBodyVectorFromWorld (dBodyID b, dReal px, dReal py, dReal pz,
+                           dVector3 result)
+{
+  dAASSERT (b);
+  dVector3 p;
+  p[0] = px;
+  p[1] = py;
+  p[2] = pz;
+  p[3] = 0;
+  dMULTIPLY1_331 (result,b->posr.R,p);
+}
+
+
+void dBodySetFiniteRotationMode (dBodyID b, int mode)
+{
+  dAASSERT (b);
+  b->flags &= ~(dxBodyFlagFiniteRotation | dxBodyFlagFiniteRotationAxis);
+  if (mode) {
+    b->flags |= dxBodyFlagFiniteRotation;
+    if (b->finite_rot_axis[0] != 0 || b->finite_rot_axis[1] != 0 ||
+        b->finite_rot_axis[2] != 0) {
+      b->flags |= dxBodyFlagFiniteRotationAxis;
+    }
+  }
+}
+
+
+void dBodySetFiniteRotationAxis (dBodyID b, dReal x, dReal y, dReal z)
+{
+  dAASSERT (b);
+  b->finite_rot_axis[0] = x;
+  b->finite_rot_axis[1] = y;
+  b->finite_rot_axis[2] = z;
+  if (x != 0 || y != 0 || z != 0) {
+    dNormalize3 (b->finite_rot_axis);
+    b->flags |= dxBodyFlagFiniteRotationAxis;
+  }
+  else {
+    b->flags &= ~dxBodyFlagFiniteRotationAxis;
+  }
+}
+
+
+int dBodyGetFiniteRotationMode (dBodyID b)
+{
+  dAASSERT (b);
+  return ((b->flags & dxBodyFlagFiniteRotation) != 0);
+}
+
+
+void dBodyGetFiniteRotationAxis (dBodyID b, dVector3 result)
+{
+  dAASSERT (b);
+  result[0] = b->finite_rot_axis[0];
+  result[1] = b->finite_rot_axis[1];
+  result[2] = b->finite_rot_axis[2];
+}
+
+
+int dBodyGetNumJoints (dBodyID b)
+{
+  dAASSERT (b);
+  int count=0;
+  for (dxJointNode *n=b->firstjoint; n; n=n->next, count++);
+  return count;
+}
+
+
+dJointID dBodyGetJoint (dBodyID b, int index)
+{
+  dAASSERT (b);
+  int i=0;
+  for (dxJointNode *n=b->firstjoint; n; n=n->next, i++) {
+    if (i == index) return n->joint;
+  }
+  return 0;
+}
+
+
+void dBodyEnable (dBodyID b)
+{
+  dAASSERT (b);
+  b->flags &= ~dxBodyDisabled;
+  b->adis_stepsleft = b->adis.idle_steps;
+  b->adis_timeleft = b->adis.idle_time;
+  // no code for average-processing needed here
+}
+
+
+void dBodyDisable (dBodyID b)
+{
+  dAASSERT (b);
+  b->flags |= dxBodyDisabled;
+}
+
+
+int dBodyIsEnabled (dBodyID b)
+{
+  dAASSERT (b);
+  return ((b->flags & dxBodyDisabled) == 0);
+}
+
+
+void dBodySetGravityMode (dBodyID b, int mode)
+{
+  dAASSERT (b);
+  if (mode) b->flags &= ~dxBodyNoGravity;
+  else b->flags |= dxBodyNoGravity;
+}
+
+
+int dBodyGetGravityMode (dBodyID b)
+{
+  dAASSERT (b);
+  return ((b->flags & dxBodyNoGravity) == 0);
+}
+
+
+// body auto-disable functions
+
+dReal dBodyGetAutoDisableLinearThreshold (dBodyID b)
+{
+        dAASSERT(b);
+        return dSqrt (b->adis.linear_average_threshold);
+}
+
+
+void dBodySetAutoDisableLinearThreshold (dBodyID b, dReal linear_average_threshold)
+{
+        dAASSERT(b);
+        b->adis.linear_average_threshold = linear_average_threshold * linear_average_threshold;
+}
+
+
+dReal dBodyGetAutoDisableAngularThreshold (dBodyID b)
+{
+        dAASSERT(b);
+        return dSqrt (b->adis.angular_average_threshold);
+}
+
+
+void dBodySetAutoDisableAngularThreshold (dBodyID b, dReal angular_average_threshold)
+{
+        dAASSERT(b);
+        b->adis.angular_average_threshold = angular_average_threshold * angular_average_threshold;
+}
+
+
+int dBodyGetAutoDisableAverageSamplesCount (dBodyID b)
+{
+        dAASSERT(b);
+        return b->adis.average_samples;
+}
+
+
+void dBodySetAutoDisableAverageSamplesCount (dBodyID b, unsigned int average_samples_count)
+{
+        dAASSERT(b);
+        b->adis.average_samples = average_samples_count;
+        // update the average buffers
+        if(b->average_lvel_buffer)
+        {
+                delete[] b->average_lvel_buffer;
+                b->average_lvel_buffer = 0;
+        }
+        if(b->average_avel_buffer)
+        {
+                delete[] b->average_avel_buffer;
+                b->average_avel_buffer = 0;
+        }
+        if(b->adis.average_samples > 0)
+        {
+                b->average_lvel_buffer = new dVector3[b->adis.average_samples];
+                b->average_avel_buffer = new dVector3[b->adis.average_samples];
+        }
+        else
+        {
+                b->average_lvel_buffer = 0;
+                b->average_avel_buffer = 0;
+        }
+        // new buffer is empty
+        b->average_counter = 0;
+        b->average_ready = 0;
+}
+
+
+int dBodyGetAutoDisableSteps (dBodyID b)
+{
+        dAASSERT(b);
+        return b->adis.idle_steps;
+}
+
+
+void dBodySetAutoDisableSteps (dBodyID b, int steps)
+{
+        dAASSERT(b);
+        b->adis.idle_steps = steps;
+}
+
+
+dReal dBodyGetAutoDisableTime (dBodyID b)
+{
+        dAASSERT(b);
+        return b->adis.idle_time;
+}
+
+
+void dBodySetAutoDisableTime (dBodyID b, dReal time)
+{
+        dAASSERT(b);
+        b->adis.idle_time = time;
+}
+
+
+int dBodyGetAutoDisableFlag (dBodyID b)
+{
+        dAASSERT(b);
+        return ((b->flags & dxBodyAutoDisable) != 0);
+}
+
+
+void dBodySetAutoDisableFlag (dBodyID b, int do_auto_disable)
+{
+        dAASSERT(b);
+        if (!do_auto_disable)
+        {
+                b->flags &= ~dxBodyAutoDisable;
+                // (mg) we should also reset the IsDisabled state to correspond to the DoDisabling flag
+                b->flags &= ~dxBodyDisabled;
+                b->adis.idle_steps = dWorldGetAutoDisableSteps(b->world);
+                b->adis.idle_time = dWorldGetAutoDisableTime(b->world);
+                // resetting the average calculations too
+                dBodySetAutoDisableAverageSamplesCount(b, dWorldGetAutoDisableAverageSamplesCount(b->world) );
+        }
+        else
+        {
+                b->flags |= dxBodyAutoDisable;
+        }
+}
+
+
+void dBodySetAutoDisableDefaults (dBodyID b)
+{
+        dAASSERT(b);
+        dWorldID w = b->world;
+        dAASSERT(w);
+        b->adis = w->adis;
+        dBodySetAutoDisableFlag (b, w->adis_flag);
+}
+
+//****************************************************************************
+// joints
+
+static void dJointInit (dxWorld *w, dxJoint *j)
+{
+  dIASSERT (w && j);
+  initObject (j,w);
+  j->vtable = 0;
+  j->flags = 0;
+  j->node[0].joint = j;
+  j->node[0].body = 0;
+  j->node[0].next = 0;
+  j->node[1].joint = j;
+  j->node[1].body = 0;
+  j->node[1].next = 0;
+  dSetZero (j->lambda,6);
+  addObjectToList (j,(dObject **) &w->firstjoint);
+  w->nj++;
+}
+
+
+static dxJoint *createJoint (dWorldID w, dJointGroupID group,
+                             dxJoint::Vtable *vtable)
+{
+  dIASSERT (w && vtable);
+  dxJoint *j;
+  if (group) {
+    j = (dxJoint*) group->stack.alloc (vtable->size);
+    group->num++;
+  }
+  else j = (dxJoint*) dAlloc (vtable->size);
+  dJointInit (w,j);
+  j->vtable = vtable;
+  if (group) j->flags |= dJOINT_INGROUP;
+  if (vtable->init) vtable->init (j);
+  j->feedback = 0;
+  return j;
+}
+
+
+dxJoint * dJointCreateBall (dWorldID w, dJointGroupID group)
+{
+  dAASSERT (w);
+  return createJoint (w,group,&__dball_vtable);
+}
+
+
+dxJoint * dJointCreateHinge (dWorldID w, dJointGroupID group)
+{
+  dAASSERT (w);
+  return createJoint (w,group,&__dhinge_vtable);
+}
+
+
+dxJoint * dJointCreateSlider (dWorldID w, dJointGroupID group)
+{
+  dAASSERT (w);
+  return createJoint (w,group,&__dslider_vtable);
+}
+
+
+dxJoint * dJointCreateContact (dWorldID w, dJointGroupID group,
+                               const dContact *c)
+{
+  dAASSERT (w && c);
+  dxJointContact *j = (dxJointContact *)
+    createJoint (w,group,&__dcontact_vtable);
+  j->contact = *c;
+  return j;
+}
+
+
+dxJoint * dJointCreateHinge2 (dWorldID w, dJointGroupID group)
+{
+  dAASSERT (w);
+  return createJoint (w,group,&__dhinge2_vtable);
+}
+
+
+dxJoint * dJointCreateUniversal (dWorldID w, dJointGroupID group)
+{
+  dAASSERT (w);
+  return createJoint (w,group,&__duniversal_vtable);
+}
+
+dxJoint * dJointCreatePR (dWorldID w, dJointGroupID group)
+{
+  dAASSERT (w);
+  return createJoint (w,group,&__dPR_vtable);
+}
+
+dxJoint * dJointCreateFixed (dWorldID w, dJointGroupID group)
+{
+  dAASSERT (w);
+  return createJoint (w,group,&__dfixed_vtable);
+}
+
+
+dxJoint * dJointCreateNull (dWorldID w, dJointGroupID group)
+{
+  dAASSERT (w);
+  return createJoint (w,group,&__dnull_vtable);
+}
+
+
+dxJoint * dJointCreateAMotor (dWorldID w, dJointGroupID group)
+{
+  dAASSERT (w);
+  return createJoint (w,group,&__damotor_vtable);
+}
+
+dxJoint * dJointCreateLMotor (dWorldID w, dJointGroupID group)
+{
+  dAASSERT (w);
+  return createJoint (w,group,&__dlmotor_vtable);
+}
+
+dxJoint * dJointCreatePlane2D (dWorldID w, dJointGroupID group)
+{
+  dAASSERT (w);
+  return createJoint (w,group,&__dplane2d_vtable);
+}
+
+void dJointDestroy (dxJoint *j)
+{
+  dAASSERT (j);
+  if (j->flags & dJOINT_INGROUP) return;
+  removeJointReferencesFromAttachedBodies (j);
+  removeObjectFromList (j);
+  j->world->nj--;
+  dFree (j,j->vtable->size);
+}
+
+
+dJointGroupID dJointGroupCreate (int max_size)
+{
+  // not any more ... dUASSERT (max_size > 0,"max size must be > 0");
+  dxJointGroup *group = new dxJointGroup;
+  group->num = 0;
+  return group;
+}
+
+
+void dJointGroupDestroy (dJointGroupID group)
+{
+  dAASSERT (group);
+  dJointGroupEmpty (group);
+  delete group;
+}
+
+
+void dJointGroupEmpty (dJointGroupID group)
+{
+  // the joints in this group are detached starting from the most recently
+  // added (at the top of the stack). this helps ensure that the various
+  // linked lists are not traversed too much, as the joints will hopefully
+  // be at the start of those lists.
+  // if any group joints have their world pointer set to 0, their world was
+  // previously destroyed. no special handling is required for these joints.
+
+  dAASSERT (group);
+  int i;
+  dxJoint **jlist = (dxJoint**) ALLOCA (group->num * sizeof(dxJoint*));
+  dxJoint *j = (dxJoint*) group->stack.rewind();
+  for (i=0; i < group->num; i++) {
+    jlist[i] = j;
+    j = (dxJoint*) (group->stack.next (j->vtable->size));
+  }
+  for (i=group->num-1; i >= 0; i--) {
+    if (jlist[i]->world) {
+      removeJointReferencesFromAttachedBodies (jlist[i]);
+      removeObjectFromList (jlist[i]);
+      jlist[i]->world->nj--;
+    }
+  }
+  group->num = 0;
+  group->stack.freeAll();
+}
+
+
+void dJointAttach (dxJoint *joint, dxBody *body1, dxBody *body2)
+{
+  // check arguments
+  dUASSERT (joint,"bad joint argument");
+  dUASSERT (body1 == 0 || body1 != body2,"can't have body1==body2");
+  dxWorld *world = joint->world;
+  dUASSERT ( (!body1 || body1->world == world) &&
+             (!body2 || body2->world == world),
+             "joint and bodies must be in same world");
+
+  // check if the joint can not be attached to just one body
+  dUASSERT (!((joint->flags & dJOINT_TWOBODIES) &&
+              ((body1 != 0) ^ (body2 != 0))),
+            "joint can not be attached to just one body");
+
+  // remove any existing body attachments
+  if (joint->node[0].body || joint->node[1].body) {
+    removeJointReferencesFromAttachedBodies (joint);
+  }
+
+  // if a body is zero, make sure that it is body2, so 0 --> node[1].body
+  if (body1==0) {
+    body1 = body2;
+    body2 = 0;
+    joint->flags |= dJOINT_REVERSE;
+  }
+  else {
+    joint->flags &= (~dJOINT_REVERSE);
+  }
+
+  // attach to new bodies
+  joint->node[0].body = body1;
+  joint->node[1].body = body2;
+  if (body1) {
+    joint->node[1].next = body1->firstjoint;
+    body1->firstjoint = &joint->node[1];
+  }
+  else joint->node[1].next = 0;
+  if (body2) {
+    joint->node[0].next = body2->firstjoint;
+    body2->firstjoint = &joint->node[0];
+  }
+  else {
+    joint->node[0].next = 0;
+  }
+}
+
+
+void dJointSetData (dxJoint *joint, void *data)
+{
+  dAASSERT (joint);
+  joint->userdata = data;
+}
+
+
+void *dJointGetData (dxJoint *joint)
+{
+  dAASSERT (joint);
+  return joint->userdata;
+}
+
+
+int dJointGetType (dxJoint *joint)
+{
+  dAASSERT (joint);
+  return joint->vtable->typenum;
+}
+
+
+dBodyID dJointGetBody (dxJoint *joint, int index)
+{
+  dAASSERT (joint);
+  if (index == 0 || index == 1) {
+    if (joint->flags & dJOINT_REVERSE) return joint->node[1-index].body;
+    else return joint->node[index].body;
+  }
+  else return 0;
+}
+
+
+void dJointSetFeedback (dxJoint *joint, dJointFeedback *f)
+{
+  dAASSERT (joint);
+  joint->feedback = f;
+}
+
+
+dJointFeedback *dJointGetFeedback (dxJoint *joint)
+{
+  dAASSERT (joint);
+  return joint->feedback;
+}
+
+
+
+dJointID dConnectingJoint (dBodyID in_b1, dBodyID in_b2)
+{
+    dAASSERT (in_b1 || in_b2);
+
+        dBodyID b1, b2;
+
+        if (in_b1 == 0) {
+                b1 = in_b2;
+                b2 = in_b1;
+        }
+        else {
+                b1 = in_b1;
+                b2 = in_b2;
+        }
+
+    // look through b1's neighbour list for b2
+    for (dxJointNode *n=b1->firstjoint; n; n=n->next) {
+        if (n->body == b2) return n->joint;
+    }
+
+    return 0;
+}
+
+
+
+int dConnectingJointList (dBodyID in_b1, dBodyID in_b2, dJointID* out_list)
+{
+    dAASSERT (in_b1 || in_b2);
+
+
+        dBodyID b1, b2;
+
+        if (in_b1 == 0) {
+                b1 = in_b2;
+                b2 = in_b1;
+        }
+        else {
+                b1 = in_b1;
+                b2 = in_b2;
+        }
+
+    // look through b1's neighbour list for b2
+    int numConnectingJoints = 0;
+    for (dxJointNode *n=b1->firstjoint; n; n=n->next) {
+        if (n->body == b2)
+            out_list[numConnectingJoints++] = n->joint;
+    }
+
+    return numConnectingJoints;
+}
+
+
+int dAreConnected (dBodyID b1, dBodyID b2)
+{
+  dAASSERT (b1 && b2);
+  // look through b1's neighbour list for b2
+  for (dxJointNode *n=b1->firstjoint; n; n=n->next) {
+    if (n->body == b2) return 1;
+  }
+  return 0;
+}
+
+
+int dAreConnectedExcluding (dBodyID b1, dBodyID b2, int joint_type)
+{
+  dAASSERT (b1 && b2);
+  // look through b1's neighbour list for b2
+  for (dxJointNode *n=b1->firstjoint; n; n=n->next) {
+    if (dJointGetType (n->joint) != joint_type && n->body == b2) return 1;
+  }
+  return 0;
+}
+
+//****************************************************************************
+// world
+
+dxWorld * dWorldCreate()
+{
+  dxWorld *w = new dxWorld;
+  w->firstbody = 0;
+  w->firstjoint = 0;
+  w->nb = 0;
+  w->nj = 0;
+  dSetZero (w->gravity,4);
+  w->global_erp = REAL(0.2);
+#if defined(dSINGLE)
+  w->global_cfm = 1e-5f;
+#elif defined(dDOUBLE)
+  w->global_cfm = 1e-10;
+#else
+  #error dSINGLE or dDOUBLE must be defined
+#endif
+
+  w->adis.idle_steps = 10;
+  w->adis.idle_time = 0;
+  w->adis_flag = 0;
+  w->adis.average_samples = 1;          // Default is 1 sample => Instantaneous velocity
+  w->adis.angular_average_threshold = REAL(0.01)*REAL(0.01);    // (magnitude squared)
+  w->adis.linear_average_threshold = REAL(0.01)*REAL(0.01);             // (magnitude squared)
+
+  w->qs.num_iterations = 20;
+  w->qs.w = REAL(1.3);
+
+  w->contactp.max_vel = dInfinity;
+  w->contactp.min_depth = 0;
+
+  return w;
+}
+
+
+void dWorldDestroy (dxWorld *w)
+{
+  // delete all bodies and joints
+  dAASSERT (w);
+  dxBody *nextb, *b = w->firstbody;
+  while (b) {
+    nextb = (dxBody*) b->next;
+    if(b->average_lvel_buffer)
+    {
+      delete[] (b->average_lvel_buffer);
+      b->average_lvel_buffer = 0;
+    }
+    if(b->average_avel_buffer)
+    {
+      delete[] (b->average_avel_buffer);
+      b->average_avel_buffer = 0;
+    }
+    dBodyDestroy(b); // calling here dBodyDestroy for correct destroying! (i.e. the average buffers)
+    b = nextb;
+  }
+  dxJoint *nextj, *j = w->firstjoint;
+  while (j) {
+    nextj = (dxJoint*)j->next;
+    if (j->flags & dJOINT_INGROUP) {
+      // the joint is part of a group, so "deactivate" it instead
+      j->world = 0;
+      j->node[0].body = 0;
+      j->node[0].next = 0;
+      j->node[1].body = 0;
+      j->node[1].next = 0;
+      dMessage (0,"warning: destroying world containing grouped joints");
+    }
+    else {
+      dFree (j,j->vtable->size);
+    }
+    j = nextj;
+  }
+  delete w;
+}
+
+
+void dWorldSetGravity (dWorldID w, dReal x, dReal y, dReal z)
+{
+  dAASSERT (w);
+  w->gravity[0] = x;
+  w->gravity[1] = y;
+  w->gravity[2] = z;
+}
+
+
+void dWorldGetGravity (dWorldID w, dVector3 g)
+{
+  dAASSERT (w);
+  g[0] = w->gravity[0];
+  g[1] = w->gravity[1];
+  g[2] = w->gravity[2];
+}
+
+
+void dWorldSetERP (dWorldID w, dReal erp)
+{
+  dAASSERT (w);
+  w->global_erp = erp;
+}
+
+
+dReal dWorldGetERP (dWorldID w)
+{
+  dAASSERT (w);
+  return w->global_erp;
+}
+
+
+void dWorldSetCFM (dWorldID w, dReal cfm)
+{
+  dAASSERT (w);
+  w->global_cfm = cfm;
+}
+
+
+dReal dWorldGetCFM (dWorldID w)
+{
+  dAASSERT (w);
+  return w->global_cfm;
+}
+
+
+void dWorldStep (dWorldID w, dReal stepsize)
+{
+  dUASSERT (w,"bad world argument");
+  dUASSERT (stepsize > 0,"stepsize must be > 0");
+  dxProcessIslands (w,stepsize,&dInternalStepIsland);
+}
+
+
+void dWorldQuickStep (dWorldID w, dReal stepsize)
+{
+  dUASSERT (w,"bad world argument");
+  dUASSERT (stepsize > 0,"stepsize must be > 0");
+  dxProcessIslands (w,stepsize,&dxQuickStepper);
+}
+
+
+void dWorldImpulseToForce (dWorldID w, dReal stepsize,
+                           dReal ix, dReal iy, dReal iz,
+                           dVector3 force)
+{
+  dAASSERT (w);
+  stepsize = dRecip(stepsize);
+  force[0] = stepsize * ix;
+  force[1] = stepsize * iy;
+  force[2] = stepsize * iz;
+  // @@@ force[3] = 0;
+}
+
+
+// world auto-disable functions
+
+dReal dWorldGetAutoDisableLinearThreshold (dWorldID w)
+{
+        dAASSERT(w);
+        return dSqrt (w->adis.linear_average_threshold);
+}
+
+
+void dWorldSetAutoDisableLinearThreshold (dWorldID w, dReal linear_average_threshold)
+{
+        dAASSERT(w);
+        w->adis.linear_average_threshold = linear_average_threshold * linear_average_threshold;
+}
+
+
+dReal dWorldGetAutoDisableAngularThreshold (dWorldID w)
+{
+        dAASSERT(w);
+        return dSqrt (w->adis.angular_average_threshold);
+}
+
+
+void dWorldSetAutoDisableAngularThreshold (dWorldID w, dReal angular_average_threshold)
+{
+        dAASSERT(w);
+        w->adis.angular_average_threshold = angular_average_threshold * angular_average_threshold;
+}
+
+
+int dWorldGetAutoDisableAverageSamplesCount (dWorldID w)
+{
+        dAASSERT(w);
+        return w->adis.average_samples;
+}
+
+
+void dWorldSetAutoDisableAverageSamplesCount (dWorldID w, unsigned int average_samples_count)
+{
+        dAASSERT(w);
+        w->adis.average_samples = average_samples_count;
+}
+
+
+int dWorldGetAutoDisableSteps (dWorldID w)
+{
+        dAASSERT(w);
+        return w->adis.idle_steps;
+}
+
+
+void dWorldSetAutoDisableSteps (dWorldID w, int steps)
+{
+        dAASSERT(w);
+        w->adis.idle_steps = steps;
+}
+
+
+dReal dWorldGetAutoDisableTime (dWorldID w)
+{
+        dAASSERT(w);
+        return w->adis.idle_time;
+}
+
+
+void dWorldSetAutoDisableTime (dWorldID w, dReal time)
+{
+        dAASSERT(w);
+        w->adis.idle_time = time;
+}
+
+
+int dWorldGetAutoDisableFlag (dWorldID w)
+{
+        dAASSERT(w);
+        return w->adis_flag;
+}
+
+
+void dWorldSetAutoDisableFlag (dWorldID w, int do_auto_disable)
+{
+        dAASSERT(w);
+        w->adis_flag = (do_auto_disable != 0);
+}
+
+
+void dWorldSetQuickStepNumIterations (dWorldID w, int num)
+{
+        dAASSERT(w);
+        w->qs.num_iterations = num;
+}
+
+
+int dWorldGetQuickStepNumIterations (dWorldID w)
+{
+        dAASSERT(w);
+        return w->qs.num_iterations;
+}
+
+
+void dWorldSetQuickStepW (dWorldID w, dReal param)
+{
+        dAASSERT(w);
+        w->qs.w = param;
+}
+
+
+dReal dWorldGetQuickStepW (dWorldID w)
+{
+        dAASSERT(w);
+        return w->qs.w;
+}
+
+
+void dWorldSetContactMaxCorrectingVel (dWorldID w, dReal vel)
+{
+        dAASSERT(w);
+        w->contactp.max_vel = vel;
+}
+
+
+dReal dWorldGetContactMaxCorrectingVel (dWorldID w)
+{
+        dAASSERT(w);
+        return w->contactp.max_vel;
+}
+
+
+void dWorldSetContactSurfaceLayer (dWorldID w, dReal depth)
+{
+        dAASSERT(w);
+        w->contactp.min_depth = depth;
+}
+
+
+dReal dWorldGetContactSurfaceLayer (dWorldID w)
+{
+        dAASSERT(w);
+        return w->contactp.min_depth;
+}
+
+//****************************************************************************
+// testing
+
+#define NUM 100
+
+#define DO(x)
+
+
+extern "C" void dTestDataStructures()
+{
+  int i;
+  DO(printf ("testDynamicsStuff()\n"));
+
+  dBodyID body [NUM];
+  int nb = 0;
+  dJointID joint [NUM];
+  int nj = 0;
+
+  for (i=0; i<NUM; i++) body[i] = 0;
+  for (i=0; i<NUM; i++) joint[i] = 0;
+
+  DO(printf ("creating world\n"));
+  dWorldID w = dWorldCreate();
+  checkWorld (w);
+
+  for (;;) {
+    if (nb < NUM && dRandReal() > 0.5) {
+      DO(printf ("creating body\n"));
+      body[nb] = dBodyCreate (w);
+      DO(printf ("\t--> %p\n",body[nb]));
+      nb++;
+      checkWorld (w);
+      DO(printf ("%d BODIES, %d JOINTS\n",nb,nj));
+    }
+    if (nj < NUM && nb > 2 && dRandReal() > 0.5) {
+      dBodyID b1 = body [dRand() % nb];
+      dBodyID b2 = body [dRand() % nb];
+      if (b1 != b2) {
+        DO(printf ("creating joint, attaching to %p,%p\n",b1,b2));
+        joint[nj] = dJointCreateBall (w,0);
+        DO(printf ("\t-->%p\n",joint[nj]));
+        checkWorld (w);
+        dJointAttach (joint[nj],b1,b2);
+        nj++;
+        checkWorld (w);
+        DO(printf ("%d BODIES, %d JOINTS\n",nb,nj));
+      }
+    }
+    if (nj > 0 && nb > 2 && dRandReal() > 0.5) {
+      dBodyID b1 = body [dRand() % nb];
+      dBodyID b2 = body [dRand() % nb];
+      if (b1 != b2) {
+        int k = dRand() % nj;
+        DO(printf ("reattaching joint %p\n",joint[k]));
+        dJointAttach (joint[k],b1,b2);
+        checkWorld (w);
+        DO(printf ("%d BODIES, %d JOINTS\n",nb,nj));
+      }
+    }
+    if (nb > 0 && dRandReal() > 0.5) {
+      int k = dRand() % nb;
+      DO(printf ("destroying body %p\n",body[k]));
+      dBodyDestroy (body[k]);
+      checkWorld (w);
+      for (; k < (NUM-1); k++) body[k] = body[k+1];
+      nb--;
+      DO(printf ("%d BODIES, %d JOINTS\n",nb,nj));
+    }
+    if (nj > 0 && dRandReal() > 0.5) {
+      int k = dRand() % nj;
+      DO(printf ("destroying joint %p\n",joint[k]));
+      dJointDestroy (joint[k]);
+      checkWorld (w);
+      for (; k < (NUM-1); k++) joint[k] = joint[k+1];
+      nj--;
+      DO(printf ("%d BODIES, %d JOINTS\n",nb,nj));
+    }
+  }
+
+  /*
+  printf ("creating world\n");
+  dWorldID w = dWorldCreate();
+  checkWorld (w);
+  printf ("creating body\n");
+  dBodyID b1 = dBodyCreate (w);
+  checkWorld (w);
+  printf ("creating body\n");
+  dBodyID b2 = dBodyCreate (w);
+  checkWorld (w);
+  printf ("creating joint\n");
+  dJointID j = dJointCreateBall (w);
+  checkWorld (w);
+  printf ("attaching joint\n");
+  dJointAttach (j,b1,b2);
+  checkWorld (w);
+  printf ("destroying joint\n");
+  dJointDestroy (j);
+  checkWorld (w);
+  printf ("destroying body\n");
+  dBodyDestroy (b1);
+  checkWorld (w);
+  printf ("destroying body\n");
+  dBodyDestroy (b2);
+  checkWorld (w);
+  printf ("destroying world\n");
+  dWorldDestroy (w);
+  */
+}