source: code/branches/ode/ode-0.9/ode/demo/demo_hinge.cpp @ 216

/*************************************************************************
 *                                                                       *
 * 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.                     *
 *                                                                       *
 *************************************************************************/

#include <ode/ode.h>
#include <drawstuff/drawstuff.h>

#ifdef _MSC_VER
#pragma warning(disable:4244 4305)  // for VC++, no precision loss complaints
#endif

// select correct drawing functions
#ifdef dDOUBLE
#define dsDrawBox dsDrawBoxD
#endif


// some constants
#define SIDE (0.5f)     // side length of a box
#define MASS (1.0)      // mass of a box


// dynamics and collision objects
static dWorldID world;
static dBodyID body[2];
static dJointID hinge;


// state set by keyboard commands
static int occasional_error = 0;


// start simulation - set viewpoint

static void start()
{
  static float xyz[3] = {1.0382f,-1.0811f,1.4700f};
  static float hpr[3] = {135.0000f,-19.5000f,0.0000f};
  dsSetViewpoint (xyz,hpr);
  printf ("Press 'e' to start/stop occasional error.\n");
}


// called when a key pressed

static void command (int cmd)
{
  if (cmd == 'e' || cmd == 'E') {
    occasional_error ^= 1;
  }
}


// simulation loop

static void simLoop (int pause)
{
  const dReal kd = -0.3;        // angular damping constant
  if (!pause) {
    // add an oscillating torque to body 0, and also damp its rotational motion
    static dReal a=0;
    const dReal *w = dBodyGetAngularVel (body[0]);
    dBodyAddTorque (body[0],kd*w[0],kd*w[1]+0.1*cos(a),kd*w[2]+0.1*sin(a));
    dWorldStep (world,0.05);
    a += 0.01;

    // occasionally re-orient one of the bodies to create a deliberate error.
    if (occasional_error) {
      static int count = 0;
      if ((count % 20)==0) {
        // randomly adjust orientation of body[0]
        const dReal *R1;
        dMatrix3 R2,R3;
        R1 = dBodyGetRotation (body[0]);
        dRFromAxisAndAngle (R2,dRandReal()-0.5,dRandReal()-0.5,
                            dRandReal()-0.5,dRandReal()-0.5);
        dMultiply0 (R3,R1,R2,3,3,3);
        dBodySetRotation (body[0],R3);

        // randomly adjust position of body[0]
        const dReal *pos = dBodyGetPosition (body[0]);
        dBodySetPosition (body[0],
                          pos[0]+0.2*(dRandReal()-0.5),
                          pos[1]+0.2*(dRandReal()-0.5),
                          pos[2]+0.2*(dRandReal()-0.5));
      }
      count++;
    }
  }

  dReal sides1[3] = {SIDE,SIDE,SIDE};
  dReal sides2[3] = {SIDE,SIDE,SIDE*0.8f};
  dsSetTexture (DS_WOOD);
  dsSetColor (1,1,0);
  dsDrawBox (dBodyGetPosition(body[0]),dBodyGetRotation(body[0]),sides1);
  dsSetColor (0,1,1);
  dsDrawBox (dBodyGetPosition(body[1]),dBodyGetRotation(body[1]),sides2);
}


int main (int argc, char **argv)
{
  // setup pointers to drawstuff callback functions
  dsFunctions fn;
  fn.version = DS_VERSION;
  fn.start = &start;
  fn.step = &simLoop;
  fn.command = &command;
  fn.stop = 0;
  fn.path_to_textures = "../../drawstuff/textures";
  if(argc==2)
    {
        fn.path_to_textures = argv[1];
    }

  // create world
  dInitODE();
  world = dWorldCreate();

  dMass m;
  dMassSetBox (&m,1,SIDE,SIDE,SIDE);
  dMassAdjust (&m,MASS);

  dQuaternion q;
  dQFromAxisAndAngle (q,1,1,0,0.25*M_PI);

  body[0] = dBodyCreate (world);
  dBodySetMass (body[0],&m);
  dBodySetPosition (body[0],0.5*SIDE,0.5*SIDE,1);
  dBodySetQuaternion (body[0],q);

  body[1] = dBodyCreate (world);
  dBodySetMass (body[1],&m);
  dBodySetPosition (body[1],-0.5*SIDE,-0.5*SIDE,1);
  dBodySetQuaternion (body[1],q);

  hinge = dJointCreateHinge (world,0);
  dJointAttach (hinge,body[0],body[1]);
  dJointSetHingeAnchor (hinge,0,0,1);
  dJointSetHingeAxis (hinge,1,-1,1.41421356);

  // run simulation
  dsSimulationLoop (argc,argv,352,288,&fn);

  dWorldDestroy (world);
  dCloseODE();
  return 0;
}