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thirdparty/ode-0.16.5/ode/demo/demo_hinge.cpp

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+/*************************************************************************
+ *                                                                       *
+ * 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>
+#include "texturepath.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()
+{
+  dAllocateODEDataForThread(dAllocateMaskAll);
+
+  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_TEXTURE_PATH;
+
+  // create world
+  dInitODE2(0);
+  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;
+}