From c5fc66ee58f2c60f2d226868bb1cf5b91badaf53 Mon Sep 17 00:00:00 2001
From: sanine <sanine.not@pm.me>
Date: Sat, 1 Oct 2022 20:59:36 -0500
Subject: add ode

---
 libs/ode-0.16.1/ode/demo/demo_I.cpp | 253 ++++++++++++++++++++++++++++++++++++
 1 file changed, 253 insertions(+)
 create mode 100644 libs/ode-0.16.1/ode/demo/demo_I.cpp

(limited to 'libs/ode-0.16.1/ode/demo/demo_I.cpp')

diff --git a/libs/ode-0.16.1/ode/demo/demo_I.cpp b/libs/ode-0.16.1/ode/demo/demo_I.cpp
new file mode 100644
index 0000000..156a4ad
--- /dev/null
+++ b/libs/ode-0.16.1/ode/demo/demo_I.cpp
@@ -0,0 +1,253 @@
+/*************************************************************************
+ *                                                                       *
+ * 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.                     *
+ *                                                                       *
+ *************************************************************************/
+
+/*
+
+test that the rotational physics is correct.
+
+an "anchor body" has a number of other randomly positioned bodies
+("particles") attached to it by ball-and-socket joints, giving it some
+random effective inertia tensor. the effective inertia matrix is calculated,
+and then this inertia is assigned to another "test" body. a random torque is
+applied to both bodies and the difference in angular velocity and orientation
+is observed after a number of iterations.
+
+typical errors for each test cycle are about 1e-5 ... 1e-4.
+
+*/
+
+
+#include <time.h>
+#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
+#define dsDrawSphere dsDrawSphereD
+#define dsDrawCylinder dsDrawCylinderD
+#define dsDrawCapsule dsDrawCapsuleD
+#endif
+
+
+// some constants
+
+#define NUM 10			// number of particles
+#define SIDE 0.1		// visual size of the particles
+
+
+// dynamics objects an globals
+
+static dWorldID world=0;
+static dBodyID anchor_body,particle[NUM],test_body;
+static dJointID particle_joint[NUM];
+static dReal torque[3];
+static int iteration;
+
+
+// start simulation - set viewpoint
+
+static void start()
+{
+  dAllocateODEDataForThread(dAllocateMaskAll);
+
+  static float xyz[3] = {1.5572f,-1.8886f,1.5700f};
+  static float hpr[3] = {118.5000f,-17.0000f,0.0000f};
+  dsSetViewpoint (xyz,hpr);
+}
+
+
+// compute the mass parameters of a particle set. q = particle positions,
+// pm = particle masses
+
+#define _I(i,j) I[(i)*4+(j)]
+
+void computeMassParams (dMass *m, dReal q[NUM][3], dReal pm[NUM])
+{
+  int i,j;
+  dMassSetZero (m);
+  for (i=0; i<NUM; i++) {
+    m->mass += pm[i];
+    for (j=0; j<3; j++) m->c[j] += pm[i]*q[i][j];
+    m->_I(0,0) += pm[i]*(q[i][1]*q[i][1] + q[i][2]*q[i][2]);
+    m->_I(1,1) += pm[i]*(q[i][0]*q[i][0] + q[i][2]*q[i][2]);
+    m->_I(2,2) += pm[i]*(q[i][0]*q[i][0] + q[i][1]*q[i][1]);
+    m->_I(0,1) -= pm[i]*(q[i][0]*q[i][1]);
+    m->_I(0,2) -= pm[i]*(q[i][0]*q[i][2]);
+    m->_I(1,2) -= pm[i]*(q[i][1]*q[i][2]);
+  }
+  for (j=0; j<3; j++) m->c[j] /= m->mass;
+  m->_I(1,0) = m->_I(0,1);
+  m->_I(2,0) = m->_I(0,2);
+  m->_I(2,1) = m->_I(1,2);
+}
+
+
+void reset_test()
+{
+  int i;
+  dMass m,anchor_m;
+  dReal q[NUM][3], pm[NUM];	// particle positions and masses
+  dReal pos1[3] = {1,0,1};	// point of reference (POR)
+  dReal pos2[3] = {-1,0,1};	// point of reference (POR)
+
+  // make random particle positions (relative to POR) and masses
+  for (i=0; i<NUM; i++) {
+    pm[i] = dRandReal()+0.1;
+    q[i][0] = dRandReal()-0.5;
+    q[i][1] = dRandReal()-0.5;
+    q[i][2] = dRandReal()-0.5;
+  }
+
+  // adjust particle positions so centor of mass = POR
+  computeMassParams (&m,q,pm);
+  for (i=0; i<NUM; i++) {
+    q[i][0] -= m.c[0];
+    q[i][1] -= m.c[1];
+    q[i][2] -= m.c[2];
+  }
+
+  if (world) dWorldDestroy (world);
+  world = dWorldCreate();
+
+  anchor_body = dBodyCreate (world);
+  dBodySetPosition (anchor_body,pos1[0],pos1[1],pos1[2]);
+  dMassSetBox (&anchor_m,1,SIDE,SIDE,SIDE);
+  dMassAdjust (&anchor_m,0.1);
+  dBodySetMass (anchor_body,&anchor_m);
+
+  for (i=0; i<NUM; i++) {
+    particle[i] = dBodyCreate (world);
+    dBodySetPosition (particle[i],
+		      pos1[0]+q[i][0],pos1[1]+q[i][1],pos1[2]+q[i][2]);
+    dMassSetBox (&m,1,SIDE,SIDE,SIDE);
+    dMassAdjust (&m,pm[i]);
+    dBodySetMass (particle[i],&m);
+  }
+
+  for (i=0; i < NUM; i++) {
+    particle_joint[i] = dJointCreateBall (world,0);
+    dJointAttach (particle_joint[i],anchor_body,particle[i]);
+    const dReal *p = dBodyGetPosition (particle[i]);
+    dJointSetBallAnchor (particle_joint[i],p[0],p[1],p[2]);
+  }
+
+  // make test_body with the same mass and inertia of the anchor_body plus
+  // all the particles
+
+  test_body = dBodyCreate (world);
+  dBodySetPosition (test_body,pos2[0],pos2[1],pos2[2]);
+  computeMassParams (&m,q,pm);
+  m.mass += anchor_m.mass;
+  for (i=0; i<12; i++) m.I[i] = m.I[i] + anchor_m.I[i];
+  dBodySetMass (test_body,&m);
+
+  // rotate the test and anchor bodies by a random amount
+  dQuaternion qrot;
+  for (i=0; i<4; i++) qrot[i] = dRandReal()-0.5;
+  dNormalize4 (qrot);
+  dBodySetQuaternion (anchor_body,qrot);
+  dBodySetQuaternion (test_body,qrot);
+  dMatrix3 R;
+  dQtoR (qrot,R);
+  for (i=0; i<NUM; i++) {
+    dVector3 v;
+    dMultiply0 (v,R,&q[i][0],3,3,1);
+    dBodySetPosition (particle[i],pos1[0]+v[0],pos1[1]+v[1],pos1[2]+v[2]);
+  }
+
+  // set random torque
+  for (i=0; i<3; i++) torque[i] = (dRandReal()-0.5) * 0.1;
+
+
+  iteration=0;
+}
+
+
+// simulation loop
+
+static void simLoop (int pause)
+{
+  if (!pause) {
+    dBodyAddTorque (anchor_body,torque[0],torque[1],torque[2]);
+    dBodyAddTorque (test_body,torque[0],torque[1],torque[2]);
+    dWorldStep (world,0.03);
+
+    iteration++;
+    if (iteration >= 100) {
+      // measure the difference between the anchor and test bodies
+      const dReal *w1 = dBodyGetAngularVel (anchor_body);
+      const dReal *w2 = dBodyGetAngularVel (test_body);
+      const dReal *q1 = dBodyGetQuaternion (anchor_body);
+      const dReal *q2 = dBodyGetQuaternion (test_body);
+      dReal maxdiff = dMaxDifference (w1,w2,1,3);
+      printf ("w-error = %.4e  (%.2f,%.2f,%.2f) and (%.2f,%.2f,%.2f)\n",
+	      maxdiff,w1[0],w1[1],w1[2],w2[0],w2[1],w2[2]);
+      maxdiff = dMaxDifference (q1,q2,1,4);
+      printf ("q-error = %.4e\n",maxdiff);
+      reset_test();
+    }
+  }
+
+  dReal sides[3] = {SIDE,SIDE,SIDE};
+  dReal sides2[3] = {6*SIDE,6*SIDE,6*SIDE};
+  dReal sides3[3] = {3*SIDE,3*SIDE,3*SIDE};
+  dsSetColor (1,1,1);
+  dsDrawBox (dBodyGetPosition(anchor_body), dBodyGetRotation(anchor_body),
+	     sides3);
+  dsSetColor (1,0,0);
+  dsDrawBox (dBodyGetPosition(test_body), dBodyGetRotation(test_body), sides2);
+  dsSetColor (1,1,0);
+  for (int i=0; i<NUM; i++)
+    dsDrawBox (dBodyGetPosition (particle[i]),
+	       dBodyGetRotation (particle[i]), sides);
+}
+
+
+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 = 0;
+  fn.stop = 0;
+  fn.path_to_textures = DRAWSTUFF_TEXTURE_PATH;
+
+  dInitODE2(0);
+  dRandSetSeed (time(0));
+  reset_test();
+
+  // run simulation
+  dsSimulationLoop (argc,argv,352,288,&fn);
+
+  dWorldDestroy (world);
+  dCloseODE();
+  return 0;
+}
-- 
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