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_friction.cpp | 205 +++++++++++++++++++++++++++++
 1 file changed, 205 insertions(+)
 create mode 100644 libs/ode-0.16.1/ode/demo/demo_friction.cpp

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

diff --git a/libs/ode-0.16.1/ode/demo/demo_friction.cpp b/libs/ode-0.16.1/ode/demo/demo_friction.cpp
new file mode 100644
index 0000000..f6260bb
--- /dev/null
+++ b/libs/ode-0.16.1/ode/demo/demo_friction.cpp
@@ -0,0 +1,205 @@
+/*************************************************************************
+ *                                                                       *
+ * 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 the Coulomb friction approximation.
+
+a 10x10 array of boxes is made, each of which rests on the ground.
+a horizantal force is applied to each box to try and get it to slide.
+box[i][j] has a mass (i+1)*MASS and a force (j+1)*FORCE. by the Coloumb
+friction model, the box should only slide if the force is greater than MU
+times the contact normal force, i.e.
+
+  f > MU * body_mass * GRAVITY
+  (j+1)*FORCE > MU * (i+1)*MASS * GRAVITY
+  (j+1) > (i+1) * (MU*MASS*GRAVITY/FORCE)
+  (j+1) > (i+1) * k
+
+this should be independent of the number of contact points, as N contact
+points will each have 1/N'th the normal force but the pushing force will
+have to overcome N contacts. the constants are chosen so that k=1.
+thus you should see a triangle made of half the bodies in the array start to
+slide.
+
+*/
+
+
+#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 LENGTH 0.2	// box length & width
+#define HEIGHT 0.05	// box height
+#define MASS 0.2	// mass of box[i][j] = (i+1) * MASS
+#define FORCE 0.05	// force applied to box[i][j] = (j+1) * FORCE
+#define MU 0.5		// the global mu to use
+#define GRAVITY 0.5	// the global gravity to use
+#define N1 10		// number of different forces to try
+#define N2 10		// number of different masses to try
+
+
+// dynamics and collision objects
+
+static dWorldID world;
+static dSpaceID space;
+static dBodyID body[N1][N2];
+static dJointGroupID contactgroup;
+static dGeomID ground;
+static dGeomID box[N1][N2];
+
+
+
+// this is called by dSpaceCollide when two objects in space are
+// potentially colliding.
+
+static void nearCallback (void *, dGeomID o1, dGeomID o2)
+{
+  int i;
+
+  // only collide things with the ground
+  int g1 = (o1 == ground);
+  int g2 = (o2 == ground);
+  if (!(g1 ^ g2)) return;
+
+  dBodyID b1 = dGeomGetBody(o1);
+  dBodyID b2 = dGeomGetBody(o2);
+
+  dContact contact[3];		// up to 3 contacts per box
+  for (i=0; i<3; i++) {
+    contact[i].surface.mode = dContactSoftCFM | dContactApprox1;
+    contact[i].surface.mu = MU;
+    contact[i].surface.soft_cfm = 0.01;
+  }
+  if (int numc = dCollide (o1,o2,3,&contact[0].geom,sizeof(dContact))) {
+    for (i=0; i<numc; i++) {
+      dJointID c = dJointCreateContact (world,contactgroup,contact+i);
+      dJointAttach (c,b1,b2);
+    }
+  }
+}
+
+
+// start simulation - set viewpoint
+
+static void start()
+{
+  dAllocateODEDataForThread(dAllocateMaskAll);
+
+  static float xyz[3] = {1.7772,-0.7924,2.7600};
+  static float hpr[3] = {90.0000,-54.0000,0.0000};
+  dsSetViewpoint (xyz,hpr);
+}
+
+
+// simulation loop
+
+static void simLoop (int pause)
+{
+  int i;
+  if (!pause) {
+    // apply forces to all bodies
+    for (i=0; i<N1; i++) {
+      for (int j=0; j<N2; j++) {
+	dBodyAddForce (body[i][j],FORCE*(i+1),0,0);
+      }
+    }
+
+    dSpaceCollide (space,0,&nearCallback);
+    dWorldStep (world,0.05);
+
+    // remove all contact joints
+    dJointGroupEmpty (contactgroup);
+  }
+
+  dsSetColor (1,0,1);
+  dReal sides[3] = {LENGTH,LENGTH,HEIGHT};
+  for (i=0; i<N1; i++) {
+    for (int j=0; j<N2; j++) {
+      dsDrawBox (dGeomGetPosition(box[i][j]),dGeomGetRotation(box[i][j]),
+		 sides);
+    }
+  }
+}
+
+
+int main (int argc, char **argv)
+{
+  int i,j;
+  dMass m;
+
+  // 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;
+
+  // create world
+  dInitODE2(0);
+  world = dWorldCreate();
+  space = dHashSpaceCreate (0);
+  contactgroup = dJointGroupCreate (0);
+  dWorldSetGravity (world,0,0,-GRAVITY);
+  ground = dCreatePlane (space,0,0,1,0);
+
+  // bodies
+  for (i=0; i<N1; i++) {
+    for (j=0; j<N2; j++) {
+      body[i][j] = dBodyCreate (world);
+      dMassSetBox (&m,1,LENGTH,LENGTH,HEIGHT);
+      dMassAdjust (&m,MASS*(j+1));
+      dBodySetMass (body[i][j],&m);
+      dBodySetPosition (body[i][j],i*2*LENGTH,j*2*LENGTH,HEIGHT*0.5);
+
+      box[i][j] = dCreateBox (space,LENGTH,LENGTH,HEIGHT);
+      dGeomSetBody (box[i][j],body[i][j]);
+    }
+  }
+
+  // run simulation
+  dsSimulationLoop (argc,argv,352,288,&fn);
+
+  dJointGroupDestroy (contactgroup);
+  dSpaceDestroy (space);
+  dWorldDestroy (world);
+  dCloseODE();
+  return 0;
+}
-- 
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