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authorsanine <sanine.not@pm.me>2022-10-01 20:59:36 -0500
committersanine <sanine.not@pm.me>2022-10-01 20:59:36 -0500
commitc5fc66ee58f2c60f2d226868bb1cf5b91badaf53 (patch)
tree277dd280daf10bf77013236b8edfa5f88708c7e0 /libs/ode-0.16.1/ode/demo/demo_friction.cpp
parent1cf9cc3408af7008451f9133fb95af66a9697d15 (diff)
add ode
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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. *
+ * *
+ *************************************************************************/
+
+/*
+
+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;
+}