1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
|
/*************************************************************************
* *
* 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. *
* *
*************************************************************************/
/*
Angular friction demo:
A bunch of ramps of different pitch.
A bunch of spheres with rolling friction.
*/
#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
// dynamics and collision objects
static dWorldID world = 0;
static const dReal dt = 1/REAL(60.0); // 60 fps
// Water density if units are meters and kg
static const dReal density = 1000;
// A long skinny thing
static dVector3 sides = {2,.5,.25};
// Initial angular velocity
static dVector3 omega = {5,1,2};
static dVector3 torque = {0,10,0};
static dBodyID noGyroBody;
static dBodyID expGyroBody;
static dBodyID impGyroBody;
// start simulation - set viewpoint
static void start()
{
dAllocateODEDataForThread(dAllocateMaskAll);
static float xyz[3] = {0,-4.0f,3.0f};
static float hpr[3] = {90.0000,-15.0000,0.0000};
dsSetViewpoint (xyz,hpr);
printf ("Press:\n"
"\t'a' to apply a torque\n"
"\t'r' to reset simulation.\n");
}
/**
Delete the bodies, etc.
*/
static void clear()
{
if (world) dWorldDestroy (world);
world = 0;
}
/**
Cleanup if necessary and rebuild the
world.
*/
static void reset()
{
clear();
// create world
world = dWorldCreate();
// Calculate mass for a box;
dMass boxMass;
dMassSetBox(&boxMass,density,sides[0],sides[1],sides[2]);
noGyroBody = dBodyCreate(world);// Conservation of ang-velocity
expGyroBody = dBodyCreate(world);// Explicit conservation of ang-momentum
impGyroBody = dBodyCreate(world);// Implicit conservation of ang-momentum
dBodySetMass( noGyroBody , &boxMass );
dBodySetMass( expGyroBody, &boxMass );
dBodySetMass( impGyroBody, &boxMass );
// Try to avoid collisions.
dReal sep = dCalcVectorLength3(sides);
dBodySetPosition( noGyroBody , -sep, 0, sep);
dBodySetPosition( expGyroBody, 0, 0, sep);
dBodySetPosition( impGyroBody, sep, 0, sep);
// Set the initial angular velocity
dBodySetAngularVel( noGyroBody , omega[0], omega[1], omega[2]);
dBodySetAngularVel( expGyroBody, omega[0], omega[1], omega[2]);
dBodySetAngularVel( impGyroBody, omega[0], omega[1], omega[2]);
dBodySetGyroscopicMode( noGyroBody, 0);
// We compute this ourselves using the math
// that was in the old stepper.
dBodySetGyroscopicMode(expGyroBody, 0);
// Keep things from crashing by limiting
// the angular speed of the explicit body.
// Note that this isn't necessary for
// the other two bodies.
dBodySetMaxAngularSpeed( expGyroBody, 40 );
}
static void command (int cmd)
{
switch (cmd) {
case 'a': case 'A':
dBodyAddTorque( noGyroBody, torque[0], torque[1], torque[2]);
dBodyAddTorque(expGyroBody, torque[0], torque[1], torque[2]);
dBodyAddTorque(impGyroBody, torque[0], torque[1], torque[2]);
break;
case 'r': case 'R':
reset();
break;
}
}
/**
This is the explicit computation of
gyroscopic forces.
*/
static void expStep(dBodyID body)
{
// Explicit computation
dMatrix3 I,tmp;
dMass m;
dBodyGetMass(body,&m);
const dReal* R = dBodyGetRotation(body);
// compute inertia tensor in global frame
dMultiply2_333 (tmp,m.I,R);
dMultiply0_333 (I,R,tmp);
// compute explicit rotational force
// we treat 'tmp'like a vector, but that's okay.
const dReal* w = dBodyGetAngularVel(body);
dMultiply0_331 (tmp,I,w);
dVector3 tau;
dCalcVectorCross3(tau,tmp,w);
dBodyAddTorque(body,tau[0],tau[1],tau[2]);
}
// simulation loop
static void simLoop (int pause)
{
if (!pause) {
expStep(expGyroBody);
dWorldStep (world,dt);
}
dsSetTexture (DS_WOOD);
dsSetColor(1,0,0);
dsDrawBox(dBodyGetPosition(noGyroBody ),dBodyGetRotation(noGyroBody ),sides);
dsSetColor(1,1,0);
dsDrawBox(dBodyGetPosition(expGyroBody),dBodyGetRotation(expGyroBody),sides);
dsSetColor(0,1,0);
dsDrawBox(dBodyGetPosition(impGyroBody),dBodyGetRotation(impGyroBody),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 = &command;
fn.stop = 0;
fn.path_to_textures = DRAWSTUFF_TEXTURE_PATH;
dInitODE2(0);
reset();
// run simulation
dsSimulationLoop (argc,argv,352,288,&fn);
clear();
dCloseODE();
return 0;
}
|
