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/* -------------------------------------------------------------------------- *
* Simbody(tm) Example: Long Pendulum *
* -------------------------------------------------------------------------- *
* This is part of the SimTK biosimulation toolkit originating from *
* Simbios, the NIH National Center for Physics-Based Simulation of *
* Biological Structures at Stanford, funded under the NIH Roadmap for *
* Medical Research, grant U54 GM072970. See https://simtk.org/home/simbody. *
* *
* Portions copyright (c) 2008-13 Stanford University and the Authors. *
* Authors: Michael Sherman *
* Contributors: *
* *
* Licensed under the Apache License, Version 2.0 (the "License"); you may *
* not use this file except in compliance with the License. You may obtain a *
* copy of the License at http://www.apache.org/licenses/LICENSE-2.0. *
* *
* Unless required by applicable law or agreed to in writing, software *
* distributed under the License is distributed on an "AS IS" BASIS, *
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
* See the License for the specific language governing permissions and *
* limitations under the License. *
* -------------------------------------------------------------------------- */
/* Simbody ExampleLongPendulum
This example shows how to build a linked chain of bodies programmatically,
simulate it, and produce a simple animation while it is simulating. */
#include "Simbody.h"
#include <iostream>
using namespace SimTK;
int main() {
try {
// Create the system.
MultibodySystem system; system.setUseUniformBackground(true);
SimbodyMatterSubsystem matter(system);
GeneralForceSubsystem forces(system);
Force::UniformGravity gravity(forces, matter, Vec3(0, -9.8, 0));
Body::Rigid pendulumBody(MassProperties(1.0, Vec3(0), Inertia(1)));
pendulumBody.addDecoration(Transform(), DecorativeSphere(0.1));
MobilizedBody lastBody = matter.Ground();
for (int i = 0; i < 10; ++i) {
MobilizedBody::Ball pendulum(lastBody, Transform(Vec3(0)),
pendulumBody, Transform(Vec3(0, 1, 0)));
lastBody = pendulum;
}
Visualizer viz(system);
system.addEventReporter(new Visualizer::Reporter(viz, 1./30));
// Initialize the system and state.
system.realizeTopology();
State state = system.getDefaultState();
Random::Gaussian random;
for (int i = 0; i < state.getNQ(); ++i)
state.updQ()[i] = random.getValue();
// Simulate it.
RungeKuttaMersonIntegrator integ(system);
TimeStepper ts(system, integ);
ts.initialize(state);
ts.stepTo(10.0);
} catch(const std::exception& e) {
std::cout << "EXCEPTION: " << e.what() << std::endl;
return 1;
} catch (...) {
std::cout << "UNKNOWN EXCEPTION\n";
return 1;
}
return 0;
}
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