Rolling and spinning friction example (demo_IRR_friction.cpp)

A benchmark that show the feature of spinning friction (aka 'drilling' friction) and rolling friction.

These types of frictions are useful for rolling objects like wheels, spheres etc. and can be optionally turned on.

This tutorial shows how to:

• enable rolling and spinning friction.
• impose initial velocity and angular velocity to objects.
  

// =============================================================================
// PROJECT CHRONO - http://projectchrono.org
//
// Copyright (c) 2014 projectchrono.org
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be found
// in the LICENSE file at the top level of the distribution and at
// http://projectchrono.org/license-chrono.txt.
//
// =============================================================================
// Authors: Alessandro Tasora
// =============================================================================
//
// Demo code about
// - using rolling friction (not only sliding and static friction, available in
//   all objects by default)
// - optional sharing of some assets (visualization stuff)
//
// =============================================================================
 
#include "chrono/physics/ChSystemNSC.h"
#include "chrono/physics/ChBodyEasy.h"
#include "chrono/utils/ChUtilsCreators.h"
 
#include "chrono_irrlicht/ChIrrApp.h"
 
// Use the namespaces of Chrono
using namespace chrono;
using namespace chrono::irrlicht;
 
// Use the main namespaces of Irrlicht
using namespace irr;
using namespace irr::core;
using namespace irr::scene;
using namespace irr::video;
using namespace irr::io;
using namespace irr::gui;
 
int main(int argc, char* argv[]) {
    GetLog() << "Copyright (c) 2017 projectchrono.org\nChrono version: " << CHRONO_VERSION << "\n\n";
 
    // Create a physical system
    ChSystemNSC mphysicalSystem;
 
    // Create the Irrlicht visualization, attach camera and lights, set sky and logo
    ChIrrApp application(&mphysicalSystem, L"Rolling friction", core::dimension2d<u32>(800, 600), false, true);
    ChIrrWizard::add_typical_Logo(application.GetDevice());
    ChIrrWizard::add_typical_Sky(application.GetDevice());
    ChIrrWizard::add_typical_Lights(application.GetDevice(), vector3df(30.f, 100.f, 30.f),
                                    vector3df(-30.f, 100.f, -30.f));
    ChIrrWizard::add_typical_Camera(application.GetDevice(), core::vector3df(0, 14, -20));
 
    // Create all the rigid bodies.
    double mradius = 0.5;
    double density = 1000;
 
    // Create a texture asset. It can be shared between bodies.
    auto textureasset = chrono_types::make_shared<ChTexture>(GetChronoDataFile("textures/bluewhite.png"));
 
    // Create some spheres that roll horizontally, with increasing rolling friction values
    for (int bi = 0; bi < 10; bi++) {
        auto mat = chrono_types::make_shared<ChMaterialSurfaceNSC>();
        mat->SetFriction(0.4f);
        mat->SetRollingFriction(((float)bi / 10) * 0.05f);
 
        auto msphereBody = chrono_types::make_shared<ChBodyEasySphere>(mradius,  // radius size
                                                                       1000,     // density
                                                                       true,     // visualization?
                                                                       true,     // collision?
                                                                       mat);     // contact material
 
        // Set some properties
        msphereBody->SetPos(ChVector<>(-7, mradius - 0.5, -5 + bi * mradius * 2.5));
        msphereBody->AddAsset(textureasset);  // assets can be shared
 
        // Set initial speed: rolling in horizontal direction
        double initial_angspeed = 10;
        double initial_linspeed = initial_angspeed * mradius;
        msphereBody->SetWvel_par(ChVector<>(0, 0, -initial_angspeed));
        msphereBody->SetPos_dt(ChVector<>(initial_linspeed, 0, 0));
 
        // Add to the system
        mphysicalSystem.Add(msphereBody);
    }
 
    // Create some spheres that spin on place, for a 'drilling friction' case, with increasing spinning friction values
    for (int bi = 0; bi < 10; bi++) {
        auto mat = chrono_types::make_shared<ChMaterialSurfaceNSC>();
        mat->SetFriction(0.4f);
        mat->SetSpinningFriction(((float)bi / 10) * 0.02f);
 
        auto msphereBody = chrono_types::make_shared<ChBodyEasySphere>(mradius,  // radius size
                                                                       1000,     // density
                                                                       true,     // visualization?
                                                                       true,     // collision?
                                                                       mat);     // contact material
        // Set some properties
        msphereBody->SetPos(ChVector<>(-8, 1 + mradius - 0.5, -5 + bi * mradius * 2.5));
        msphereBody->AddAsset(textureasset);  // assets can be shared
 
        // Set initial speed: spinning in vertical direction
        msphereBody->SetWvel_par(ChVector<>(0, 20, 0));
 
        // Add to the system
        mphysicalSystem.Add(msphereBody);
 
        // Notes:
        // - setting nonzero spinning friction and/or setting nonzero rolling friction
        //   affects the speed of the solver (each contact eats 2x of CPU time repsect to the
        //   case of simple sliding/staic contact)
        // - avoid using zero spinning friction with nonzero rolling friction.
    }
 
    // Create a container fixed to ground
    auto bin = chrono_types::make_shared<ChBody>();
    bin->SetPos(ChVector<>(0, -1, 0));
    bin->SetBodyFixed(true);
    bin->SetCollide(true);
 
    // Set rolling and friction coefficients for the container.
    // By default, the composite material will use the minimum value for an interacting collision pair.
    auto bin_mat = chrono_types::make_shared<ChMaterialSurfaceNSC>();
    bin_mat->SetRollingFriction(1);
    bin_mat->SetSpinningFriction(1);
 
    // Add collision geometry and visualization shapes for the floor and the 4 walls
    bin->GetCollisionModel()->ClearModel();
    utils::AddBoxGeometry(bin.get(), bin_mat, ChVector<>(20, 1, 20) / 2.0, ChVector<>(0, 0, 0));
    utils::AddBoxGeometry(bin.get(), bin_mat, ChVector<>(1, 2, 20.99) / 2.0, ChVector<>(-10, 1, 0));
    utils::AddBoxGeometry(bin.get(), bin_mat, ChVector<>(1, 2, 20.99) / 2.0, ChVector<>(10, 1, 0));
    utils::AddBoxGeometry(bin.get(), bin_mat, ChVector<>(20.99, 2, 1) / 2.0, ChVector<>(0, 1, -10));
    utils::AddBoxGeometry(bin.get(), bin_mat, ChVector<>(20.99, 2, 1) / 2.0, ChVector<>(0, 1, 10));
    bin->GetCollisionModel()->BuildModel();
 
    bin->AddAsset(chrono_types::make_shared<ChTexture>(GetChronoDataFile("textures/blue.png")));
 
    mphysicalSystem.Add(bin);
 
    // Complete asset construction
    application.AssetBindAll();
    application.AssetUpdateAll();
 
    // Modify some setting of the physical system for the simulation
    mphysicalSystem.SetSolverType(ChSolver::Type::APGD);
    mphysicalSystem.SetSolverMaxIterations(100);
 
    // Simulation loop
    application.SetTimestep(0.005);
    application.SetTryRealtime(true);
 
    while (application.GetDevice()->run()) {
        application.BeginScene(true, true, SColor(255, 140, 161, 192));
        application.DrawAll();
        application.DoStep();
        application.EndScene();
    }
 
    return 0;
}