bullet3/Demos/ConstraintDemo/ConstraintDemo.cpp

/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/

This software is provided 'as-is', without any express or implied warranty.
In no event will the authors be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software for any purpose, 
including commercial applications, and to alter it and redistribute it freely, 
subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/




#include "btBulletDynamicsCommon.h"
#include "LinearMath/btIDebugDraw.h"

#include "GLDebugDrawer.h"

#include "BMF_Api.h"
#include <stdio.h> //printf debugging

#include "ConstraintDemo.h"
#include "GL_ShapeDrawer.h"
#include "GlutStuff.h"

const int numObjects = 3;

#define CUBE_HALF_EXTENTS 1.f



btTransform sliderTransform;
btVector3 lowerSliderLimit = btVector3(-10,0,0);
btVector3 hiSliderLimit = btVector3(10,0,0);

btRigidBody* d6body0 =0;

void	drawLimit()
{
		btVector3 from = sliderTransform*lowerSliderLimit;
		btVector3 to = sliderTransform*hiSliderLimit;
		btVector3 color(255,0,0);
		glBegin(GL_LINES);
		glColor3f(color.getX(), color.getY(), color.getZ());
		glVertex3d(from.getX(), from.getY(), from.getZ());
		glVertex3d(to.getX(), to.getY(), to.getZ());
		if (d6body0)
		{
			from = d6body0->getWorldTransform().getOrigin();
			to = from + d6body0->getWorldTransform().getBasis() * btVector3(0,0,10);
			glVertex3d(from.getX(), from.getY(), from.getZ());
			glVertex3d(to.getX(), to.getY(), to.getZ());
		}
		glEnd();
}



void	ConstraintDemo::initPhysics()
{
	setCameraDistance(26.f);

	m_collisionConfiguration = new btDefaultCollisionConfiguration();
	m_dispatcher = new btCollisionDispatcher(m_collisionConfiguration);
	btVector3 worldMin(-1000,-1000,-1000);
	btVector3 worldMax(1000,1000,1000);
	m_overlappingPairCache = new btAxisSweep3(worldMin,worldMax);
	m_constraintSolver = new btSequentialImpulseConstraintSolver();
	m_dynamicsWorld = new btDiscreteDynamicsWorld(m_dispatcher,m_overlappingPairCache,m_constraintSolver,m_collisionConfiguration);

	btCollisionShape* shape = new btBoxShape(btVector3(CUBE_HALF_EXTENTS,CUBE_HALF_EXTENTS,CUBE_HALF_EXTENTS));
	m_collisionShapes.push_back(shape);
	btTransform trans;
	trans.setIdentity();
	trans.setOrigin(btVector3(0,20,0));

	float mass = 1.f;
	//point to point constraint (ball socket)
	{
		btRigidBody* body0 = localCreateRigidBody( mass,trans,shape);
		trans.setOrigin(btVector3(2*CUBE_HALF_EXTENTS,20,0));

		mass = 1.f;
		btRigidBody* body1 = 0;//localCreateRigidBody( mass,trans,shape);
		//body1->setActivationState(DISABLE_DEACTIVATION);
		//body1->setDamping(0.3,0.3);

		btVector3 pivotInA(CUBE_HALF_EXTENTS,-CUBE_HALF_EXTENTS,-CUBE_HALF_EXTENTS);
		btVector3 axisInA(0,0,1);

		btVector3 pivotInB = body1 ? body1->getCenterOfMassTransform().inverse()(body0->getCenterOfMassTransform()(pivotInA)) : pivotInA;
		btVector3 axisInB = body1? 
			(body1->getCenterOfMassTransform().getBasis().inverse()*(body1->getCenterOfMassTransform().getBasis() * axisInA)) : 
		body0->getCenterOfMassTransform().getBasis() * axisInA;

		//btTypedConstraint* p2p = new btPoint2PointConstraint(*body0,*body1,pivotInA,pivotInB);
		//btTypedConstraint* hinge = new btHingeConstraint(*body0,*body1,pivotInA,pivotInB,axisInA,axisInB);
		btHingeConstraint* hinge = new btHingeConstraint(*body0,pivotInA,axisInA);
		
		//use zero targetVelocity and a small maxMotorImpulse to simulate joint friction
		//float	targetVelocity = 0.f;
		//float	maxMotorImpulse = 0.01;
		float	targetVelocity = 1.f;
		float	maxMotorImpulse = 1.0f;
		hinge->enableAngularMotor(true,targetVelocity,maxMotorImpulse);

		m_dynamicsWorld->addConstraint(hinge);//p2p);

	}

	
	//create a slider, using the generic D6 constraint
	{
		mass = 1.f;
		btVector3 sliderWorldPos(0,10,0);
		btVector3 sliderAxis(1,0,0);
		btScalar angle=0.f;//SIMD_RADS_PER_DEG * 10.f;
		btMatrix3x3 sliderOrientation(btQuaternion(sliderAxis ,angle));
		trans.setIdentity();
		trans.setOrigin(sliderWorldPos);
		//trans.setBasis(sliderOrientation);
		sliderTransform = trans;

		d6body0 = localCreateRigidBody( mass,trans,shape);
		d6body0->setActivationState(DISABLE_DEACTIVATION);
		btRigidBody* fixedBody1 = localCreateRigidBody(0,trans,0);
		m_dynamicsWorld->addRigidBody(fixedBody1);

		btTransform frameInA, frameInB;
		frameInA = btTransform::getIdentity();
		frameInB = btTransform::getIdentity();

		bool useLinearReferenceFrameA = false;//use fixed frame B for linear limits
		btGeneric6DofConstraint* slider = new btGeneric6DofConstraint(*d6body0,*fixedBody1,frameInA,frameInB,useLinearReferenceFrameA);
		slider->setLinearLowerLimit(lowerSliderLimit);
		slider->setLinearUpperLimit(hiSliderLimit);

		//range should be small, otherwise singularities will 'explode' the constraint
		slider->setAngularLowerLimit(btVector3(10,0,0));
		slider->setAngularUpperLimit(btVector3(0,0,0));

		m_dynamicsWorld->addConstraint(slider);

	}

}

ConstraintDemo::~ConstraintDemo()
{
	//cleanup in the reverse order of creation/initialization

	int i;

	//removed/delete constraints
	for (i=m_dynamicsWorld->getNumConstraints()-1; i>=0 ;i--)
	{
		btTypedConstraint* constraint = m_dynamicsWorld->getConstraint(i);
		m_dynamicsWorld->removeConstraint(constraint);
		delete constraint;
	}

	//remove the rigidbodies from the dynamics world and delete them
	for (i=m_dynamicsWorld->getNumCollisionObjects()-1; i>=0 ;i--)
	{
		btCollisionObject* obj = m_dynamicsWorld->getCollisionObjectArray()[i];
		btRigidBody* body = btRigidBody::upcast(obj);
		if (body && body->getMotionState())
		{
			delete body->getMotionState();
		}
		m_dynamicsWorld->removeCollisionObject( obj );
		delete obj;
	}




	//delete collision shapes
	for (int j=0;j<m_collisionShapes.size();j++)
	{
		btCollisionShape* shape = m_collisionShapes[j];
		delete shape;
	}

	//delete dynamics world
	delete m_dynamicsWorld;

	//delete solver
	delete m_constraintSolver;

	//delete broadphase
	delete m_overlappingPairCache;

	//delete dispatcher
	delete m_dispatcher;

	delete m_collisionConfiguration;


}

void ConstraintDemo::clientMoveAndDisplay()
{
	
 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 

 	float dt = float(m_clock.getTimeMicroseconds()) * 0.000001f;
	m_clock.reset();
	//printf("dt = %f: ",dt);
	
	{
	 	//during idle mode, just run 1 simulation step maximum
		int maxSimSubSteps = m_idle ? 1 : 1;
		if (m_idle)
			dt = 1.0/420.f;

		int numSimSteps = m_dynamicsWorld->stepSimulation(dt,maxSimSubSteps);

		//optional but useful: debug drawing
		m_dynamicsWorld->debugDrawWorld();
	
		bool verbose = false;
		if (verbose)
		{
			if (!numSimSteps)
				printf("Interpolated transforms\n");
			else
			{
				if (numSimSteps > maxSimSubSteps)
				{
					//detect dropping frames
					printf("Dropped (%i) simulation steps out of %i\n",numSimSteps - maxSimSubSteps,numSimSteps);
				} else
				{
					printf("Simulated (%i) steps\n",numSimSteps);
				}
			}
		}
	}
	renderme();

	drawLimit();

    glFlush();
    glutSwapBuffers();
}




void ConstraintDemo::displayCallback(void) {

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 

	if (m_dynamicsWorld)
		m_dynamicsWorld->debugDrawWorld();

	drawLimit();

	renderme();

    glFlush();
    glutSwapBuffers();
}