Bullet physics OpenGL Rigid Body Application Template rigid simulation in bullet

Use the bullet physical engine to implement a rigid-body free drop simulation Template

Bullet

Main. cpp

#include <GLUT/glut.h>#include <cstdlib> /* for exit */#include <vector>#include "btBulletDynamicsCommon.h"#include "BulletCollision/Gimpact/btGImpactShape.h"#include "BulletCollision/Gimpact/btGImpactCollisionAlgorithm.h"using namespace std;float zoom = 2000.f;float rotx = 20;float roty = 0;float tx = 0;float ty = 0;int lastx=0;int lasty=0;unsigned char Buttons[3] = {0};float lightPosition[] = { -200, 300, 300, 1.0f};float ambientLight[] = { 0.2f, 0.2f, 0.2f, 1.0f };float diffuseLight[] = { 0.8f, 0.8f, 0.8, 1.0f };float specularLight[] = { 0.5f, 0.5f, 0.5f, 1.0f };btDiscreteDynamicsWorld* mp_btDynamicsWorld = NULL;btRigidBody *cube = NULL;btRigidBody *ground = NULL;void InitWorld(){    btDefaultCollisionConfiguration *config = new btDefaultCollisionConfiguration();    btCollisionDispatcher *dispatcher = new btCollisionDispatcher(config);        btDbvtBroadphase *broadphase = new btDbvtBroadphase();  // Dynamic AABB tree method    btSequentialImpulseConstraintSolver* solver = new btSequentialImpulseConstraintSolver();    mp_btDynamicsWorld = new btDiscreteDynamicsWorld(dispatcher, broadphase, solver, config);    mp_btDynamicsWorld->setGravity(btVector3(0, -9800, 0)); //millimeter 9.8 * 1000}void InitObject(){    //init cube    btCollisionShape *collisionShape = new btBoxShape(btVector3(300,300,300));    //initial position    btVector3 pos = btVector3(0, 600, 0);    btQuaternion qrot(0, 0, 0, 1);        btDefaultMotionState* motion_state = new btDefaultMotionState(btTransform(qrot, pos));        btScalar mass = btScalar(10);    btVector3 inertia = btVector3(0, 0, 0);//guan xing    collisionShape->calculateLocalInertia(mass, inertia);        cube = new btRigidBody(mass, motion_state, collisionShape, inertia);        btScalar restitution = btScalar(0);    cube->setRestitution(restitution);    //default 0.5    btScalar friction = btScalar(0.8);    cube->setFriction(friction);        mp_btDynamicsWorld->addRigidBody(cube);        //init ground    btCollisionShape *groundShape = new btBoxShape(btVector3(2000,5,2000)); //half size        btVector3 groundpos = btVector3(0,-150,0);    btQuaternion groundrot(0, 0, 0, 1);    btDefaultMotionState* groundMotion = new btDefaultMotionState(btTransform(groundrot, groundpos));    ground  = new btRigidBody(0.0, groundMotion, groundShape);//mass = 0 means it is a static object    btScalar rest = btScalar(1);    ground->setRestitution(rest);    mp_btDynamicsWorld->addRigidBody(ground);}void DeleteBullet(){    //cube    delete cube->getMotionState();    mp_btDynamicsWorld->removeRigidBody(cube);    delete cube;    cube = NULL;        //ground    delete ground->getMotionState();    mp_btDynamicsWorld->removeRigidBody(ground);    delete ground;    ground = NULL;        //world    delete mp_btDynamicsWorld->getBroadphase();    delete mp_btDynamicsWorld;    mp_btDynamicsWorld = NULL;}void DrawGrid(int _halfLen, int _gridNum){    glColor3f(1.0f,1.0f,1.0f);        // draw grid    glLineWidth(2);    glBegin(GL_LINES);    for(int i = -_halfLen;i <= _halfLen; i += (_halfLen/_gridNum)) {        glVertex3f(i,0,-_halfLen);        glVertex3f(i,0,_halfLen);                glVertex3f(_halfLen,0,i);        glVertex3f(-_halfLen,0,i);    }    glEnd();}void DrawCoordinate(float _flengthX, float _flengthY, float _flengthZ){    glLineWidth(5);    glBegin(GL_LINES);    glColor3f(1,0,0);    glVertex3f(0,0,0);    glVertex3f(_flengthX,0,0);    glEnd();        glBegin(GL_LINES);    glColor3f(0,1,0);    glVertex3f(0,0,0);    glVertex3f(0,_flengthY,0);    glEnd();        glBegin(GL_LINES);    glColor3f(0,0,1);    glVertex3f(0,0,0);    glVertex3f(0,0,_flengthZ);    glEnd();}void DrawBulletObject(){    //cube    btTransform trans = cube->getWorldTransform();    btScalar m[16];trans.getOpenGLMatrix(m);    glColor3f(0, 0, 1);glPushMatrix();glMultMatrixf((GLfloat*)m);    glutSolidCube(300);glPopMatrix();        //ground    glColor3f(0, 1, 0);    glPushMatrix();    glTranslatef(0, -5, 0);    glScalef(1, 0.005, 1);    glutSolidCube(2000); //half size    glPopMatrix();    }void Simulate(){    double dt = 1.f/60.0f;    if(mp_btDynamicsWorld)        mp_btDynamicsWorld->stepSimulation(dt,1);}//-------------------------------------------------------------------------------///void Display(){    Simulate();        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);            glLoadIdentity();        glTranslatef(0,0,-zoom);    glTranslatef(tx,ty,0);    glRotatef(rotx,1,0,0);    glRotatef(roty,0,1,0);            glLightfv(GL_LIGHT1, GL_AMBIENT, ambientLight);    glLightfv(GL_LIGHT1, GL_DIFFUSE, diffuseLight);    glLightfv(GL_LIGHT1, GL_SPECULAR, specularLight);    glLightfv(GL_LIGHT1, GL_POSITION, lightPosition);        glEnable(GL_LIGHT1);    glEnable(GL_LIGHTING);        glColorMaterial(GL_FRONT_AND_BACK,GL_AMBIENT_AND_DIFFUSE);    glEnable(GL_COLOR_MATERIAL);        DrawBulletObject();    glDisable( GL_LIGHTING );    glDisable(GL_COLOR_MATERIAL);        DrawGrid(1000, 10);    //DrawCoordinate(1000,1000,1000);        glutPostRedisplay();    glutSwapBuffers();}void Init(){    glShadeModel(GL_SMOOTH);    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);    glClearDepth(1.0f);    glColor4f(1.0f, 1.0f, 1.0f, 1.0f);    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);    glDepthFunc(GL_LEQUAL);    glEnable(GL_DEPTH_TEST);        glEnable(GL_CULL_FACE);        glEnable(GL_NORMALIZE);            InitWorld();    InitObject();}void Reshape(int w, int h){    // prevent divide by 0 error when minimised    if(w==0)        h = 1;        glViewport(0,0,w,h);    glMatrixMode(GL_PROJECTION);    glLoadIdentity();    gluPerspective(45,(float)w/h,0.1,5000);    glMatrixMode(GL_MODELVIEW);    glLoadIdentity();}//-------------------------------------------------------------------------------//void Motion(int x,int y){    int diffx=x-lastx;    int diffy=y-lasty;    lastx=x;    lasty=y;        if( Buttons[2] )    {        zoom -= (float)  1* diffx*2;    }    else        if( Buttons[0] )        {            rotx += (float) 1 * diffy;            roty += (float) 1 * diffx;        }        else            if( Buttons[1] )            {                tx += (float) 1 * diffx;                ty -= (float) 1 * diffy;            }    glutPostRedisplay();}//-------------------------------------------------------------------------------//void Mouse(int b,int s,int x,int y){    lastx=x;    lasty=y;    switch(b)    {        case GLUT_LEFT_BUTTON:            Buttons[0] = ((GLUT_DOWN==s)?1:0);            break;        case GLUT_MIDDLE_BUTTON:            Buttons[1] = ((GLUT_DOWN==s)?1:0);            break;        case GLUT_RIGHT_BUTTON:            Buttons[2] = ((GLUT_DOWN==s)?1:0);            break;        default:            break;    }    glutPostRedisplay();}void Keyboard(unsigned char key, int x, int y){    switch(key) {        case 'q':        case 'Q':        case 27: // ESC key            exit(0);        break;        case 'r':            DeleteBullet();            InitWorld();            InitObject();        break;        default:        break;    }}int main(int argc,char** argv){    glutInit(&argc,argv);    glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA|GLUT_DEPTH);    glutInitWindowSize(640,480);    glutInitWindowPosition(100,100);    glutCreateWindow("Bullet Framework");    glutDisplayFunc(Display);    glutReshapeFunc(Reshape);    glutMouseFunc(Mouse);    glutMotionFunc(Motion);    glutKeyboardFunc(Keyboard);    Init();        glutMainLoop();        return 0;}

Bullet physics OpenGL Rigid Body Application Template rigid simulation in bullet