利用Bullet物理引擎实现刚体的自由落体模拟的模板

Bullet下载地址

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(200,200,200));

    //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(1000,0.5,1000)); //half size

    btVector3 groundpos = btVector3(0,0,0);

    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(400);

    glPopMatrix();

    //ground

    glColor3f(0, 1, 0);

    glPushMatrix();

    glScalef(1, 0.0005, 1);

    glutSolidCube(2000); //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;

}