Home of Bullet and PyBullet:
physics simulation for games, visual effects, robotics and reinforcement learning.

使用:
README.md 中已描述:

Windows

Click on build_visual_studio_vr_pybullet_double.bat and open build3/vs2010/0MySolution.sln
When asked, convert the projects to a newer version of Visual Studio.
If you installed Python in the C:\ root directory, the batch file should find it automatically.
Otherwise, edit this batch file to choose where Python include/lib directories are located.

用VS2015開啟也可以, 然後編譯執行. 沒太多可述說的

/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2003-2007 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.
*/
 


///-----includes_start-----
#include "btBulletDynamicsCommon.h"
#include <stdio.h>

/// This is a Hello World program for running a basic Bullet physics simulation

// Bullet模擬剛體動畫的一般流程為：
// 初始化場景資料->設定場景的重力等引數->建立邊界碰撞體->建立碰撞體->迭代模擬場景資料（計算一幀並輸出資料）
int main(int argc, char** argv)
{
    ///-----includes_end-----
 


    ///-----initialization_start-----

    // 建立碰撞配置物件以及碰撞排程器物件,使我們可以再各個階段嘗試不同的演算法組合,目的是使用不同的演算法和測試相同的碰撞
    // 碰撞配置
    ///collision configuration contains default setup for memory, collision setup. Advanced users can create their own configuration.
    btDefaultCollisionConfiguration* collisionConfiguration = new btDefaultCollisionConfiguration();

    // 碰撞排程
    ///use the default collision dispatcher. For parallel processing you can use a diffent dispatcher (see Extras/BulletMultiThreaded)
    btCollisionDispatcher* dispatcher = new btCollisionDispatcher(collisionConfiguration);

    // btDbvtBroadphase用來執行快速碰撞檢測    目的是儘量的剔除沒有相互作用的物件對
    ///btDbvtBroadphase is a good general purpose broadphase. You can also try out btAxis3Sweep.
    btBroadphaseInterface* overlappingPairCache = new btDbvtBroadphase();

    // 實際上的物理模擬器 
    // 建立解算器，用於求解約束方程。得到物體在重力等作用下的最終位置的
    ///the default constraint solver. For parallel processing you can use a different solver (see Extras/BulletMultiThreaded)
    btSequentialImpulseConstraintSolver* solver = new btSequentialImpulseConstraintSolver;

    // 獨立場景動態世界
    btDiscreteDynamicsWorld* dynamicsWorld = new btDiscreteDynamicsWorld(
                dispatcher, overlappingPairCache, solver, collisionConfiguration);

    dynamicsWorld->setGravity(btVector3(0, -10, 0));        // 設定重力加速度 Y向下

    ///-----initialization_end-----

    //keep track of the shapes, we release memory at exit.
    //make sure to re-use collision shapes among rigid bodies whenever possible!
    btAlignedObjectArray<btCollisionShape*> collisionShapes;

    ///create a few basic rigid bodies

    //建立一個地面,並加入到場景世界中
    //the ground is a cube of side 100 at position y = -56.
    //the sphere will hit it at y = -6, with center at -5
    {
        btCollisionShape* groundShape = new btBoxShape(btVector3(btScalar(50.), btScalar(50.), btScalar(50.))); // 長方體

        collisionShapes.push_back(groundShape);

        btTransform groundTransform;
        groundTransform.setIdentity();
        groundTransform.setOrigin(btVector3(0, -56, 0));        // 設定原點位置

        btScalar mass(0.);      // 質量

        //rigidbody is dynamic if and only if mass is non zero, otherwise static
        bool isDynamic = (mass != 0.f);

        btVector3 localInertia(0, 0, 0);        // 慣性
        if (isDynamic)
            groundShape->calculateLocalInertia(mass, localInertia); //通過質量，這個函式計算出運動物體的慣性

        // 運動狀態
        //using motionstate is optional, it provides interpolation capabilities, and only synchronizes 'active' objects
        btDefaultMotionState* myMotionState = new btDefaultMotionState(groundTransform);
        // 剛體構造資訊
        btRigidBody::btRigidBodyConstructionInfo  rbInfo(mass, myMotionState, groundShape, localInertia);
        // 剛體
        btRigidBody* body = new btRigidBody(rbInfo);

        // 將剛體新增至動態世界中
        //add the body to the dynamics world
        dynamicsWorld->addRigidBody(body);
    }

    {
        //建立一個球體,並加入到場景世界中
        //create a dynamic rigidbody

        //btCollisionShape* colShape = new btBoxShape(btVector3(1,1,1));
        btCollisionShape* colShape = new btSphereShape(btScalar(1.));       // 球體 半徑為1
        collisionShapes.push_back(colShape);

        /// Create Dynamic Objects
        btTransform startTransform;
        startTransform.setIdentity();
        startTransform.setOrigin(btVector3(2, 10, 0));

        btScalar mass(1.f);     // 質量

        //rigidbody is dynamic if and only if mass is non zero, otherwise static
        bool isDynamic = (mass != 0.f);

        btVector3 localInertia(0,  0, 0);       // 慣性
        if (isDynamic)
            colShape->calculateLocalInertia(mass, localInertia); //通過質量，這個函式計算出運動物體的慣性

        //using motionstate is recommended, it provides interpolation capabilities, and only synchronizes 'active' objects
        btDefaultMotionState* myMotionState = new btDefaultMotionState(startTransform);
        btRigidBody::btRigidBodyConstructionInfo rbInfo(mass, myMotionState, colShape, localInertia);
        btRigidBody* body = new btRigidBody(rbInfo);

        dynamicsWorld->addRigidBody(body);
    }

    /// Do some simulation
    int i = 0;
    // 步進模擬
    ///-----stepsimulation_start-----
    for (i = 0; i < 150; i++)
    {
        dynamicsWorld->stepSimulation(1.f / 5.f, 10);       // 模擬運動  每次進行物理模擬運算的時間間隔  每次能響應的最大step數

        //print positions of all objects
        for (int j = dynamicsWorld->getNumCollisionObjects() - 1; j >= 0; j--)
        {
            btCollisionObject* obj = dynamicsWorld->getCollisionObjectArray()[j];
            btRigidBody* body = btRigidBody::upcast(obj);
            btTransform trans;
            if (body && body->getMotionState())
            {
                body->getMotionState()->getWorldTransform(trans);
            }
            else
            {
                trans = obj->getWorldTransform();
            }
            printf("world pos object %d = %f,%f,%f\n", j, 
                float(trans.getOrigin().getX()), float(trans.getOrigin().getY()), float(trans.getOrigin().getZ()));
        }
        printf(" \n");
    }

    ///-----stepsimulation_end-----

    //cleanup in the reverse order of creation/initialization

    ///-----cleanup_start-----

    //清理動態世界裡的剛體
    //remove the rigidbodies from the dynamics world and delete them
    for (i = dynamicsWorld->getNumCollisionObjects() - 1; i >= 0; i--)
    {
        btCollisionObject* obj = dynamicsWorld->getCollisionObjectArray()[i];
        btRigidBody* body = btRigidBody::upcast(obj);
        if (body && body->getMotionState())
        {
            delete body->getMotionState();
        }
        dynamicsWorld->removeCollisionObject(obj);
        delete obj;
    }

    //清理碰撞形狀
    //delete collision shapes
    for (int j = 0; j < collisionShapes.size(); j++)
    {
        btCollisionShape* shape = collisionShapes[j];
        collisionShapes[j] = 0;
        delete shape;
    }

    //清理動態世界
    //delete dynamics world
    delete dynamicsWorld;

    //清理求解器
    //delete solver
    delete solver;

    //清理粗測階段
    //delete broadphase
    delete overlappingPairCache;

    //清理排程
    //delete dispatcher
    delete dispatcher;

    delete collisionConfiguration;

    //next line is optional: it will be cleared by the destructor when the array goes out of scope
    collisionShapes.clear();
}