box2d——1.tiles瓦片积木

【调试渲染】

将TestCpp里Box2DTestBed的GLES-Render.h/cpp加入到项目中。声明绘制变量：GLESDebugDrawmDebugDraw。

【创建世界】

	// 依据重力创建世界b2Vec2 gravity;gravity.Set(0.0f, -10.0f);mWorld = new b2World(gravity);// 设置调试渲染和碰撞侦听mWorld->SetDebugDraw(&mDebugDraw);mWorld->SetContactListener(this);// 创建地面身体b2BodyDef goundBodyDef;mGroundBody = mWorld->CreateBody(&goundBodyDef);// 设置物理更新函数schedule(schedule_selector(CTilesLayer::tick));

【创建物体】

	mFixtureCount = 0;b2Timer timer;// 创建静态的矩形(1个body多个shape、fixture){float32 a = 0.5f;b2BodyDef bd;bd.position.y = -a;b2Body* ground = mWorld->CreateBody(&bd);int32 N = 200;int32 M = 10;b2Vec2 position;position.y = 0.0f;for (int32 j = 0; j < M; ++j){position.x = -N * a;for (int32 i = 0; i < N; ++i){b2PolygonShape shape;shape.SetAsBox(a, a, position, 0.0f);ground->CreateFixture(&shape, 0.0f);++mFixtureCount;position.x += 2.0f * a;}position.y -= 2.0f * a;}}// 创建动态的矩形(一个shape多个body){float32 a = 0.5f;b2PolygonShape shape;shape.SetAsBox(a, a);b2Vec2 x(-7.0f, 0.75f);b2Vec2 y;b2Vec2 deltaX(0.5625f, 1.25f);b2Vec2 deltaY(1.125f, 0.0f);enum { e_count = 20 };for (int32 i = 0; i < e_count; ++i){y = x;for (int32 j = i; j < e_count; ++j){b2BodyDef bd;bd.type = b2_dynamicBody;bd.position = y;b2Body* body = mWorld->CreateBody(&bd);body->CreateFixture(&shape, 5.0f);++mFixtureCount;y += deltaY;}x += deltaX;}}

【设置物理显示】

	// 设置显示mTextLine = 30;setScale(15);setAnchorPoint( ccp(0,0) );CCSize screenSize = CCDirector::sharedDirector()->getWinSize();setPosition( ccp(screenSize.width/2, screenSize.height/3) );// 设置物理uint32 flags = 0;flags += b2Draw::e_shapeBit;flags += b2Draw::e_jointBit;mDebugDraw.SetFlags(flags);mWorld->SetWarmStarting(true);mWorld->SetContinuousPhysics(true);mWorld->SetSubStepping(false);

【绘制物理】

void CTilesLayer::draw()
{CCLayer::draw();ccGLEnableVertexAttribs( kCCVertexAttribFlag_Position );kmGLPushMatrix();// 绘制物理数据mWorld->DrawDebugData();kmGLPopMatrix();CHECK_GL_ERROR_DEBUG();
}

【更新物理】

void CTilesLayer::tick(float dt)
{// 显示const b2ContactManager& cm = mWorld->GetContactManager();int32 height = cm.m_broadPhase.GetTreeHeight();int32 leafCount = cm.m_broadPhase.GetProxyCount();int32 minimumNodeCount = 2 * leafCount - 1;float32 minimumHeight = ceilf(logf(float32(minimumNodeCount)) / logf(2.0f));mDebugDraw.DrawString(5, mTextLine, "dynamic tree height = %d, min = %d", height, int32(minimumHeight));mTextLine += 15;mWorld->Step(1/60.0f, 8, 3);mWorld->DrawDebugData();mDebugDraw.DrawString(5, mTextLine, "create time = %6.2f ms, fixture count = %d",mCreateTime, mFixtureCount);mTextLine += 15;}

【效果图和下载】