cocos2dx v3.x box2d DrawDebugData 后置问题

.众所周知, box2d的DrawDebugData函数绘制默认不是放在最前面的, 为了达到这个要求, v2版代码很简单

v2:

void Box2dManager::draw(){
    ccGLEnableVertexAttribs( kCCVertexAttribFlag_Position );
    kmGLPushMatrix();
    box2dWorld->DrawDebugData();
    kmGLPopMatrix();
}
           

v3:

v3版找了很久, 貌似研究的人不多, 不过找的过程中, 有人分析v3为了提高性能, 将v2那种单独渲染变成了集中渲染, 在draw中并不马上执行渲染, 这时候使用代码:

void Box2dManager::draw(Renderer *renderer, const Mat4& transform, uint32_t flags){
    GL::enableVertexAttribs( GL::VERTEX_ATTRIB_FLAG_POSITION );
    Director::getInstance()->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
    box2dWorld->DrawDebugData();
    Director::getInstance()->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
}
           

这个写法是完全从v2过度过来的, 但很遗憾, 并没有实现该有的功能

而根据v3方式把要渲染的顺序加入到渲染序列中, 通过调用onDraw来进行上面的代码, 这时候才能有效的让渲染悬浮在其他sprite之上

void Box2dManager::draw(Renderer *renderer, const Mat4& transform, uint32_t flags){
    super::draw(renderer, transform, _transformUpdated);
    GL::enableVertexAttribs( cocos2d::GL::VERTEX_ATTRIB_FLAG_POSITION );
    Director* director = Director::getInstance();
    CCASSERT(nullptr != director, "Director is null when seting matrix stack");
    director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
    _modelViewMV = director->getMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
    _customCommand.init(_globalZOrder);
    _customCommand.func = CC_CALLBACK_0(Box2dManager::onDraw, this);
    renderer->addCommand(&_customCommand);
    director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
}

void Box2dManager::onDraw() {
    Director* director = Director::getInstance();
    CCASSERT(nullptr != director, "Director is null when seting matrix stack");
    Mat4 oldMV;
    oldMV = director->getMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
    director->loadMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW, _modelViewMV);
    box2dWorld->DrawDebugData();
    director->loadMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW, oldMV);
}
           

参考:

Box2d debug drawing for cocos2d-x 3.0

B2DebugDrawLayer attachment

Cocos2d-x 3.2的渲染流程

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