描画（DrawPrimitives）

• Layer 派生クラスで、draw() を再実装し、onDraw() を呼ぶようにする。

#include "renderer/CCRenderer.h"
USING_NS_CC;
class Hoge : public cocos2d::Layer
{
    .....
public:
    virtual void draw(Renderer *renderer, const Mat4 &transform, bool transformUpdated) override;
protected:
    void onDraw(const Mat4 &transform, bool transformUpdated);
    CustomCommand _customCommand;
};

void Hoge::draw(Renderer *renderer, const Mat4 &transform, bool transformUpdated)
{
    _customCommand.init(_globalZOrder);
    _customCommand.func = CC_CALLBACK_0(Hoge::onDraw, this, transform, transformUpdated);
    renderer->addCommand(&_customCommand);
}

void HelloWorld::onDraw(const Mat4 &transform, bool transformUpdated)
{
    Director* director = Director::getInstance();
    CCASSERT(nullptr != director, "Director is null when seting matrix stack");
    director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
    director->loadMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW, transform);

    //DrawPrimitives::drawLine(...); 等を使って描画

    //end draw
    director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
}