좌우가 연속되는 배경 횡스크롤

#define LAYER_BG_WIDTH 4096
#define LAYER_BG_HEIGHT 1024
#define LAYER_BG_BACK_TIME 120.0f //BG 기준 time

init()
{
//BG 영역
//BG repeat parameter
Texture2D::TexParams params;
params.minFilter = GL_NEAREST;
params.magFilter = GL_NEAREST;
params.wrapS = GL_REPEAT;
params.wrapT = GL_REPEAT;

//Rect영역은 texture의 좌상단부터 계산하는 점 유의
back = Sprite::create("bg/bg_base.png", Rect(0, 0, 768, LAYER_BG_HEIGHT));
back->getTexture()->setTexParameters(params);
back->setAnchorPoint(Vec2(0, 0));
back->setPosition(0, 0);
addChild(back, 0);
}

update(float delta)
{
//BG move
bgBackX += LAYER_BG_WIDTH / LAYER_BG_BACK_TIME * delta;
if (bgBackX >= LAYER_BG_WIDTH) bgBackX -= LAYER_BG_WIDTH;
back->setTextureRect(Rect(bgBackX, 0, 768, LAYER_BG_HEIGHT));
}