子节点的位置与父节点位置的关系
当父节点旋转时,子节点旋转,父节点缩放时,子节点缩放。其实里面的计算原理很简单,就是父节点矩阵乘以子节点矩阵得到最终矩阵。
相关代码如下:
Mat4 Node::getNodeToParentTransform()
{
updateMatrix();
return _model;
}
Mat4 Node::transform(const Mat4& parentTransform)
{
Mat4 ret = this->getNodeToParentTransform();
ret = parentTransform * ret;
return ret;
}
void Engine::drawScene()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//生成渲染指令
if(_SceneManager.size() > 0)
{
Scene * scene = _SceneManager.back();
scene->visit(Mat4(1.f));
}
//优化渲染队列
Renderer::getInstance()->visit();
//渲染到屏幕
Renderer::getInstance()->renderBatch();
if(_glView)
_glView->swapBuffers();
}
void Node::visit(const Mat4& parentMat4)
{
int i = 0;
if(!_children.empty())
{
sortAllChildren();
// draw children zOrder < 0
for(i = 0 ; i < _children.size(); i++ )
{
auto node = _children.at(i);
if ( node && node->getZOrder() < 0 )
node->visit(this->transform(parentMat4));
else
break;
}
// self draw
this->render(parentMat4);
for(auto it=_children.cbegin()+i; it != _children.cend(); ++it)
(*it)->visit(this->transform(parentMat4));
}
else
{
this->render(parentMat4);
}
}
void Sprite::render(const Mat4& parentMat4)
{
//updateMatrix();
updateColor();
_quadCommand.init(&_quad,_textureID,1,_blendFunc,this->transform(parentMat4));
Renderer::getInstance()->addQuadCommand(&_quadCommand);
}