Global Status Overview

The only way to change the global state in V4 is through the Renderer object. For example, turn on the depth test. Next, we will analyze how to set the global state and fixed pipeline functions through the Renderer.

clear attachment

Specify the buffer to be emptied by ClearFlag

_renderer->clear(ClearFlag::ALL, // Clear color, depth and stencil buffer.
  _clearColor, // the color value used when the color buffer is cleared
  1, // the depth value used when the depth buffer is cleared
  0, // the index used when the stencil buffer is cleared
  -10000.0); // specify the globalOrder value

Depth Test

In the initialization function, set a callback function to save and restore the original global state.

void Demo::init()
{
    _customCommand.setBeforeCallback(CC_CALLBACK_0(Demo::onBeforeDraw, this));
    _customCommand.setAfterCallback(CC_CALLBACK_0(Demo::onAfterDraw, this));
}

• onBeforeDraw

  void Demo::onBeforeDraw()
  {
    auto renderer = Director::getInstance()->getRenderer();
    // manually save the global state
    _oldDepthTestEnabled = renderer->getDepthTest();
    _oldDepthWriteMask = renderer->getDepthWrite();
    _oldDepthCmpFunc = renderer->getDepthCompareFunction();
  ... // store other global state, such as cull mode.
    renderer->setDepthTest(true);
    renderer->setDepthWrite(true);
    renderer->setDepthCompareFunction(backend::CompareFunction::LESS_EQUAL);
    ... //do additional operations.
  }
  

• onAfterDraw

  void Demo::onAfterDraw()
  {
    auto renderer = Director::getInstance()->getRenderer();
    // manually restore the global state
    renderer->setDepthTest(_oldDepthTestEnabled);
    renderer->setDepthWrite(_oldDepthWriteMask);
    renderer->setDepthCompareFunction(_oldDepthCmpFunc);
    ...restore other global state
  }
  

Stencil Test

As with Depth Test, set the callback function to save and restore the original global state.

void Demo::init()
{
    _customCommand.setBeforeCallback(CC_CALLBACK_0(Demo::onBeforeDraw, this));
    _customCommand.setAfterCallback(CC_CALLBACK_0(Demo::onAfterDraw, this));
}

• onBeforeDraw

  void Demo::onBeforeDraw()
  {
      auto renderer = Director::getInstance()->getRenderer();
      // manually save the stencil state
      _oldStencilEnabled = renderer->getStencilTest();
      _oldStencilWriteMask = renderer->getStencilWriteMask();
      _oldStencilFunc = renderer->getStencilCompareFunction();
      _oldStencilRef = renderer->getStencilReferenceValue();
      _oldStencilReadMask = renderer->getStencilReadMask();
      _oldStencilFail = renderer->getStencilFailureOperation();
      _oldStencilPassDepthFail = renderer->getStencilPassDepthFailureOperation();
      _oldStencilPassDepthPass = renderer->getStencilDepthPassOperation();
    ... // save other global states
  
      // set stencil states
      renderer->setStencilTest(true);
      renderer->setStencilWriteMask(_writeMask);
      renderer->setStencilCompareFunction(_compareFunction,
                                          _refValue,
                                          _readMask);
      renderer->setStencilOperation(_sfailOp,
                                    _zfailOp,
                                    _zpassOp);
  }
  

• onAfterDraw

  void StencilStateManager::onAfterVisit()
  {
      // manually restore the stencil state
      auto renderer = Director::getInstance()->getRenderer();
      renderer->setStencilCompareFunction(_oldStencilFunc,
                                          _oldStencilRef,
                                          _oldStencilReadMask);
  
      renderer->setStencilOperation(_oldFail,
                                    _oldPassDepthFail,
                                    _oldPassDepthPass);
  
      renderer->setStencilWriteMask(_oldStencilWriteMask);
      if (!_oldStencilEnabled)
      {
          renderer->setStencilTest(false);
      }
  }
  

Viewport

// save current viewport
_oldViewport = renderer->getViewport(); 
renderer->setViewPort(viewport.origin.x, 
                      viewport.origin.y, 
                      viewport.size.width, 
                      viewport.size.height);

Scissor

//save scissor test status
_oldScissorTest = renderer->getScissorTest();
_oldScissorRect = renderer->getScissorRect();

//set scissor test
renderer->setScissorTest(true);
renderer->setScissorRect(x, y, width, height);

//restore scissor test status
renderer->setScissorTest(_oldScissorTest);
renderer->setScissorRect(_oldScissorRect.x, 
                         _oldScissorRect.y, 
                         _oldScissorRect.width, 
                         _oldScissorRect.height);

CullMode

_oldCullMode = renderer->getCullMode();
renderer->setCullMode(cullMode);

Winding

_oldWinding = renderer->getWinding();
renderer->setWinding(winding);

Set render target

Set callbacks to execute some operations before start and after finish rendered to a texture.

void Demo::init()
{
      _beginCallbackCommand.func = CC_CALLBACK_0(RenderTexture::onBegin, this);
    _endCallbackCommand.func = CC_CALLBACK_0(RenderTexture::onEnd, this);
}

• onBegin

  //save attachemnt status
  _oldColorAttachment = renderer->getColorAttachment();
  _oldDepthAttachment = renderer->getDepthAttachment();
  _oldStencilAttachment = renderer->getStencilAttachment();
  _oldRenderTargetFlag = renderer->getRenderTargetFlag();
  
  renderer->setRenderTarget(_renderTargetFlags, // indicate which attachment to be replaced 
                            _texture2D, 
                            _depthTexture, 
                            _stencilTexture);
  

• onEnd

  renderer->setRenderTarget(_oldRenderTargetFlag, 
                            _oldColorAttachment, 
                            _oldDepthAttachment, 
                            _oldStencilAttachment);