Cocos2d-x3.1中ClippingNode的使用实例

#include "2d/CCNode.h"//用到节点头文件和OPENGL深度缓冲定义头文件
#include "CCGL.h"
#include "renderer/CCGroupCommand.h"//用到GroupCommand和CustomCommand渲染
#include "renderer/CCCustomCommand.h"

NS_CC_BEGIN

/** ClippingNode is a subclass of Node.
 It draws its content (childs) clipped using a stencil.
 The stencil is an other Node that will not be drawn.
 The clipping is done using the alpha part of the stencil (adjusted with an alphaThreshold).
 */
class CC_DLL ClippingNode : public Node
{
public:
 /** Creates and initializes a clipping node without a stencil.
 */
 static ClippingNode* create();//静态创建对象
 
 /** Creates and initializes a clipping node with an other node as its stencil.
 The stencil node will be retained.
 */
 static ClippingNode* create(Node *stencil);//用模板创建裁剪节点

 /** The Node to use as a stencil to do the clipping.
 The stencil node will be retained.
 This default to nil.
 */
 Node* getStencil() const;//获取节点模板
 void setStencil(Node *stencil);//设置节点模板
 
 /** The alpha threshold.
 The content is drawn only where the stencil have pixel with alpha greater than the alphaThreshold.
 Should be a float between 0 and 1.
 This default to 1 (so alpha test is disabled).
 *///ALPHA测试参考值，用于进行ALPHA测试比较，一般比较算法为小于此值的像素会直接被舍弃，这样就实现了图像的镂空
 GLfloat getAlphaThreshold() const;//获取ALPHT的测试参考值
 void setAlphaThreshold(GLfloat alphaThreshold);//设置ALPHA的测试参考值
 
 /** Inverted. If this is set to true,
 the stencil is inverted, so the content is drawn where the stencil is NOT drawn.
 This default to false.
 */
 bool isInverted() const;//获取遮罩运算是否取反设置
 void setInverted(bool inverted);//设置遮罩运算取反

 // Overrides//继承的函数
 /**
 * @js NA
 * @lua NA
 */
 virtual void onEnter() override;
 /**
 * @js NA
 * @lua NA
 */
 virtual void onEnterTransitionDidFinish() override;
 /**
 * @js NA
 * @lua NA
 */
 virtual void onExitTransitionDidStart() override;
 /**
 * @js NA
 * @lua NA
 */
 virtual void onExit() override;
 virtual void visit(Renderer *renderer, const Mat4 &parentTransform, bool parentTransformUpdated) override;
 
CC_CONSTRUCTOR_ACCESS:
 ClippingNode();
 
 /**
 * @js NA
 * @lua NA
 */
 virtual ~ClippingNode();

 /** Initializes a clipping node without a stencil.
 */
 virtual bool init();
 
 /** Initializes a clipping node with an other node as its stencil.
 The stencil node will be retained, and its parent will be set to this clipping node.
 */
 virtual bool init(Node *stencil);

protected:
 /**draw fullscreen quad to clear stencil bits
 */
 void drawFullScreenQuadClearStencil();

 Node* _stencil;
 GLfloat _alphaThreshold;
 bool _inverted;

 //renderData and callback
 void onBeforeVisit();
 void onAfterDrawStencil();
 void onAfterVisit();

 GLboolean _currentStencilEnabled;
 GLuint _currentStencilWriteMask;
 GLenum _currentStencilFunc;
 GLint _currentStencilRef;
 GLuint _currentStencilValueMask;
 GLenum _currentStencilFail;
 GLenum _currentStencilPassDepthFail;
 GLenum _currentStencilPassDepthPass;
 GLboolean _currentDepthWriteMask;

 GLboolean _currentAlphaTestEnabled;
 GLenum _currentAlphaTestFunc;
 GLclampf _currentAlphaTestRef;

 GLint _mask_layer_le;
 
 GroupCommand _groupCommand;
 CustomCommand _beforeVisitCmd;
 CustomCommand _afterDrawStencilCmd;
 CustomCommand _afterVisitCmd;

private:
 CC_DISALLOW_COPY_AND_ASSIGN(ClippingNode);
};

NS_CC_END

class NewClippingNode : public Layer
{
public:
 CREATE_FUNC(NewClippingNode);
 virtual bool init();
};