DrawNode add isolate flag (#19056)

* add isolate flag

* add comment for DrawNode::visit

* add modifier: const/virtual

* update comment & change initializer

cocos/2d/CCDrawNode.cpp

@@ -101,25 +101,7 @@ static inline Tex2F __t(const Vec2 &v)
 // implementation of DrawNode
 
 DrawNode::DrawNode(GLfloat lineWidth)
-: _vao(0)
-, _vbo(0)
-, _vaoGLPoint(0)
-, _vboGLPoint(0)
-, _vaoGLLine(0)
-, _vboGLLine(0)
-, _bufferCapacity(0)
-, _bufferCount(0)
-, _buffer(nullptr)
-, _bufferCapacityGLPoint(0)
-, _bufferCountGLPoint(0)
-, _bufferGLPoint(nullptr)
-, _bufferCapacityGLLine(0)
-, _bufferCountGLLine(0)
-, _bufferGLLine(nullptr)
-, _dirty(false)
-, _dirtyGLPoint(false)
-, _dirtyGLLine(false)
-, _lineWidth(lineWidth)
+: _lineWidth(lineWidth)
 , _defaultLineWidth(lineWidth)
 {
     _blendFunc = BlendFunc::ALPHA_PREMULTIPLIED;
@@ -957,5 +939,17 @@ GLfloat DrawNode::getLineWidth()
     return this->_lineWidth;
 }
 
+void DrawNode::visit(Renderer* renderer, const Mat4 &parentTransform, uint32_t parentFlags)
+{
+    if (_isolated)
+    {
+        //ignore `parentTransform` from parent
+        Node::visit(renderer, Mat4::IDENTITY, parentFlags);
+    }
+    else
+    {
+        Node::visit(renderer, parentTransform, parentFlags);
+    }
+}
 
 NS_CC_END

cocos/2d/CCDrawNode.h

@@ -313,12 +313,22 @@ public:
     
     // Overrides
     virtual void draw(Renderer *renderer, const Mat4 &transform, uint32_t flags) override;
+
+    virtual void visit(Renderer* renderer, const Mat4 &parentTransform, uint32_t parentFlags) override;
     
     void setLineWidth(GLfloat lineWidth);
 
     // Get CocosStudio guide lines width.
     GLfloat getLineWidth();
 
+    /**
+    * When isolated is set, the position of the node is no longer affected by parent nodes.
+    * Which means it will be drawn just like a root node.
+    */
+    void setIsolated(bool isolated) { _isolated = isolated; }
+
+    bool isIsolated() const { return _isolated; }
+
 CC_CONSTRUCTOR_ACCESS:
     DrawNode(GLfloat lineWidth = DEFAULT_LINE_WIDTH);
     virtual ~DrawNode();
@@ -331,39 +341,40 @@ protected:
 
     void setupBuffer();
 
-    GLuint      _vao;
-    GLuint      _vbo;
-    GLuint      _vaoGLPoint;
-    GLuint      _vboGLPoint;
-    GLuint      _vaoGLLine;
-    GLuint      _vboGLLine;
+    GLuint      _vao = 0;
+    GLuint      _vbo = 0;
+    GLuint      _vaoGLPoint = 0;
+    GLuint      _vboGLPoint = 0;
+    GLuint      _vaoGLLine = 0;
+    GLuint      _vboGLLine = 0;
 
-    int         _bufferCapacity;
-    GLsizei     _bufferCount;
-    V2F_C4B_T2F *_buffer;
+    int         _bufferCapacity = 0;
+    GLsizei     _bufferCount = 0;
+    V2F_C4B_T2F *_buffer = nullptr;
     
-    int         _bufferCapacityGLPoint;
-    GLsizei     _bufferCountGLPoint;
-    V2F_C4B_T2F *_bufferGLPoint;
+    int         _bufferCapacityGLPoint = 0;
+    GLsizei     _bufferCountGLPoint = 0;
+    V2F_C4B_T2F *_bufferGLPoint = nullptr;
     Color4F     _pointColor;
-    int         _pointSize;
+    int         _pointSize = 0;
     
-    int         _bufferCapacityGLLine;
-    GLsizei     _bufferCountGLLine;
-    V2F_C4B_T2F *_bufferGLLine;
+    int         _bufferCapacityGLLine = 0;
+    GLsizei     _bufferCountGLLine = 0;
+    V2F_C4B_T2F *_bufferGLLine = nullptr;
 
     BlendFunc   _blendFunc;
     CustomCommand _customCommand;
     CustomCommand _customCommandGLPoint;
     CustomCommand _customCommandGLLine;
 
-    bool        _dirty;
-    bool        _dirtyGLPoint;
-    bool        _dirtyGLLine;
+    bool        _dirty = false;
+    bool        _dirtyGLPoint = false;
+    bool        _dirtyGLLine = false;
+    bool        _isolated = false;
     
-    GLfloat         _lineWidth;
+    GLfloat         _lineWidth = 0.0f;
 
-    GLfloat  _defaultLineWidth;
+    GLfloat  _defaultLineWidth = 0.0f;
 private:
     CC_DISALLOW_COPY_AND_ASSIGN(DrawNode);
 };

cocos/physics/CCPhysicsWorld.cpp

@@ -270,6 +270,7 @@ void PhysicsWorld::debugDraw()
     if (_debugDraw == nullptr)
     {
         _debugDraw = DrawNode::create();
+        _debugDraw->setIsolated(true);
         _debugDraw->retain();
         Director::getInstance()->getRunningScene()->addChild(_debugDraw);
     }