Fixed ClippingNode stencil needing global z set manually (#1831)

This bug has existed since the Cocos2d-x 3.x days. If you set the global z order of a ClippingNode to anything other than the default value, then the ClippingNode fails to clip anything unless the global z order is also set for the Stencil of that ClippingNode. This change makes the ClippingNode._stencil's global z order to follow the ClippingNode's. (Note: you could still manually set the global z order of the stencil as desired to break the clipping. But now the default behavior works correctly and the way one would expect.)

core/2d/ClippingNode.cpp

@@ -227,6 +227,16 @@ void ClippingNode::visit(Renderer* renderer, const Mat4& parentTransform, uint32
     _director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
 }
 
+void ClippingNode::setGlobalZOrder(float globalZOrder)
+{
+    Node::setGlobalZOrder(globalZOrder);
+
+    if (_stencil) {
+        // Make sure our stencil stays on the same globalZOrder:
+        _stencil->setGlobalZOrder(globalZOrder);
+    }
+}
+
 void ClippingNode::setCameraMask(unsigned short mask, bool applyChildren)
 {
     Node::setCameraMask(mask, applyChildren);
@@ -279,6 +289,9 @@ void ClippingNode::setStencil(Node* stencil)
 
     if (_stencil != nullptr)
     {
+        // Make sure our stencil stays on the same globalZOrder:
+        _stencil->setGlobalZOrder(getGlobalZOrder());
+
         _originalStencilProgramState[_stencil] = _stencil->getProgramState();
         auto& children                         = _stencil->getChildren();
         for (const auto& child : children)

core/2d/ClippingNode.h

@@ -3,6 +3,7 @@
  * Copyright (c) 2012      cocos2d-x.org
  * Copyright (c) 2013-2016 Chukong Technologies Inc.
  * Copyright (c) 2017-2018 Xiamen Yaji Software Co., Ltd.
+ * Copyright (c) 2019-present Axmol Engine contributors (see AUTHORS.md).
  *
  * https://axmolengine.github.io/
  *
@@ -133,6 +134,8 @@ class AX_DLL ClippingNode : public Node
     virtual void onExit() override;
     virtual void visit(Renderer* renderer, const Mat4& parentTransform, uint32_t parentFlags) override;
 
+    virtual void setGlobalZOrder(float globalZOrder) override;
+
     virtual void setCameraMask(unsigned short mask, bool applyChildren = true) override;
 
     ClippingNode();