Handle Topological Value Changes

source/MaterialXGenShader/Util.cpp

@@ -588,6 +588,47 @@ bool hasElementAttributes(OutputPtr output, const StringVec& attributes)
     return false;
 }
 
+bool inputChangeRequiresShaderGen(InputPtr input, const string& target)
+{
+    ElementPtr inputParent = input ? input->getParent() : nullptr;
+    if (inputParent)
+    {
+        NodePtr node = inputParent->asA<Node>();
+        if (node)
+        {
+            NodeDefPtr nodeDef = node->getNodeDef(target);
+            // All conditional nodes are considered to change the topology of the shader graph
+            if (nodeDef->getNodeGroup() == NodeDef::CONDITIONAL_NODE_GROUP)
+            {
+                return true;
+            }
+        }
+
+        // This is an interface input so find what it's connected to.
+        NodeGraphPtr nodeGraph = inputParent->asA<NodeGraph>();
+        if (nodeGraph)
+        {
+            const std::string& inputName = input->getName();
+            for (NodePtr graphNode : nodeGraph->getNodes())
+            {
+                for (InputPtr graphNodeInput : graphNode->getActiveInputs())
+                {
+                    if (graphNodeInput->getInterfaceName() == inputName)
+                    {
+                        NodeDefPtr nodeDef = graphNode->getNodeDef();
+                        // All conditional nodes are considered to change the topology of the shader graph
+                        if (nodeDef->getNodeGroup() == NodeDef::CONDITIONAL_NODE_GROUP)
+                        {
+                            return true;
+                        }
+                    }
+                }
+            }
+        }
+    }
+    return false;
+}
+
 void findRenderableMaterialNodes(ConstDocumentPtr doc, vector<TypedElementPtr>& elements, bool, std::unordered_set<ElementPtr>&)
 {
     elements = findRenderableMaterialNodes(doc);

source/MaterialXGenShader/Util.h

@@ -86,6 +86,14 @@ MX_GENSHADER_API NodePtr connectsToWorldSpaceNode(OutputPtr output);
 /// @param attributes Attributes to test for
 MX_GENSHADER_API bool hasElementAttributes(OutputPtr output, const StringVec& attributes);
 
+/// Returns true if a value change on a given input could require a shader compilation as it changes the output shader
+/// graph configuration (i.e. is a topological change). 
+/// The current criteria is:
+/// * any input on a conditional node is considered to modify the topology of the output shader graph.
+/// @param input Input to test
+/// @param target An optional target name which may be used as part of the criteria
+MX_GENSHADER_API bool inputChangeRequiresShaderGen(InputPtr input, const string& target = EMPTY_STRING);
+
 //
 // These are deprecated wrappers for older versions of the function interfaces in this module.
 // Clients using these interfaces should update them to the latest API.

source/MaterialXGraphEditor/Graph.cpp

@@ -722,6 +722,7 @@ void Graph::setRenderMaterial(UiNodePtr node)
             _currRenderNode = node;
             _frameCount = ImGui::GetFrameCount();
             _renderer->setMaterialCompilation(true);
+            _shaderPopup = true;
         }
     }
 
@@ -832,6 +833,7 @@ void Graph::setRenderMaterial(UiNodePtr node)
                         _currRenderNode = uiNode;
                         _frameCount = ImGui::GetFrameCount();
                         _renderer->setMaterialCompilation(true);
+                        _shaderPopup = true;
                     }
                     break;
                 }
@@ -869,20 +871,13 @@ void Graph::updateMaterials(mx::InputPtr input, mx::ValuePtr value)
     {
         if (!input)
         {
-            mx::ElementPtr elem = nullptr;
-            {
-                elem = _graphDoc->getDescendant(renderablePath);
-            }
+            mx::ElementPtr elem = _graphDoc->getDescendant(renderablePath);
             mx::TypedElementPtr typedElem = elem ? elem->asA<mx::TypedElement>() : nullptr;
             _renderer->updateMaterials(typedElem);
         }
         else
         {
             std::string name = input->getNamePath();
-
-            // Note that if there is a topogical change due to
-            // this value change or a transparency change, then
-            // this is not currently caught here.
             _renderer->getMaterials()[0]->modifyUniform(name, value);
         }
     }
@@ -895,6 +890,8 @@ void Graph::setConstant(UiNodePtr node, mx::InputPtr& input, const mx::UIPropert
     mx::ValuePtr minVal = uiProperties.uiMin;
     mx::ValuePtr maxVal = uiProperties.uiMax;
 
+    bool updateMaterialRequired = false;
+
     // If input is a float set the float slider UI to the value
     if (input->getType() == "float")
     {
@@ -914,7 +911,7 @@ void Graph::setConstant(UiNodePtr node, mx::InputPtr& input, const mx::UIPropert
             {
                 addNodeInput(_currUiNode, input);
                 input->setValue(temp, input->getType());
-                updateMaterials(input, input->getValue());
+                updateMaterialRequired = true;
             }
         }
     }
@@ -934,7 +931,7 @@ void Graph::setConstant(UiNodePtr node, mx::InputPtr& input, const mx::UIPropert
             {
                 addNodeInput(_currUiNode, input);
                 input->setValue(temp, input->getType());
-                updateMaterials(input, input->getValue());
+                updateMaterialRequired = true;
             }
         }
     }
@@ -958,7 +955,7 @@ void Graph::setConstant(UiNodePtr node, mx::InputPtr& input, const mx::UIPropert
             {
                 addNodeInput(_currUiNode, input);
                 input->setValue(temp, input->getType());
-                updateMaterials(input, input->getValue());
+                updateMaterialRequired = true;
             }
         }
     }
@@ -984,7 +981,7 @@ void Graph::setConstant(UiNodePtr node, mx::InputPtr& input, const mx::UIPropert
             {
                 addNodeInput(_currUiNode, input);
                 input->setValue(temp, input->getType());
-                updateMaterials(input, input->getValue());
+                updateMaterialRequired = true;
             }
         }
     }
@@ -1004,7 +1001,7 @@ void Graph::setConstant(UiNodePtr node, mx::InputPtr& input, const mx::UIPropert
             {
                 addNodeInput(_currUiNode, input);
                 input->setValue(temp, input->getType());
-                updateMaterials(input, input->getValue());
+                updateMaterialRequired = true;
             }
         }
     }
@@ -1024,7 +1021,7 @@ void Graph::setConstant(UiNodePtr node, mx::InputPtr& input, const mx::UIPropert
             {
                 addNodeInput(_currUiNode, input);
                 input->setValue(temp, input->getType());
-                updateMaterials(input, input->getValue());
+                updateMaterialRequired = true;
             }
         }
     }
@@ -1044,7 +1041,7 @@ void Graph::setConstant(UiNodePtr node, mx::InputPtr& input, const mx::UIPropert
             {
                 addNodeInput(_currUiNode, input);
                 input->setValue(temp, input->getType());
-                updateMaterials(input, input->getValue());
+                updateMaterialRequired = true;
             }
         }
     }
@@ -1061,7 +1058,7 @@ void Graph::setConstant(UiNodePtr node, mx::InputPtr& input, const mx::UIPropert
             {
                 addNodeInput(_currUiNode, input);
                 input->setValue(temp, input->getType());
-                updateMaterials();
+                updateMaterialRequired = true;
             }
         }
     }
@@ -1110,7 +1107,7 @@ void Graph::setConstant(UiNodePtr node, mx::InputPtr& input, const mx::UIPropert
                 addNodeInput(_currUiNode, input);
                 input->setValueString(temp);
                 input->setValue(temp, input->getType());
-                updateMaterials();
+                updateMaterialRequired = true;
             }
         }
     }
@@ -1127,12 +1124,27 @@ void Graph::setConstant(UiNodePtr node, mx::InputPtr& input, const mx::UIPropert
             {
                 addNodeInput(_currUiNode, input);
                 input->setValue(temp, input->getType());
-                updateMaterials(input, input->getValue());
+                updateMaterialRequired = true;
             }
         }
     }
 
     ImGui::PopItemWidth();
+
+    if (updateMaterialRequired)
+    {
+        if (!_renderer->getMaterialCompilation() && mx::inputChangeRequiresShaderGen(input))
+        {
+            _frameCount = ImGui::GetFrameCount();
+            _renderer->setMaterialCompilation(true);
+            _shaderPopup = false;
+        }
+        else
+        {
+            updateMaterials(input, input->getValue());
+        }
+    }
+
 }
 
 void Graph::setUiNodeInfo(UiNodePtr node, const std::string& type, const std::string& category)
@@ -3724,6 +3736,11 @@ void Graph::readOnlyPopup()
 
 void Graph::shaderPopup()
 {
+    if (!_shaderPopup)
+    {
+        return;
+    }
+
     if (_renderer->getMaterialCompilation())
     {
         ImGui::SetNextWindowPos(ImVec2((float) _renderer->getViewWidth() - 135, (float) _renderer->getViewHeight() + 5));
@@ -4162,8 +4179,11 @@ void Graph::drawGraph(ImVec2 mousePos)
     shaderPopup();
     if (ImGui::GetFrameCount() == (_frameCount + 2))
     {
-        updateMaterials();
-        _renderer->setMaterialCompilation(false);
+        if (_renderer->getMaterialCompilation())
+        {
+            updateMaterials();
+            _renderer->setMaterialCompilation(false);
+        }
     }
 
     ed::Suspend();

source/PyMaterialX/PyMaterialXGenShader/PyUtil.cpp

@@ -36,4 +36,5 @@ void bindPyUtil(py::module& mod)
     mod.def("getUdimScaleAndOffset", &mx::getUdimScaleAndOffset);
     mod.def("connectsToWorldSpaceNode", &mx::connectsToWorldSpaceNode);
     mod.def("hasElementAttributes", &mx::hasElementAttributes);
+    mod.def("inputChangeRequiresShaderGen", &mx::inputChangeRequiresShaderGen);
 }