nodes: allow ignoring specific inputs for rendering

Also ignore sequence input on multicam

app/node/input/multicam/multicamnode.cpp

@@ -98,6 +98,11 @@ bool MultiCamNode::IsInputConnectedForRender(const QString &input, int element)
   }
 }
 
+QVector<QString> MultiCamNode::IgnoreInputsForRendering() const
+{
+  return {kSequenceInput};
+}
+
 void MultiCamNode::InputConnectedEvent(const QString &input, int element, Node *output)
 {
   if (input == kSequenceInput) {

app/node/input/multicam/multicamnode.h

@@ -60,6 +60,8 @@ public:
   virtual Node *GetConnectedRenderOutput(const QString& input, int element = -1) const override;
   virtual bool IsInputConnectedForRender(const QString& input, int element = -1) const override;
 
+  virtual QVector<QString> IgnoreInputsForRendering() const override;
+
 protected:
   virtual void InputConnectedEvent(const QString &input, int element, Node *output) override;
   virtual void InputDisconnectedEvent(const QString &input, int element, Node *output) override;

app/node/node.h

@@ -212,6 +212,11 @@ public:
     return input_ids_;
   }
 
+  virtual QVector<QString> IgnoreInputsForRendering() const
+  {
+    return QVector<QString>();
+  }
+
   class ActiveElements
   {
   public:

app/node/traverser.cpp

@@ -38,11 +38,16 @@ NodeValueDatabase NodeTraverser::GenerateDatabase(const Node* node, const TimeRa
   }
 
   // We need to insert tables into the database for each input
+  auto ignore = node->IgnoreInputsForRendering();
   foreach (const QString& input, node->inputs()) {
     if (IsCancelled()) {
       return NodeValueDatabase();
     }
 
+    if (ignore.contains(input)) {
+      continue;
+    }
+
     database.Insert(input, ProcessInput(node, input, range));
   }