sweeping node graph changes for new rendering pipeline

The new rendering pipeline strives to simplify the nodes themselves as much
as possible and move much of the logic to an external rendering engine. This
change removes all of the responsibilities that no longer belong to the
nodes themselves and will soon be folded into the renderer.

app/node/output.cpp

@@ -23,8 +23,7 @@
 #include "node/node.h"
 
 NodeOutput::NodeOutput(const QString &id) :
-  NodeParam(id),
-  linked_input_(nullptr)
+  NodeParam(id)
 {
 }
 
@@ -33,40 +32,33 @@ NodeParam::Type NodeOutput::type()
   return kOutput;
 }
 
-QVariant NodeOutput::get_value(const rational& in, const rational& out)
+QVariant NodeOutput::get_realtime_value()
 {
-  mutex_.lock();
+  parent()->LockProcessing();
 
-  QVariant v;
+  QVariant v = parent()->Value(this);
 
-  if (in_ != in || out_ != out || !value_caching_) {
-    // Update the value
-    value_ = parent()->Run(this, in, out);
-
-    in_ = in;
-    out_ = out;
-  }
-
-  v = value_;
-
-  mutex_.unlock();
+  parent()->UnlockProcessing();
 
   return v;
 }
 
-void NodeOutput::push_value(const QVariant &v, const rational &in, const rational &out)
+bool NodeOutput::has_cached_value(const TimeRange &time)
 {
-  value_ = v;
-  in_ = in;
-  out_ = out;
+  return cached_values_.contains(time);
 }
 
-NodeInput *NodeOutput::linked_input()
+QVariant NodeOutput::get_cached_value(const TimeRange &time)
 {
-  return linked_input_;
+  return cached_values_.value(time);
 }
 
-void NodeOutput::set_linked_input(NodeInput *link)
+void NodeOutput::cache_value(const TimeRange &time, const QVariant &value)
 {
-  linked_input_ = link;
+  cached_values_.insert(time, value);
+}
+
+void NodeOutput::drop_cached_values()
+{
+  cached_values_.clear();
 }