Add virtual doBlend to ClipBlendNode and subclasses

This is called by the non virtual performBlend (will be renamed
once old implementation is removed). The key here is that all
nodes in the blend tree will have the exact same layout for the
ClipResults for a given animator. This means we don't need to have
a mapping data structure for every node in the tree. This really
simplifies the blending implementation and will allow us to
parallelise this much better in the future as each blend node
could make use of a parallel_for() or map() type operation.

To achieve this we will need to perform a gather operation that
maps the ClipResults coming straight out of an animation clip
to the ClipResults layout used by the blend tree as described
above. This will be done in a follow up commit.

Change-Id: I389383d3b9197a6ef36b529f44ac89cb5c593023
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/src/animation/backend/clipblendnode.cpp b/src/animation/backend/clipblendnode.cpp
index 18d57b0c7..f22df7b74 100644
--- a/src/animation/backend/clipblendnode.cpp
+++ b/src/animation/backend/clipblendnode.cpp
@@ -200,6 +200,34 @@ ClipResults ClipBlendNode::clipResults(Qt3DCore::QNodeId animatorId) const
     evaluated in one pass, and the tree in a subsequent pass.
 */
 
+/*!
+    \internal
+
+    Fetches the ClipResults from the nodes listed in the dependencyIds
+    and passes them to the doBlend() virtual function which should be
+    implemented in subclasses to perform the actual blend operation.
+    The results are then inserted into the clip results for this blend
+    node indexed by the \a animatorId.
+*/
+void ClipBlendNode::performBlend(Qt3DCore::QNodeId animatorId)
+{
+    // Obtain the clip results from each of the dependencies
+    const QVector<Qt3DCore::QNodeId> dependencyNodeIds = dependencyIds();
+    const int dependencyCount = dependencyNodeIds.size();
+    QVector<ClipResults> blendData;
+    blendData.reserve(dependencyCount);
+    for (const auto dependencyId : dependencyNodeIds) {
+        ClipBlendNode *dependencyNode = clipBlendNodeManager()->lookupNode(dependencyId);
+        ClipResults blendDataElement = dependencyNode->clipResults(animatorId);
+        blendData.push_back(blendDataElement);
+    }
+
+    // Ask the blend node to perform the actual blend operation on the data
+    // from the dependencies
+    ClipResults blendedResults = doBlend(blendData);
+    setClipResults(animatorId, blendedResults);
+}
+
 } // Animation
 
 } // Qt3DAnimation