Add methods to set and retrieve format indices for a blend value node

In order to have a consistent data layout for all interior nodes of a
blend tree, we need a place to convert from whatever data layout a
clip produces when evaluated to the format used  by the blend tree. We
will do this by creating for each value leaf node a vector of indices
that can be used to map from the ClipResults layout output by the clip
to the ClipResults format used by the blend tree.

With this approach, we can do the following:

* Evaluate each leaf node in the blend tree
* Perform a gather operation using these format indices to reorder the
  data into a consistent layout for the whole blend tree
* Evaluate the blend tree using this consistent layout

This completely avoids having to perform complex mappings when
evaluating each blend node, which is a significant saving in
overhead and allows for more parallellism in the future.

Change-Id: Ie534534f9555842d0d0f1a89fc996e25f5c6ce9e
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>
Reviewed-by: Mike Krus <mike.krus@kdab.com>

2 files changed, 27 insertions, 0 deletions

diff --git a/src/animation/backend/clipblendvalue.cpp b/src/animation/backend/clipblendvalue.cpp
index a1726a40a..d3970c24b 100644
--- a/src/animation/backend/clipblendvalue.cpp
+++ b/src/animation/backend/clipblendvalue.cpp
@@ -98,6 +98,27 @@ double ClipBlendValue::duration() const
     return clip->duration();
 }
 
+void ClipBlendValue::setFormatIndices(Qt3DCore::QNodeId animatorId, const ComponentIndices &formatIndices)
+{
+    // Do we already have an entry for this animator?
+    const int animatorIndex = m_animatorIds.indexOf(animatorId);
+    if (animatorIndex == -1) {
+        // Nope, add it
+        m_animatorIds.push_back(animatorId);
+        m_formatIndicies.push_back(formatIndices);
+    } else {
+        m_formatIndicies[animatorIndex] = formatIndices;
+    }
+}
+
+ComponentIndices ClipBlendValue::formatIndices(Qt3DCore::QNodeId animatorId)
+{
+    const int animatorIndex = m_animatorIds.indexOf(animatorId);
+    if (animatorIndex != -1)
+        return m_formatIndicies[animatorIndex];
+    return ComponentIndices();
+}
+
 } // namespace Animation
 } // namespace Qt3DAnimation
 
diff --git a/src/animation/backend/clipblendvalue_p.h b/src/animation/backend/clipblendvalue_p.h
index f06800488..21cc4adf3 100644
--- a/src/animation/backend/clipblendvalue_p.h
+++ b/src/animation/backend/clipblendvalue_p.h
@@ -74,6 +74,9 @@ public:
 
     double duration() const Q_DECL_OVERRIDE;
 
+    void setFormatIndices(Qt3DCore::QNodeId animatorId, const ComponentIndices &formatIndices);
+    ComponentIndices formatIndices(Qt3DCore::QNodeId animatorId);
+
 protected:
     ClipResults doBlend(const QVector<ClipResults> &blendData) const Q_DECL_OVERRIDE;
 
@@ -81,6 +84,9 @@ private:
     void initializeFromPeer(const Qt3DCore::QNodeCreatedChangeBasePtr &change) Q_DECL_FINAL;
 
     Qt3DCore::QNodeId m_clipId;
+
+    QVector<Qt3DCore::QNodeId> m_animatorIds;
+    QVector<ComponentIndices> m_formatIndicies;
 };
 
 } // namespace Animation