Add function to format clip results using a gather operation

If an index in the format is -1 put a default value of 0 into the
formatted results. This will allow clips to not have to provide every
channel used anywhere by the blend tree.

Change-Id: I9e18d0840e75a959ef680cbd54259a74c9331fa8
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

2 files changed, 22 insertions, 0 deletions

diff --git a/src/animation/backend/animationutils.cpp b/src/animation/backend/animationutils.cpp
index 8f1a681d4..8b2ba6821 100644
--- a/src/animation/backend/animationutils.cpp
+++ b/src/animation/backend/animationutils.cpp
@@ -369,6 +369,24 @@ QVector<Qt3DCore::QNodeId> gatherValueNodesToEvaluate(Handler *handler,
     return clipIds;
 }
 
+ClipResults formatClipResults(const ClipResults &rawClipResults,
+                              const ComponentIndices &format)
+{
+    // Resize the output to match the number of indices
+    const int elementCount = format.size();
+    ClipResults formattedClipResults(elementCount);
+
+    // Perform a gather operation to format the data
+    // TODO: For large numbers of components do this in parallel with
+    // for e.g. a parallel_for() like construct
+    for (int i = 0; i < elementCount; ++i) {
+        const float value = format[i] != -1 ? rawClipResults[format[i]] : 0.0f;
+        formattedClipResults[i] = value;
+    }
+
+    return formattedClipResults;
+}
+
 ClipResults evaluateBlendTree(Handler *handler,
                               BlendedClipAnimator *animator,
                               Qt3DCore::QNodeId blendTreeRootId)
diff --git a/src/animation/backend/animationutils_p.h b/src/animation/backend/animationutils_p.h
index da85451f8..705e37c34 100644
--- a/src/animation/backend/animationutils_p.h
+++ b/src/animation/backend/animationutils_p.h
@@ -173,6 +173,10 @@ QVector<Qt3DCore::QNodeId> gatherValueNodesToEvaluate(Handler *handler,
                                                       Qt3DCore::QNodeId blendTreeRootId);
 
 Q_AUTOTEST_EXPORT
+ClipResults formatClipResults(const ClipResults &rawClipResults,
+                              const ComponentIndices &format);
+
+Q_AUTOTEST_EXPORT
 ClipResults evaluateBlendTree(Handler *handler,
                               BlendedClipAnimator *animator,
                               Qt3DCore::QNodeId blendNodeId);