Add a function to calculate the default value for missing channels

Change-Id: Ic7bee59324da81fe2e467fd940029706297fc286
Reviewed-by: Christian Stromme <christian.stromme@qt.io>
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

2 files changed, 72 insertions, 0 deletions

diff --git a/src/animation/backend/animationutils.cpp b/src/animation/backend/animationutils.cpp
index 3096a2647..8652c7df1 100644
--- a/src/animation/backend/animationutils.cpp
+++ b/src/animation/backend/animationutils.cpp
@@ -88,6 +88,16 @@ int componentsForType(int type)
     return componentCount;
 }
 
+inline QVector<float> valueToVector(const QVector3D &value)
+{
+    return { value.x(), value.y(), value.z() };
+}
+
+inline QVector<float> valueToVector(const QQuaternion &value)
+{
+    return { value.scalar(), value.x(), value.y(), value.z() };
+}
+
 ClipEvaluationData evaluationDataForClip(AnimationClip *clip,
                                          const AnimatorEvaluationData &animatorData)
 {
@@ -779,6 +789,65 @@ ClipResults evaluateBlendTree(Handler *handler,
     return blendTreeRootNode->clipResults(animatorId);
 }
 
+QVector<float> defaultValueForChannel(Handler *handler,
+                                      const ChannelNameAndType &channelDescription)
+{
+    QVector<float> result;
+
+    // Does the channel repesent a joint in a skeleton or is it a general channel?
+    ChannelMappingManager *mappingManager = handler->channelMappingManager();
+    const ChannelMapping *mapping = mappingManager->lookupResource(channelDescription.mappingId);
+    switch (mapping->mappingType()) {
+    case ChannelMapping::SkeletonMappingType: {
+        // Default channel values for a joint in a skeleton, should be taken
+        // from the default pose of the joint itself. I.e. if a joint is not
+        // explicitly animated, then it should retain it's initial rest pose.
+        Skeleton *skeleton = mapping->skeleton();
+        const int jointIndex = channelDescription.jointIndex;
+        switch (channelDescription.jointTransformComponent) {
+        case Translation:
+            result = valueToVector(skeleton->jointTranslation(jointIndex));
+            break;
+
+        case Rotation:
+            result = valueToVector(skeleton->jointRotation(jointIndex));
+            break;
+
+        case Scale:
+            result = valueToVector(skeleton->jointScale(jointIndex));
+            break;
+
+        case NoTransformComponent:
+            Q_UNREACHABLE();
+            break;
+        }
+        break;
+    }
+
+    case ChannelMapping::ChannelMappingType:
+    case ChannelMapping::CallbackMappingType: {
+        // Do our best to provide a sensible default value.
+        if (channelDescription.type == QMetaType::QQuaternion) {
+            result = valueToVector(QQuaternion()); // (1, 0, 0, 0)
+            break;
+        }
+
+        if (channelDescription.name.toLower() == QLatin1String("scale")) {
+            result = valueToVector(QVector3D(1.0f, 1.0f, 1.0f));
+            break;
+        }
+
+        // Everything else gets all zeros
+        const int componentCount = componentsForType(channelDescription.type);
+        result = QVector<float>(componentCount, 0.0f);
+        break;
+    }
+
+    }
+
+    return result;
+}
+
 } // Animation
 } // Qt3DAnimation
 
diff --git a/src/animation/backend/animationutils_p.h b/src/animation/backend/animationutils_p.h
index 915a91bca..6a1b18936 100644
--- a/src/animation/backend/animationutils_p.h
+++ b/src/animation/backend/animationutils_p.h
@@ -335,6 +335,9 @@ ClipResults evaluateBlendTree(Handler *handler,
                               BlendedClipAnimator *animator,
                               Qt3DCore::QNodeId blendNodeId);
 
+Q_AUTOTEST_EXPORT
+QVector<float> defaultValueForChannel(Handler *handler, const ChannelNameAndType &channelDescription);
+
 } // Animation
 } // Qt3DAnimation