Add support for loading specific animations from glTF 2 files

Can now specify source urls to QAnimationClipLoader with query
parameters for animationIndex or animationName.

Add a new manual test to demonstrate/test this by loading the 2nd
animation from the Rigged-Simple.gltf file.

Will followup with the same support for Qt 3D native json animation
files.

Change-Id: Icb66073f29b8471fe06e2e2e9c43720567dc9ee5
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

4 files changed, 53 insertions, 12 deletions

diff --git a/src/animation/backend/animationclip.cpp b/src/animation/backend/animationclip.cpp
index e8f8f4552..cc0a91ce0 100644
--- a/src/animation/backend/animationclip.cpp
+++ b/src/animation/backend/animationclip.cpp
@@ -50,9 +50,13 @@
 #include <QtCore/qjsonarray.h>
 #include <QtCore/qjsondocument.h>
 #include <QtCore/qjsonobject.h>
+#include <QtCore/qurlquery.h>
 
 QT_BEGIN_NAMESPACE
 
+#define ANIMATION_INDEX_KEY     QLatin1String("animationIndex")
+#define ANIMATION_NAME_KEY      QLatin1String("animationName")
+
 namespace Qt3DAnimation {
 namespace Animation {
 
@@ -210,15 +214,36 @@ void AnimationClip::loadAnimationFromUrl()
         return;
     }
 
+    // Extract the animationName or animationIndex from the url query parameters.
+    // If both present, animationIndex wins.
+    int animationIndex = -1;
+    QString animationName;
+    if (m_source.hasQuery()) {
+        QUrlQuery query(m_source);
+        if (query.hasQueryItem(ANIMATION_INDEX_KEY)) {
+            bool ok = false;
+            int i = query.queryItemValue(ANIMATION_INDEX_KEY).toInt(&ok);
+            if (ok)
+                animationIndex = i;
+        }
+
+        if (animationIndex == -1 && query.hasQueryItem(ANIMATION_NAME_KEY)) {
+            animationName = query.queryItemValue(ANIMATION_NAME_KEY);
+        }
+
+        qCDebug(Jobs) << "animationIndex =" << animationIndex;
+        qCDebug(Jobs) << "animationName =" << animationName;
+    }
+
     // TODO: Convert to plugins
     // Load glTF or "native"
     if (filePath.endsWith(QLatin1String("gltf"))) {
         qCDebug(Jobs) << "Loading glTF animation from" << filePath;
         GLTFImporter gltf;
         gltf.load(&file);
-        // TODO: Allow loading of a named animation from a file containing many
-        m_name = gltf.animations().first().name;
-        m_channels = gltf.createAnimationData();
+        auto nameAndChannels = gltf.createAnimationData(animationIndex, animationName);
+        m_name = nameAndChannels.name;
+        m_channels = nameAndChannels.channels;
     } else if (filePath.endsWith(QLatin1String("json"))) {
         // Native format
         QByteArray animationData = file.readAll();
diff --git a/src/animation/backend/gltfimporter.cpp b/src/animation/backend/gltfimporter.cpp
index d9c0cb9a6..e91dd5661 100644
--- a/src/animation/backend/gltfimporter.cpp
+++ b/src/animation/backend/gltfimporter.cpp
@@ -466,16 +466,15 @@ QHash<int, int> GLTFImporter::createNodeIndexToJointIndexMap(const Skin &skin) c
     return nodeIndexToJointIndexMap;
 }
 
-QVector<Qt3DAnimation::Animation::Channel> GLTFImporter::createAnimationData(const QString &animationName) const
+GLTFImporter::AnimationNameAndChannels GLTFImporter::createAnimationData(int animationIndex, const QString &animationName) const
 {
-    QVector<Qt3DAnimation::Animation::Channel> channels;
+    AnimationNameAndChannels nameAndChannels;
     if (m_animations.isEmpty()) {
         qCWarning(Jobs) << "File does not contain any animation data";
-        return channels;
+        return nameAndChannels;
     }
 
-    int animationIndex = 0;
-    if (!animationName.isEmpty()) {
+    if (animationIndex == -1 && !animationName.isEmpty()) {
         for (int i = 0; i < m_animations.size(); ++i) {
             if (m_animations[i].name == animationName) {
                 animationIndex = i;
@@ -483,7 +482,13 @@ QVector<Qt3DAnimation::Animation::Channel> GLTFImporter::createAnimationData(con
             }
         }
     }
+
+    if (animationIndex >= m_animations.size()) {
+        qCWarning(Jobs) << "Invalid animation index. Skipping.";
+        return nameAndChannels;
+    }
     const Animation &animation = m_animations[animationIndex];
+    nameAndChannels.name = animation.name;
 
     // Create node index to joint index lookup tables for each skin
     QVector<QHash<int, int>> nodeIndexToJointIndexMaps;
@@ -621,11 +626,11 @@ QVector<Qt3DAnimation::Animation::Channel> GLTFImporter::createAnimationData(con
         } // case 4
         }
 
-        channels.push_back(outputChannel);
+        nameAndChannels.channels.push_back(outputChannel);
         ++channelIndex;
     }
 
-    return channels;
+    return nameAndChannels;
 }
 
 GLTFImporter::RawData GLTFImporter::accessorData(int accessorIndex, int index) const
diff --git a/src/animation/backend/gltfimporter_p.h b/src/animation/backend/gltfimporter_p.h
index ae7674fe7..e31f8d078 100644
--- a/src/animation/backend/gltfimporter_p.h
+++ b/src/animation/backend/gltfimporter_p.h
@@ -182,7 +182,12 @@ public:
     bool load(QIODevice *ioDev);
     const QVector<Animation> animations() const { return m_animations; }
 
-    QVector<Qt3DAnimation::Animation::Channel> createAnimationData(const QString &animationName = QString()) const;
+    struct AnimationNameAndChannels
+    {
+        QString name;
+        QVector<Qt3DAnimation::Animation::Channel> channels;
+    };
+    AnimationNameAndChannels createAnimationData(int animationIndex, const QString &animationName = QString()) const;
 
 private:
     static Qt3DRender::QAttribute::VertexBaseType accessorTypeFromJSON(int componentType);
diff --git a/src/animation/frontend/qanimationcliploader.cpp b/src/animation/frontend/qanimationcliploader.cpp
index be23f49a3..423ca136c 100644
--- a/src/animation/frontend/qanimationcliploader.cpp
+++ b/src/animation/frontend/qanimationcliploader.cpp
@@ -77,7 +77,13 @@ void QAnimationClipLoaderPrivate::setStatus(QAnimationClipLoader::Status status)
 /*!
     \property Qt3DAnimation::QAnimationClipLoader::source
 
-    Holds the source URL from which to load the animation clip.
+    Holds the source URL from which to load the animation clip. Currently
+    glTF2 and the native Qt 3D json animation file formats are supported.
+
+    In the case where a file contains multiple animations, it is possible
+    to select which animation should be loaded by way of query parameters
+    on the source url. The accepted query parameters are animationIndex and
+    animationName. If both are specified, animationName is ignored.
 */
 /*!
     \class Qt3DAnimation::QAnimationClipLoader