Add QArmature component

This will be used by the renderer to perform skinning of the mesh
passed to QGeometryRenderer when coupled with a suitable vertex
shader via QMaterial.

Change-Id: I54f414313ba04aea5f2f1777244cb93cd1bfd688
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

1 files changed, 172 insertions, 0 deletions

diff --git a/src/core/transforms/qarmature.cpp b/src/core/transforms/qarmature.cpp
new file mode 100644
index 000000000..65a13b262
--- /dev/null
+++ b/src/core/transforms/qarmature.cpp
@@ -0,0 +1,172 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 Klaralvdalens Datakonsult AB (KDAB).
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt3D module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qarmature.h"
+#include "qarmature_p.h"
+#include <Qt3DCore/qabstractskeleton.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3DCore {
+
+QArmaturePrivate::QArmaturePrivate()
+    : Qt3DCore::QComponentPrivate()
+    , m_skeleton(nullptr)
+{
+}
+
+/*!
+    \qmltype Armature
+    \inqmlmodule Qt3D.Core
+    \inherits Component3D
+    \instantiates Qt3DCore::QArmature
+    \since 5.10
+    \brief Used to calculate skinning transform matrices and set them on shaders
+
+    The Armature component is aggregated by entities to give them the ability to
+    calculate the palette of skinning transform matrices needed to properly
+    render skinned meshes.
+
+    Each vertex in a skinned mesh is associated (bound) to up to 4 joints in a
+    skeleton. For each joint affecting a vertex the mesh also provides a weight
+    which determines the level of influence of the corresponding joint. The
+    skinning palette used for performing the transformation of skinned vertices
+    is provided by the Armature and is calculated from the joints contained in
+    the referenced skeleton.
+
+    Updating the local transform of a joint results in the skinning matrices
+    being recalculated and the skinned mesh vertices bound to that joint moving
+    accordingly.
+*/
+
+/*!
+    \qmlproperty AbstractSkeleton Armature::skeleton
+
+    Holds the skeleton used to calculate the skinning transform matrix palette.
+*/
+
+/*!
+    \class Qt3DCore::QArmature
+    \inmodule Qt3DCore
+    \inherits Qt3DCore::QComponent
+    \since 5.10
+    \brief Used to calculate skinning transform matrices and set them on shaders
+
+    The Armature component is aggregated by entities to give them the ability to
+    calculate the palette of skinning transform matrices needed to properly
+    render skinned meshes.
+
+    Each vertex in a skinned mesh is associated (bound) to up to 4 joints in a
+    skeleton. For each joint affecting a vertex the mesh also provides a weight
+    which determines the level of influence of the corresponding joint. The
+    skinning palette used for performing the transformation of skinned vertices
+    is provided by the Armature and is calculated from the joints contained in
+    the referenced skeleton.
+
+    Updating the local transform of a joint results in the skinning matrices
+    being recalculated and the skinned mesh vertices bound to that joint moving
+    accordingly.
+*/
+
+/*!
+    Constructs a new QArmature with \a parent.
+*/
+QArmature::QArmature(Qt3DCore::QNode *parent)
+    : Qt3DCore::QComponent(*new QArmaturePrivate, parent)
+{
+}
+
+/*! \internal */
+QArmature::QArmature(QArmaturePrivate &dd, Qt3DCore::QNode *parent)
+    : Qt3DCore::QComponent(dd, parent)
+{
+}
+
+/*! \internal */
+QArmature::~QArmature()
+{
+}
+
+/*!
+    \property Qt3DCore::QArmature::skeleton
+
+    Holds the skeleton used to calculate the skinning transform matrix palette.
+*/
+Qt3DCore::QAbstractSkeleton *QArmature::skeleton() const
+{
+    Q_D(const QArmature);
+    return d->m_skeleton;
+}
+
+void QArmature::setSkeleton(Qt3DCore::QAbstractSkeleton *skeleton)
+{
+    Q_D(QArmature);
+    if (d->m_skeleton != skeleton) {
+        if (d->m_skeleton)
+            d->unregisterDestructionHelper(d->m_skeleton);
+
+        // We need to add it as a child of the current node if it has been declared inline
+        // Or not previously added as a child of the current node so that
+        // 1) The backend gets notified about it's creation
+        // 2) When the current node is destroyed, it gets destroyed as well
+        if (skeleton && !skeleton->parent())
+            skeleton->setParent(this);
+        d->m_skeleton = skeleton;
+
+        // Ensures proper bookkeeping
+        if (d->m_skeleton)
+            d->registerDestructionHelper(d->m_skeleton, &QArmature::setSkeleton, d->m_skeleton);
+
+        emit skeletonChanged(skeleton);
+    }
+}
+
+/*! \internal */
+Qt3DCore::QNodeCreatedChangeBasePtr QArmature::createNodeCreationChange() const
+{
+    auto creationChange = Qt3DCore::QNodeCreatedChangePtr<QArmatureData>::create(this);
+    auto &data = creationChange->data;
+    Q_D(const QArmature);
+    data.skeletonId = qIdForNode(d->m_skeleton);
+    return creationChange;
+}
+
+} // namespace Qt3DCore
+
+QT_END_NAMESPACE