Add QJoint frontend type

Represents a joint within a skeleton. For now we limit the scale to
a uniform scale represented by a single float. If there is demand
we can extend this to support non-uniform scales for joints using a
QVector3D.

Change-Id: Ib65e45d14c5e40227801c0a70ac5b68557c7e8e9
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

4 files changed, 439 insertions, 4 deletions

diff --git a/src/core/transforms/qjoint.cpp b/src/core/transforms/qjoint.cpp
new file mode 100644
index 000000000..0601ac02f
--- /dev/null
+++ b/src/core/transforms/qjoint.cpp
@@ -0,0 +1,252 @@
+/****************************************************************************
+**
+** 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 "qjoint.h"
+#include "qjoint_p.h"
+
+#include <Qt3DCore/qnodecreatedchange.h>
+#include <Qt3DCore/qpropertynodeaddedchange.h>
+#include <Qt3DCore/qpropertynoderemovedchange.h>
+#include <Qt3DCore/qpropertyupdatedchange.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3DCore {
+
+QJointPrivate::QJointPrivate()
+    : QNodePrivate()
+    , m_rotation()
+    , m_translation()
+    , m_scale(1.0f)
+{
+}
+
+/*!
+    \qmltype Joint
+    \inqmlmodule Qt3D.Core
+    \inherits Node
+    \instantiates Qt3DCore::QJoint
+    \since 5.10
+    \brief Used to transforms parts of skinned meshes
+
+    The Joint node is used to build skeletons as part of the skinned mesh
+    support in Qt 3D. A joint can be transformed by way of its scale, rotation
+    and translation properties. Any mesh vertices that are bound to the joint
+    will have their transformations updated accordingly.
+*/
+
+/*!
+    \qmlproperty real Joint::scale
+
+    Holds the uniform scale of the joint.
+*/
+
+/*!
+    \qmlproperty quaternion Joint::rotation
+
+    Holds the rotation of the joint as quaternion.
+*/
+
+/*!
+    \qmlproperty vector3d Joint::translation
+
+    Holds the translation of the joint as vector3d.
+*/
+
+/*!
+    \class Qt3DCore::QJoint
+    \inmodule Qt3DCore
+    \inherits Qt3DCore::QNode
+    \since 5.10
+    \brief Used to transforms parts of skinned meshes
+
+    The QJoint node is used to build skeletons as part of the skinned mesh
+    support in Qt 3D. A joint can be transformed by way of its scale, rotation
+    and translation properties. Any mesh vertices that are bound to the joint
+    will have their transformations updated accordingly.
+*/
+
+/*!
+    Constructs a new QJoint with \a parent.
+*/
+QJoint::QJoint(Qt3DCore::QNode *parent)
+    : QNode(*new QJointPrivate, parent)
+{
+}
+
+/*! \internal */
+QJoint::~QJoint()
+{
+}
+
+/*!
+    \property Qt3DCore::QJoint::scale
+
+    Holds the uniform scale of the joint.
+*/
+float QJoint::scale() const
+{
+    Q_D(const QJoint);
+    return d->m_scale;
+}
+
+/*!
+    \property Qt3DCore::QJoint::rotation
+
+    Holds the rotation of the joint as QQuaternion.
+*/
+QQuaternion QJoint::rotation() const
+{
+    Q_D(const QJoint);
+    return d->m_rotation;
+}
+
+/*!
+    \property Qt3DCore::QJoint::translation
+
+    Holds the translation of the joint as QVector3D.
+*/
+QVector3D QJoint::translation() const
+{
+    Q_D(const QJoint);
+    return d->m_translation;
+}
+
+void QJoint::setScale(float scale)
+{
+    Q_D(QJoint);
+    if (scale == d->m_scale)
+        return;
+
+    d->m_scale = scale;
+    emit scaleChanged(scale);
+}
+
+void QJoint::setRotation(const QQuaternion &rotation)
+{
+    Q_D(QJoint);
+    if (rotation == d->m_rotation)
+        return;
+
+    d->m_rotation = rotation;
+    emit rotationChanged(rotation);
+}
+
+void QJoint::setTranslation(const QVector3D &translation)
+{
+    Q_D(QJoint);
+    if (translation == d->m_translation)
+        return;
+
+    d->m_translation = translation;
+    emit translationChanged(translation);
+}
+
+/*!
+    Adds \a joint as a child of this joint. If \a joint has no parent, then
+    this joint takes ownership of it. Child joints are in the coordinate system
+    of their parent joint.
+*/
+void QJoint::addChildJoint(QJoint *joint)
+{
+    Q_D(QJoint);
+    if (!d->m_childJoints.contains(joint)) {
+        d->m_childJoints.push_back(joint);
+        // Force creation in backend by setting parent
+        if (!joint->parent())
+            joint->setParent(this);
+
+        // Ensures proper bookkeeping
+        d->registerDestructionHelper(joint, &QJoint::removeChildJoint, d->m_childJoints);
+
+        if (d->m_changeArbiter != nullptr) {
+            const auto change = QPropertyNodeAddedChangePtr::create(id(), joint);
+            change->setPropertyName("childJoint");
+            d->notifyObservers(change);
+        }
+    }
+}
+
+/*!
+    Removes \a joint from this joint's list of children. The child joint is not
+    destroyed.
+*/
+void QJoint::removeChildJoint(QJoint *joint)
+{
+    Q_D(QJoint);
+    if (d->m_childJoints.contains(joint)) {
+
+        if (d->m_changeArbiter != nullptr) {
+            const auto change = QPropertyNodeRemovedChangePtr::create(id(), joint);
+            change->setPropertyName("childJoint");
+            d->notifyObservers(change);
+        }
+
+        d->m_childJoints.removeOne(joint);
+
+        // Remove bookkeeping connection
+        d->unregisterDestructionHelper(joint);
+    }
+}
+
+/*!
+    The vector of joints this joint has as children.
+*/
+QVector<QJoint *> QJoint::childJoints() const
+{
+    Q_D(const QJoint);
+    return d->m_childJoints;
+}
+
+/*! \internal */
+Qt3DCore::QNodeCreatedChangeBasePtr QJoint::createNodeCreationChange() const
+{
+    auto creationChange = Qt3DCore::QNodeCreatedChangePtr<QJointData>::create(this);
+    auto &data = creationChange->data;
+    Q_D(const QJoint);
+    data.childJointIds = qIdsForNodes(d->m_childJoints);
+    data.rotation = d->m_rotation;
+    data.scale = d->m_scale;
+    data.translation = d->m_translation;
+    return creationChange;
+}
+
+} // namespace Qt3DCore
+
+QT_END_NAMESPACE
diff --git a/src/core/transforms/qjoint.h b/src/core/transforms/qjoint.h
new file mode 100644
index 000000000..913716380
--- /dev/null
+++ b/src/core/transforms/qjoint.h
@@ -0,0 +1,93 @@
+/****************************************************************************
+**
+** 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.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QT3DCORE_QJOINT_H
+#define QT3DCORE_QJOINT_H
+
+#include <Qt3DCore/qnode.h>
+#include <Qt3DCore/qt3dcore_global.h>
+
+#include <QtGui/qquaternion.h>
+#include <QtGui/qvector3d.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3DCore {
+
+class QJointPrivate;
+
+class QT3DCORESHARED_EXPORT QJoint : public QNode
+{
+    Q_OBJECT
+    Q_PROPERTY(float scale READ scale WRITE setScale NOTIFY scaleChanged)
+    Q_PROPERTY(QQuaternion rotation READ rotation WRITE setRotation NOTIFY rotationChanged)
+    Q_PROPERTY(QVector3D translation READ translation WRITE setTranslation NOTIFY translationChanged)
+
+public:
+    explicit QJoint(Qt3DCore::QNode *parent = nullptr);
+    ~QJoint();
+
+    float scale() const;
+    QQuaternion rotation() const;
+    QVector3D translation() const;
+
+    void addChildJoint(QJoint *joint);
+    void removeChildJoint(QJoint *joint);
+    QVector<QJoint *> childJoints() const;
+
+public Q_SLOTS:
+    void setScale(float scale);
+    void setRotation(const QQuaternion &rotation);
+    void setTranslation(const QVector3D &translation);
+
+Q_SIGNALS:
+    void scaleChanged(float scale);
+    void rotationChanged(const QQuaternion &rotation);
+    void translationChanged(const QVector3D &translation);
+
+private:
+    Q_DECLARE_PRIVATE(QJoint)
+    Qt3DCore::QNodeCreatedChangeBasePtr createNodeCreationChange() const override;
+};
+
+} // namespace Qt3DCore
+
+QT_END_NAMESPACE
+
+#endif // QT3DCORE_QJOINT_H
diff --git a/src/core/transforms/qjoint_p.h b/src/core/transforms/qjoint_p.h
new file mode 100644
index 000000000..021824b28
--- /dev/null
+++ b/src/core/transforms/qjoint_p.h
@@ -0,0 +1,87 @@
+/****************************************************************************
+**
+** 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.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QT3DCORE_QJOINT_P_H
+#define QT3DCORE_QJOINT_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of other Qt classes.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <Qt3DCore/private/qnode_p.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3DCore {
+
+class QJoint;
+
+class QJointPrivate : public QNodePrivate
+{
+public:
+    QJointPrivate();
+
+    Q_DECLARE_PUBLIC(QJoint)
+
+    QVector<QJoint *> m_childJoints;
+    QQuaternion m_rotation;
+    QVector3D m_translation;
+    float m_scale;
+};
+
+struct QJointData
+{
+    QNodeIdVector childJointIds;
+    QQuaternion rotation;
+    QVector3D translation;
+    float scale;
+};
+
+} // namespace Qt3DCore
+
+QT_END_NAMESPACE
+
+#endif // QT3DCORE_QJOINT_P_H
diff --git a/src/core/transforms/transforms.pri b/src/core/transforms/transforms.pri
index 75ae7c7a9..aa214c693 100644
--- a/src/core/transforms/transforms.pri
+++ b/src/core/transforms/transforms.pri
@@ -1,10 +1,13 @@
 
 SOURCES += \
-        $$PWD/qtransform.cpp
+    $$PWD/qtransform.cpp \
+    $$PWD/qjoint.cpp
 
 HEADERS += \
-        $$PWD/qtransform.h \
-        $$PWD/qtransform_p.h \
-        $$PWD/qmath3d_p.h
+    $$PWD/qtransform.h \
+    $$PWD/qtransform_p.h \
+    $$PWD/qmath3d_p.h \
+    $$PWD/qjoint.h \
+    $$PWD/qjoint_p.h
 
 INCLUDEPATH += $$PWD