Fix Entity parenting hierarchy

When the initial Entity backend node hierarchy is created it skips over
any non-entity nodes to ensure that Entities are only parented to
other Entities. Calling QNode::setParent breaks this when reparenting
Entities to non-entity nodes.

Fix by sending a new "parentEntityUpdated" property update that backend
Entity nodes listen for. They keep the id of their new parent and flag
the need to rebuild the entity hierarchy.  This triggers a new job to
clear the children and parents of every backend Entity, then rebuilds
the hierarchy using the stored parent ID in each Entity. This is much
more forgiving of creation/parenting ordering issues and shouldn't be
less performant because any Entity reparent was previously marking
everything dirty anyway.

Add a new test from QTBUG-73905 that creates 4 cylinders and manipulates
the parents in different ways.

Add a new test to tst_nodes to reparent a QEntity to a QNode and ensure
the entity finds it's correct QEntity parent.

Add a new test to tst_entity to ensure backend nodes correctly handle
the new parenting events.

Task-number: QTBUG-73905
Change-Id: Iab0203947d89bbed2868b3629fbde879675fe568
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

2 files changed, 252 insertions, 0 deletions

diff --git a/tests/manual/cylinder-parent-test/cylinder-parent-test.pro b/tests/manual/cylinder-parent-test/cylinder-parent-test.pro
new file mode 100644
index 000000000..d3db3bc76
--- /dev/null
+++ b/tests/manual/cylinder-parent-test/cylinder-parent-test.pro
@@ -0,0 +1,9 @@
+!include( ../manual.pri ) {
+    error( "Couldn't find the manual.pri file!" )
+}
+
+QT += 3dcore 3drender 3dinput 3dextras
+
+SOURCES += main.cpp
+
+
diff --git a/tests/manual/cylinder-parent-test/main.cpp b/tests/manual/cylinder-parent-test/main.cpp
new file mode 100644
index 000000000..823461a28
--- /dev/null
+++ b/tests/manual/cylinder-parent-test/main.cpp
@@ -0,0 +1,243 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 Klaralvdalens Datakonsult AB (KDAB).
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt3D module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** 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 General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** 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-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QGuiApplication>
+#include <QTimer>
+
+#include <Qt3DInput/QInputAspect>
+
+#include <Qt3DRender/qcamera.h>
+#include <Qt3DRender/qcameralens.h>
+#include <Qt3DExtras/qcylindermesh.h>
+#include <Qt3DRender/qmesh.h>
+#include <Qt3DRender/qtechnique.h>
+#include <Qt3DExtras/qphongmaterial.h>
+#include <Qt3DRender/qeffect.h>
+#include <Qt3DRender/qtexture.h>
+#include <Qt3DRender/qrenderpass.h>
+#include <Qt3DRender/qrenderaspect.h>
+#include <Qt3DExtras/qforwardrenderer.h>
+
+#include <Qt3DCore/qentity.h>
+#include <Qt3DCore/qtransform.h>
+#include <Qt3DCore/qaspectengine.h>
+
+#include <Qt3DExtras/qt3dwindow.h>
+#include <Qt3DExtras/qorbitcameracontroller.h>
+#include <QThread>
+#include <QLoggingCategory>
+
+#include <type_traits>
+
+int main(int argc, char **argv)
+{
+    QGuiApplication app(argc, argv);
+    Qt3DExtras::Qt3DWindow view;
+
+    QLoggingCategory::setFilterRules("Qt3D.Renderer.RenderNodes=true");
+
+    // Root entity
+    Qt3DCore::QEntity *rootEntity = new Qt3DCore::QEntity();
+    view.setRootEntity(rootEntity);
+    rootEntity->setObjectName("Root Entity");
+
+    // Set root object of the scene
+    view.show();
+
+    // Camera
+    Qt3DRender::QCamera *camera = view.camera();
+    camera->lens()->setPerspectiveProjection(45.0f, 16.0f / 9.0f, 0.1f, 1000.0f);
+    camera->setPosition(QVector3D(0, 0, 20.0f));
+    camera->setUpVector(QVector3D(0, 1, 0));
+    camera->setViewCenter(QVector3D(0, 0, 0));
+
+    // For camera controls
+    Qt3DExtras::QOrbitCameraController *cameraController = new Qt3DExtras::QOrbitCameraController(rootEntity);
+    cameraController->setCamera(camera);
+
+    // Cylinder shape data
+    Qt3DExtras::QCylinderMesh *mesh = new Qt3DExtras::QCylinderMesh();
+
+    qDebug() << "Setup complete.  Creating cylinders\n";
+
+    // simple setParent from nullptr (OK for QTBUG-73905)
+    // green cylinder, bottom left
+    {
+        Qt3DCore::QTransform *leftTransform = new Qt3DCore::QTransform;
+        leftTransform->setTranslation(QVector3D(-5, -2, 0));
+        leftTransform->setObjectName("Green transform");
+
+        Qt3DExtras::QPhongMaterial *greenMaterial = new Qt3DExtras::QPhongMaterial(rootEntity);
+        greenMaterial->setObjectName("Green Material");
+        greenMaterial->setDiffuse(Qt::green);
+
+        Qt3DCore::QEntity *grandParentNode = new Qt3DCore::QEntity();
+        Qt3DCore::QEntity *parentNode = new Qt3DCore::QEntity();
+        Qt3DCore::QEntity *leafNode = new Qt3DCore::QEntity();
+        grandParentNode->setObjectName("Green Grandparent");
+        parentNode->setObjectName("Green Parent");
+        leafNode->setObjectName("Green Leaf");
+
+        leafNode->addComponent(mesh);
+        leafNode->addComponent(greenMaterial);
+        parentNode->addComponent(leftTransform);
+
+        grandParentNode->setParent(rootEntity);
+        parentNode->setParent(grandParentNode);
+        leafNode->setParent(parentNode);
+    }
+
+    // simple setParent from rootEntity (doesn't work QTBUG-73905)
+    // yellow cylinder, top left
+    {
+        Qt3DCore::QTransform *leftTransform = new Qt3DCore::QTransform;
+        leftTransform->setTranslation(QVector3D(-5, 2, 0));
+        leftTransform->setObjectName("Yellow Transform");
+
+        Qt3DExtras::QPhongMaterial *yellowMaterial = new Qt3DExtras::QPhongMaterial(rootEntity);
+        yellowMaterial->setObjectName("Yellow Material");
+        yellowMaterial->setDiffuse(Qt::yellow);
+
+        Qt3DCore::QEntity *grandParentNode = new Qt3DCore::QEntity(rootEntity);
+        Qt3DCore::QEntity *parentNode = new Qt3DCore::QEntity(rootEntity);
+        Qt3DCore::QEntity *leafNode = new Qt3DCore::QEntity(rootEntity);
+        leafNode->setObjectName("Yellow Leaf");
+        grandParentNode->setObjectName("Yellow Grandparent");
+        parentNode->setObjectName("Yellow Parent");
+
+        leafNode->addComponent(mesh);
+        leafNode->addComponent(yellowMaterial);
+        parentNode->addComponent(leftTransform);
+
+        // sometimes this can change things
+        //QCoreApplication::processEvents();
+
+        grandParentNode->setParent(rootEntity);
+        parentNode->setParent(grandParentNode);
+        leafNode->setParent(parentNode);
+    }
+
+    // complex setParent from nullptr (OK QTBUG-73905?)
+    // red cylinder, Bottom-right
+    {
+        Qt3DCore::QNode *tree1node1 = new Qt3DCore::QNode();
+        Qt3DCore::QEntity *tree1node2 = new Qt3DCore::QEntity();
+        Qt3DCore::QNode *tree1node3 = new Qt3DCore::QNode();
+        tree1node1->setObjectName("Red Tree1-Node1");
+        tree1node2->setObjectName("Red Tree1-Node2");
+        tree1node3->setObjectName("Red Tree1-Node3");
+
+        Qt3DCore::QNode *tree2node1 = new Qt3DCore::QNode();
+        Qt3DCore::QEntity *tree2node2 = new Qt3DCore::QEntity();
+        Qt3DCore::QNode *tree2node3 = new Qt3DCore::QNode();
+        tree2node1->setObjectName("Red Tree2-Node1");
+        tree2node2->setObjectName("Red Tree2-Node2");
+        tree2node3->setObjectName("Red Tree2-Node3");
+
+        Qt3DCore::QTransform *wrongRedTransform = new Qt3DCore::QTransform;
+        wrongRedTransform->setTranslation(QVector3D(1, -1, 0));
+        Qt3DCore::QTransform *bottomRightTransform = new Qt3DCore::QTransform;
+        bottomRightTransform->setTranslation(QVector3D(5, -2, 0));
+        bottomRightTransform->setObjectName("Red BR Transform");
+        wrongRedTransform->setObjectName("Red Wrong Transform");
+
+        Qt3DExtras::QPhongMaterial *redMaterial = new Qt3DExtras::QPhongMaterial(rootEntity);
+        redMaterial->setDiffuse(Qt::red);
+        redMaterial->setObjectName("Red Material");
+        Qt3DCore::QEntity *leafNode = new Qt3DCore::QEntity();
+        leafNode->setObjectName("Red Leaf");
+        leafNode->addComponent(mesh);
+        leafNode->addComponent(redMaterial);
+
+        tree1node2->addComponent(wrongRedTransform);
+        tree2node2->addComponent(bottomRightTransform);
+
+        tree1node1->setParent(rootEntity);
+        tree1node2->setParent(tree1node1);
+        tree1node3->setParent(tree1node2);
+
+        tree2node1->setParent(rootEntity);
+        tree2node2->setParent(tree2node1);
+        tree2node3->setParent(tree2node2);
+
+        leafNode->setParent(tree1node3);
+        leafNode->setParent(tree2node3);
+    }
+
+    // complex setParent from rootEntity (doesn't work QTBUG-73905)
+    // blue cylinder, top right
+    {
+        Qt3DCore::QNode *tree1node1 = new Qt3DCore::QNode(rootEntity);
+        Qt3DCore::QEntity *tree1node2 = new Qt3DCore::QEntity(rootEntity);
+        Qt3DCore::QNode *tree1node3 = new Qt3DCore::QNode(rootEntity);
+        tree1node1->setObjectName("Blue Tree1-Node1");
+        tree1node2->setObjectName("Blue Tree1-Node2");
+        tree1node3->setObjectName("Blue Tree1-Node3");
+
+        Qt3DCore::QNode *tree2node1 = new Qt3DCore::QNode(rootEntity);
+        Qt3DCore::QEntity *tree2node2 = new Qt3DCore::QEntity(rootEntity);
+        Qt3DCore::QNode *tree2node3 = new Qt3DCore::QNode(rootEntity);
+        tree2node1->setObjectName("Blue Tree2-Node1");
+        tree2node2->setObjectName("Blue Tree2-Node2");
+        tree2node3->setObjectName("Blue Tree2-Node3");
+
+        Qt3DCore::QTransform *wrongBlueTransform = new Qt3DCore::QTransform;
+        wrongBlueTransform->setTranslation(QVector3D(1, 1, 0));
+        Qt3DCore::QTransform *topRightTransform = new Qt3DCore::QTransform;
+        topRightTransform->setTranslation(QVector3D(5, 2, 0));
+        wrongBlueTransform->setObjectName("Blue Wrong Transform");
+        topRightTransform->setObjectName("Blue TR Transform");
+
+        Qt3DExtras::QPhongMaterial *blueMaterial = new Qt3DExtras::QPhongMaterial(rootEntity);
+        blueMaterial->setObjectName("Blue Material");
+        blueMaterial->setDiffuse(Qt::blue);
+        Qt3DCore::QEntity *leafNode = new Qt3DCore::QEntity(rootEntity);
+        leafNode->addComponent(mesh);
+        leafNode->addComponent(blueMaterial);
+        leafNode->setObjectName("Blue Leaf");
+
+        // sometimes this can change things
+        //QCoreApplication::processEvents();
+
+        tree1node2->addComponent(wrongBlueTransform);
+        tree2node2->addComponent(topRightTransform);
+
+        tree1node1->setParent(rootEntity);
+        tree1node2->setParent(tree1node1);
+        tree1node3->setParent(tree1node2);
+
+        tree2node1->setParent(rootEntity);
+        tree2node2->setParent(tree2node1);
+        tree2node3->setParent(tree2node2);
+
+        leafNode->setParent(tree1node3);
+        leafNode->setParent(tree2node3);
+    }
+
+    return app.exec();
+}