Doc: Describe the Loader3D component

Task-number: QDS-4888
Change-Id: Ia05b374f79030613ce68bfa70950e503cd83d454
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>

doc/qtcreator/src/qtcreator-toc.qdoc

@@ -146,6 +146,7 @@
                                 \li \l{Scene Environment}
                                 \li \l{Morph Target}
                                 \li \l{Repeater3D}
+                                \li \l{Loader3D}
                             \endlist
                         \li \l {Creating Component Instances}
                         \li \l {Creating Custom Components}

doc/qtcreator/src/qtquick/library/qtquick-component-instances.qdoc

@@ -25,7 +25,7 @@
 
 /*!
     \page quick-component-instances.html
-    \previouspage studio-3d-repeater-3d.html
+    \previouspage studio-3d-loader-3d.html
     \nextpage quick-components-creating.html
 
     \title Creating Component Instances

doc/qtcreator/src/qtquick/library/qtquick-preset-components.qdoc

@@ -84,6 +84,7 @@
         \li \l {Scene Environment}
         \li \l {Morph Target}
         \li \l {Repeater3D}
+        \li \l {Loader3D}
      \endlist
 
     When you import 3D scenes from files that you exported from 3D graphics

doc/qtdesignstudio/src/qtdesignstudio-toc.qdoc

@@ -103,6 +103,7 @@
                                 \li \l{Scene Environment}
                                 \li \l{Morph Target}
                                 \li \l{Repeater3D}
+                                \li \l{Loader3D}
                             \endlist
                         \li \l {Creating Component Instances}
                         \li \l {Creating Custom Components}

doc/qtdesignstudio/src/qtquick3d-editor/qtdesignstudio-3d-loader-3d.qdoc

@@ -0,0 +1,110 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Design Studio.
+**
+** $QT_BEGIN_LICENSE:FDL$
+** 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 Free Documentation License Usage
+** Alternatively, this file may be used under the terms of the GNU Free
+** Documentation License version 1.3 as published by the Free Software
+** Foundation and appearing in the file included in the packaging of
+** this file. Please review the following information to ensure
+** the GNU Free Documentation License version 1.3 requirements
+** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+    \page studio-3d-loader-3d.html
+    \previouspage studio-3d-repeater-3d.html
+    \nextpage quick-component-instances.html
+
+    \title Loader3D
+
+    \note The \uicontrol Loader3D component is released as a tech preview
+    feature in \QDS 2.2, and its functionality will be improved in future
+    releases.
+
+    \uicontrol Loader3D is a loader component used to dynamically load 3D
+    components. It can load a QML file using the \uicontrol Source property or a
+    component using the \uicontrol {Source component} property. \uicontrol Loader3D
+    is useful for delaying the creation of a component until it is required, for
+    example, when a component should be created on demand or when a component
+    should not be created unnecessarily for performance reasons.
+
+    Add a \uicontrol Loader3D component to your scene by drag-and-dropping it
+    from \uicontrol Library > \uicontrol Components > \uicontrol {Qt Quick 3D} >
+    \uicontrol {Qt Quick 3D} to \uicontrol Scene in \uicontrol Navigator.
+
+    For more information, see the \l{https://doc.qt.io/qt/qml-qtquick3d-loader3d.html}
+    {Loader3D QML type} in the \uicontrol {Qt Quick 3D} documentation.
+
+    \section1 Loader3D Properties
+
+    Select the \uicontrol Loader3D component in \uicontrol Navigator to specify
+    its properties in \uicontrol Properties > \uicontrol Loader3D.
+
+    \image studio-3d-loader3d-properties.png "Loader3D specific properties"
+
+    The \uicontrol Active property is set to \uicontrol true by default, which
+    makes the \uicontrol Loader3D currently active. Setting \uicontrol Active to
+    \uicontrol false makes \uicontrol Loader3D inactive. If you change the
+    \uicontrol Source or \uicontrol {Source component} of an inactive
+    \uicontrol Loader3D, the component will not be instantiated until
+    \uicontrol Loader3D is made active. Setting \uicontrol Loader3D inactive
+    will also cause any item loaded by the loader to be released, but this will
+    not affect the files or components defined as \uicontrol Source or
+    \uicontrol {Source component}.
+
+    Use the dropdown menu of the \uicontrol Source property to define the URL of
+    the 3D component to instantiate. To unload the currently loaded object, set
+    this property to an empty string or set the \uicontrol {Source component} to
+    undefined. Setting \uicontrol Source to a new URL will also cause the item
+    created by the previous URL to be unloaded.
+
+    The \uicontrol {Source component} property defines the component for
+    \uicontrol Loader3D to instantiate. Currently, the
+    \uicontrol {Source component} needs to be defined in code using the
+    \l {Working in Edit Mode}{Edit} mode or \l {Text Editor}.
+
+    Set the \uicontrol Asynchronous property to define whether the component
+    will be instantiated asynchronously. This property is set to \uicontrol false
+    by default. When used in conjunction with the source property, loading and
+    compilation will be performed in a background thread. Loading asynchronously
+    creates the objects declared by the component across multiple frames and
+    reduces the likelihood of glitches in animation. Setting the value of
+    \uicontrol Asynchronous to \uicontrol false while an asynchronous load is in
+    progress will force immediate synchronous completion. This allows an
+    asynchronous loading to begin and then forces completion if the
+    \uicontrol Loader3D content must be accessed before the asynchronous
+    loading is completed.
+
+    To avoid seeing the components loading progressively, set the \uicontrol
+    Visibility property for \uicontrol Loader3D appropriately in
+    \uicontrol {Binding Editor}:
+        \list 1
+            \li In \uicontrol Properties > \uicontrol Loader3D, select the
+                \uicontrol Asynchronous check box to set the property to
+                \uicontrol true.
+            \li In \uicontrol Node > \l {Setting Node Opacity and Visibility}{Visibility},
+                select \inlineimage icons/action-icon.png
+                to open the actions menu, and then select \uicontrol {Set Binding}.
+            \li Type \c {status === Loader3D.Ready} into \uicontrol {Binding Editor},
+                as shown in the image below.
+            \li Select \uicontrol OK.
+        \endlist
+
+    \image studio-3d-loader3d-binding-editor.png "Setting Visibility in Binding Editor"
+
+*/

doc/qtdesignstudio/src/qtquick3d-editor/qtdesignstudio-3d-repeater-3d.qdoc

@@ -28,7 +28,7 @@
 /*!
     \page studio-3d-repeater-3d.html
     \previouspage studio-3d-morph-target.html
-    \nextpage quick-component-instances.html
+    \nextpage studio-3d-loader-3d.html
 
     \title Repeater3D
 
@@ -60,7 +60,7 @@
     For more information, see \l{https://doc.qt.io/qt/qml-qtquick3d-repeater3d.html}
     {Repeater3D} in the \uicontrol {Qt Quick 3D} documentation.
 
-    \section1 Repeater 3D Properties
+    \section1 Repeater3D Properties
 
     To define a model providing data for the repeater, select it in \l Navigator,
     and then in \uicontrol Properties > \uicontrol Repeater, specify the