Doc: Describe Joint and Skeleton components

Task-number: QDS-4888
Change-Id: I9a9664cb327f2ddad2025d5c38bb2f3b1bebb887
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>
Reviewed-by: Inho Lee <inho.lee@qt.io>
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>

8 files changed, 82 insertions, 2 deletions

diff --git a/doc/qtcreator/src/qtcreator-toc.qdoc b/doc/qtcreator/src/qtcreator-toc.qdoc
index dfb84f20f7..4339674313 100644
--- a/doc/qtcreator/src/qtcreator-toc.qdoc
+++ b/doc/qtcreator/src/qtcreator-toc.qdoc
@@ -132,6 +132,7 @@
                                 \li \l{Animations}
                                 \li \l{3D Views}
                                 \li \l{Group}
+                                \li \l{Skeletal Animation}
                                 \li \l{3D Models}
                                 \li \l{Materials and Shaders}
                                 \li \l{Textures}
diff --git a/doc/qtcreator/src/qtquick/library/qtquick-preset-components.qdoc b/doc/qtcreator/src/qtquick/library/qtquick-preset-components.qdoc
index d9ac4b9387..68c1875c06 100644
--- a/doc/qtcreator/src/qtquick/library/qtquick-preset-components.qdoc
+++ b/doc/qtcreator/src/qtquick/library/qtquick-preset-components.qdoc
@@ -70,6 +70,7 @@
         \list
         \li \l {3D Views}
         \li \l {Group}
+        \li \l {Skeletal Animation}
         \li \l {3D Models}
         \li \l {Materials and Shaders}
         \li \l {Textures}
diff --git a/doc/qtcreator/src/qtquick/qtquick-library.qdoc b/doc/qtcreator/src/qtquick/qtquick-library.qdoc
index 8dc9c3c44a..ae206f3e4f 100644
--- a/doc/qtcreator/src/qtquick/qtquick-library.qdoc
+++ b/doc/qtcreator/src/qtquick/qtquick-library.qdoc
@@ -71,6 +71,7 @@
         \li \l Animations
         \li \l{3D Views}
         \li \l{Group}
+        \li \l{Skeletal Animation}
         \li \l{3D Models}
         \li \l{Materials and Shaders}
         \li \l{Textures}
diff --git a/doc/qtdesignstudio/images/studio-3d-joint-properties.png b/doc/qtdesignstudio/images/studio-3d-joint-properties.png
new file mode 100644
index 0000000000..71beb6fd3e
--- /dev/null
+++ b/doc/qtdesignstudio/images/studio-3d-joint-properties.png
diff --git a/doc/qtdesignstudio/src/qtdesignstudio-toc.qdoc b/doc/qtdesignstudio/src/qtdesignstudio-toc.qdoc
index 9442cbfd6d..ceb5d45861 100644
--- a/doc/qtdesignstudio/src/qtdesignstudio-toc.qdoc
+++ b/doc/qtdesignstudio/src/qtdesignstudio-toc.qdoc
@@ -89,6 +89,7 @@
                                 \li \l Animations
                                 \li \l{3D Views}
                                 \li \l{Group}
+                                \li \l{Skeletal Animation}
                                 \li \l{3D Models}
                                 \li \l{Materials and Shaders}
                                 \li \l{Textures}
diff --git a/doc/qtdesignstudio/src/qtquick3d-editor/qtdesignstudio-3d-model.qdoc b/doc/qtdesignstudio/src/qtquick3d-editor/qtdesignstudio-3d-model.qdoc
index 2a7b346d60..26d0685296 100644
--- a/doc/qtdesignstudio/src/qtquick3d-editor/qtdesignstudio-3d-model.qdoc
+++ b/doc/qtdesignstudio/src/qtquick3d-editor/qtdesignstudio-3d-model.qdoc
@@ -27,7 +27,7 @@
 
 /*!
     \page studio-3d-model.html
-    \previouspage studio-3d-node.html
+    \previouspage studio-skeletal-components.html
     \nextpage studio-3d-materials.html
 
     \title 3D Models
diff --git a/doc/qtdesignstudio/src/qtquick3d-editor/qtdesignstudio-3d-node.qdoc b/doc/qtdesignstudio/src/qtquick3d-editor/qtdesignstudio-3d-node.qdoc
index 701683979c..9c50ec4232 100644
--- a/doc/qtdesignstudio/src/qtquick3d-editor/qtdesignstudio-3d-node.qdoc
+++ b/doc/qtdesignstudio/src/qtquick3d-editor/qtdesignstudio-3d-node.qdoc
@@ -26,7 +26,7 @@
 /*!
     \page studio-3d-node.html
     \previouspage quick-animations.html
-    \nextpage studio-3d-model.html
+    \nextpage studio-skeletal-components.html
 
     \title Group
 
diff --git a/doc/qtdesignstudio/src/qtquick3d-editor/studio-skeletal-components.qdoc b/doc/qtdesignstudio/src/qtquick3d-editor/studio-skeletal-components.qdoc
new file mode 100644
index 0000000000..c6edcc7197
--- /dev/null
+++ b/doc/qtdesignstudio/src/qtquick3d-editor/studio-skeletal-components.qdoc
@@ -0,0 +1,76 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt Design Studio documentation.
+**
+** 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.
+**
+****************************************************************************/
+
+/*!
+    \page studio-skeletal-components.html
+    \previouspage studio-3d-node.html
+    \nextpage studio-3d-model.html
+
+    \title Skeletal Animation
+
+    Skeletal animation is a technique used in computer animation. In skeletal
+    animation, a character is represented in the form of a surface representation
+    (skin or mesh), and a skeleton. This portrays how the character can move,
+    inspired by how a physical skeleton works for vertebrates. The "bones" of the
+    skeleton are represented by a hierarchy of joint nodes.
+
+    The normal workflow is to use an external content creation tool to define
+    the skeleton and the skin (this is sometimes also referred to as rigging),
+    and import them to \QDS. You can then create skeletal animations using
+    \uicontrol Skeleton and \uicontrol Joint components available in
+    \uicontrol Library > \uicontrol Components > \uicontrol {Qt Quick 3D} >
+    \uicontrol {Qt Quick 3D}.
+
+    \section1 Skeleton
+
+    A \uicontrol Skeleton component determines a skeletal animation hierarchy
+    and defines how a model can be animated using skeletal animation.
+    It contains a hierarchy of \uicontrol Joint nodes. Each joint can be
+    transformed for a skinning animation.
+
+    \section1 Joint
+
+    A \uicontrol Joint defines a node in a skeletal animation hierarchy
+    and functions similarly to joints between bones in a human skeleton.
+    It is a transformable node that must be contained inside a
+    \uicontrol Skeleton component.
+
+    Define properties for \uicontrol Joint components in \uicontrol Properties
+    > \uicontrol Joint.
+
+    \image studio-3d-joint-properties.png "Joint properties in the Properties view"
+
+    Use the \uicontrol Index property to define the index of this joint.
+    This index value is used in the \uicontrol {Joint semantic} custom geometry
+    attribute.
+
+    \note The \uicontrol Index values must be unique within the same
+    \uicontrol Skeleton.
+
+    Use the \uicontrol {Skeleton root} property to define the \uicontrol Skeleton
+    that contains the \uicontrol Joint. Do note that all the \uicontrol Joints
+    in the \uicontrol Skeleton must have the same \uicontrol {Skeleton root}
+    for the animation to work properly.
+*/