Add infrastructure for doc generation

Added the doc config for the Quick 3D module,
with index and module pages for C++ and QML types.
Also added bare min. docs for a few C++ and QML
types, and a group page for the examples.

src/quick3d/doc/QtQuick3DDoc

+#include <QtQuick3d>
\ No newline at end of file

src/quick3d/doc/quick3d.qdocconf

+include($QT_INSTALL_DOCS/global/qt-module-defaults.qdocconf)
+
+project                 = QtQuick3D
+description             = Qt Quick 3D Reference Documentation
+version                 = $QT_VERSION
+
+examplesinstallpath     = quick3d
+
+# Custom module header that pulls in also QtQuickWidgets
+moduleheader            = QtQuick3DDoc
+includepaths            = -I .
+
+qhp.projects            = QtQuick3D
+
+qhp.QtQuick.file                = qtquick3d.qhp
+qhp.QtQuick.namespace           = org.qt-project.qtquick3d.$QT_VERSION_TAG
+qhp.QtQuick.virtualFolder       = qtquick3d
+qhp.QtQuick.indexTitle          = Qt Quick 3D
+qhp.QtQuick.indexRoot           =
+
+qhp.QtQuick3D.filterAttributes    = qtquick3d $QT_VERSION qtrefdoc
+qhp.QtQuick3D.customFilters.Qt.name = QtQuick3D $QT_VERSION
+qhp.QtQuick3D.customFilters.Qt.filterAttributes = qtquick3d $QT_VERSION
+qhp.QtQuick3D.subprojects         = qmltypes classes examples
+qhp.QtQuick3D.subprojects.qmltypes.title = QML Types
+qhp.QtQuick3D.subprojects.qmltypes.indexTitle = Qt Quick 3D QML Types
+qhp.QtQuick3D.subprojects.qmltypes.selectors = qmlclass
+qhp.QtQuick3D.subprojects.qmltypes.sortPages = true
+qhp.QtQuick3D.subprojects.classes.title = Classes
+qhp.QtQuick3D.subprojects.classes.title = C++ Classes
+qhp.QtQuick3D.subprojects.classes.indexTitle = Qt Quick 3D C++ Classes
+qhp.QtQuick3D.subprojects.classes.selectors = class fake:headerfile
+qhp.QtQuick3D.subprojects.classes.sortPages = true
+qhp.QtQuick3D.subprojects.examples.title = Examples
+qhp.QtQuick3D.subprojects.examples.indexTitle = Qt Quick 3D Examples and Tutorials
+qhp.QtQuick3D.subprojects.examples.selectors = fake:example
+
+tagfile                 = ../../../doc/qtquick3d/qtquick3d.tags
+
+depends += qtqml qtquick qtdoc
+
+headerdirs  += ..
+
+sourcedirs  += .. \
+               src  
+
+exampledirs +=  ../../../examples/quick3d
+
+imagedirs   += images
+
+#add imports directory because of dependencies
+headerdirs += ../../imports
+sourcedirs += ../../imports
+
+#add plugins directory because of dependencies
+headerdirs += ../../plugins
+sourcedirs += ../../plugins
+
+navigation.landingpage = "Qt Quick 3D"
\ No newline at end of file

src/quick3d/doc/src/qtquick3d-examples.qdoc

+/*!
+    \group quick3d-examples
+    \title Qt Quick 3D Examples and Tutorials
+    \brief List of all examples and tutorials
+*/
+/*!
+    \example hellocube
+    \title Qt Quick 3D - Hellocube example
+    \brief Demonstrates the use of custom material
+    \ingroup quick3d-examples
+
+    \image hellocube.png
+*/

src/quick3d/doc/src/qtquick3d-index.qdoc

+/*!
+\page qtquick3d-index.html
+\title Qt Quick 3D
+\brief Provides API that lets you define 3D items using QML
+
+Qt Quick 3D provides a high-level API for creating 3D content or UIs based on
+Qt Quick. Rather than using an external engine which creates syncing issues,
+and additional layers of abstraction, we provide extensions to the existing
+Qt Quick scenegraph for spatial content, and a renderer for that extended
+scenegraph. When using the Spatial scenegraph it is also be possible to mix
+Qt Quick 2D content with 3D content.
+
+\image demoRender.png
+
+\section1 Related information
+
+\list
+\li \l{Qt Quick 3D C++ Classes}
+\li \l{Qt Quick 3D QML Types}
+\li \l{Qt Quick 3D Examples and Tutorials}
+\endlist
+*/

src/quick3d/doc/src/qtquick3d-module.qdoc

+/*!
+\module QtQuick3D
+\title Qt Quick 3D C++ Classes
+\brief Provides the necessary C++ classes to include 3D items.
+
+\omit
+TODO: Add necessary information to use the module.
+\endomit
+*/

src/quick3d/doc/src/qtquick3d-qmlmodule.qdoc

+/*!
+\qmlmodule QtDemon 1.0
+\title Qt Quick 3D QML Types
+\brief Provides the QML types to include 3D items.
+
+This is the QML frontend for using the spatial renderer and scenegraph. For the
+time being, all 3D content goes through offscreen textures (FBO)s so that they
+can be composed into Qt Quick scenes (as a QQuickItem).
+
+*/

src/quick3d/qdemoncamera.cpp

@@ -5,7 +5,11 @@
 #include <QtMath>
 
 QT_BEGIN_NAMESPACE
-
+/*!
+    \qmltype DemonCamera
+    \inqmlmodule QtDemon
+    \brief Lets you add a camera to view the 3D content
+*/
 QDemonCamera::QDemonCamera() {}
 
 float QDemonCamera::clipNear() const

src/quick3d/qdemondefaultmaterial.cpp

@@ -4,6 +4,11 @@
 
 QT_BEGIN_NAMESPACE
 
+/*!
+    \qmltype DemonDefualtMaterial
+    \inqmlmodule QtDemon
+    \brief Lets you define material for the 3D item
+*/
 QDemonDefaultMaterial::QDemonDefaultMaterial()
     : m_diffuseColor(Qt::white)
     , m_emissiveColor(Qt::white)

src/quick3d/qdemonimage.cpp

@@ -5,7 +5,11 @@
 #include "qdemonobject_p.h"
 
 QT_BEGIN_NAMESPACE
-
+/*!
+    \qmltype DemonImage
+    \inqmlmodule QtDemon
+    \brief Lets you add a texture image to the material
+*/
 QDemonImage::QDemonImage() {}
 
 QDemonImage::~QDemonImage() {}

src/quick3d/qdemonlight.cpp

@@ -4,6 +4,12 @@
 
 QT_BEGIN_NAMESPACE
 
+/*!
+    \qmltype DemonLight
+    \inqmlmodule QtDemon
+    \brief Lets you define the lighting for a 3D item
+*/
+
 QDemonLight::QDemonLight() : m_diffuseColor(Qt::white), m_specularColor(Qt::white), m_ambientColor(Qt::black) {}
 
 QDemonLight::~QDemonLight() {}

src/quick3d/qdemonmodel.cpp

@@ -11,6 +11,11 @@
 
 QT_BEGIN_NAMESPACE
 
+/*!
+   \qmltype DemonModel
+   \inqmlmodule QtDemon
+   \brief Lets you load a 3D model data
+*/
 QDemonModel::QDemonModel() {}
 
 QDemonModel::~QDemonModel() {}

src/quick3d/qdemonnode.cpp

@@ -7,6 +7,11 @@
 
 QT_BEGIN_NAMESPACE
 
+/*!
+    \qmltype DemonNode
+    \inqmlmodule QtDemon
+    \brief Lets you define a 3D item with necessary properties
+*/
 QDemonNode::QDemonNode()
 {
     // Update global transform properties from backend

src/quick3d/qdemonsceneenvironment.cpp

@@ -28,6 +28,11 @@ static void updateProperyListener(QDemonObject *newO, QDemonObject *oldO, QDemon
     }
 }
 
+/*!
+    \qmltype DemonSceneEnvironment
+    \inqmlmodule QtDemon
+    \brief Lets you configure the scene environment
+*/
 QDemonSceneEnvironment::QDemonSceneEnvironment(QDemonObject *parent)
     : QDemonObject(parent)
 {

src/quick3d/qdemonview3d.cpp

@@ -38,6 +38,18 @@ QT_BEGIN_NAMESPACE
 //        connections.insert(newO, connection);
 //    }
 //}
+/*!
+    \class QDemonView3D
+    \inmodule QtQuick3D
+    \brief Provides the infrastructure to render 3D items
+
+*/
+/*!
+    \qmltype DemonView3D
+    \inqmlmodule QtDemon
+    \brief Provides the infrastructure to render 3D items
+
+*/
 
 QDemonView3D::QDemonView3D(QQuickItem *parent)
     : QQuickItem(parent)

src/quick3d/quick3d.pro

@@ -5,6 +5,8 @@ QT = core-private gui-private demonruntimerender-private quick-private
 
 DEFINES += QT_BUILD_QUICK3D_LIB
 
+QMAKE_DOCS = $$PWD/doc/quick3d.qdocconf
+
 SOURCES += \
     qdemonobject.cpp \
     qdemonnode.cpp \