Doc: Add documentation about baking lightmaps

Task-number: QDS-9519
Change-Id: Ibe91546a14f074eb7ff489e21c36676f23b74cbb
Reviewed-by: Esa Törmänen <esa.tormanen@qt.io>
Reviewed-by: Mats Honkamaa <mats.honkamaa@qt.io>

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

@@ -208,4 +208,97 @@
     To specify the maximum distance for the shadow map, set the
     \uicontrol {Shadow map far} property value. Using smaller values
     may improve the precision and effects of the map.
+
+    \section1 Baking Lightmaps
+
+    \note Lightmaps baking is released as technical preview in \QDS 4.1.
+
+    \section2 Baking Lightmaps for a 3D Model
+    Baked lightmap components are not visible in the \uicontrol Navigator view by default. To make
+    them visible, select \inlineimage icons/visibilityon.png
+    in the \uicontrol Navigator view.
+
+    To bake lightmaps for a 3D model:
+    \list 1
+      \li From \uicontrol Components, drag a \uicontrol {Baked Lightmap} component to
+      the 3D model in the \uicontrol Navigator view.
+      \image baked-lightmaps-navigator.png
+      \li In the \uicontrol Navigator view, select \e bakedLightmap and in the \uicontrol Properties
+      view:
+        \list
+          \li Select \uicontrol Enabled.
+          \li In \uicontrol Key, set the filename base for the generated light maps. This must be
+          a unique name.
+          \li In \uicontrol {Load Prefix}, set the relative path to the folder where the generated
+          light map files are saved.
+        \endlist
+      \li In the \uicontrol Navigator view, select the 3D model and in the \uicontrol Properties
+      view, select \uicontrol {Used in Baked Lighting}.
+      \li Optional. Adjust \uicontrol Resolution to set the light map resoution. This effects how
+      accurate and time-consuming the lightmap baking is.
+      \li In the \uicontrol Navigator view, select the light component that you want to bake
+      lightmaps for, and in the \uicontrol Properties view, set \uicontrol {Bake Mode} to BakeModeAll.
+      \li Right-click anywhere in the \uicontrol 3D view and select \uicontrol {Bake Lights}.
+    \endlist
+
+    \section2 Baking Lightmaps for a 3D Model Inside a Sub Component
+
+    To bake lightmaps for a 3D model inside a sub component, first add a local custom property to
+    expose the model:
+
+    \list 1
+      \li In the \uicontrol Navigator view, right-click the sub component and select
+      \uicontrol {Edit Component}.
+      \image baked-lightmaps-edit-component.png
+      \li In the \uicontrol Navigator view, select the root component.
+      \li In the \uicontrol Properties view, select \inlineimage icons/plus.png
+      in the \uicontrol {Local Custom Properties} section.
+      \li Add a new property, set \uicontrol Type to alias.
+      \image baked-lightmaps-add-property.png
+      \li For the property, set the value to the ID of the 3D model that you want
+      to bake lightmaps for.
+      \image baked-lightmaps-property-value.png
+      \li In the \uicontrol Navigator view, select the 3D model and in the \uicontrol Properties
+      view:
+        \list
+          \li Select \uicontrol {Used in Baked Lighting}.
+          \li Set \uicontrol Resolution to, for example, 128.
+        \endlist
+      \li Save your changes (\key {Ctrl+S}) and return to the main project file. To do this, select
+      the bread crumb in the top toolbar.
+      \image baked-lightmaps-exit-component.png
+      \li From the \uicontrol Components view, drag a \uicontrol {Baked Lightmap} component to the
+      sub component in the \uicontrol Navigator view.
+      \image baked-lightmaps-navigator-blm.png
+      \li In the \uicontrol Navigator view, select the sub component and go to the
+      \uicontrol Code view.
+      \li In the \uicontrol Code view, you need to set the properties for the model inside the sub
+      component by using the exposed property.
+
+      Add the following code inside the sub component.
+      \code
+          lmSphere.bakedLightmap: bakedLightmap
+      \endcode
+
+      It should look something like this:
+      \code
+          MyGroup {
+            id: group
+            lmSphere.bakedLightmap: bakedLightmap
+            BakedLightmap {
+              id: bakedLightmap
+              loadPrefix: "lightmaps"
+              }
+            }
+      \endcode
+      \li In the \uicontrol Navigator view, select \e bakedLightMap, and in the \uicontrol
+      Properties view:
+        \list
+          \li Select \uicontrol Enabled.
+          \li In \uicontrol Key, set the filename base for the generated light maps. This must be
+          a unique name.
+        \endlist
+      \li Right-click anywhere in the \uicontrol 3D view and select \uicontrol {Bake Lights}.
+    \endlist
+
 */