Document dynamic layer resizing

Task-number: QT3DS-4077
Change-Id: Ia045725d76811554a2f1dc7f630abbaed5fcfe74
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>

2 files changed, 28 insertions, 0 deletions

diff --git a/doc/src/03-studio/7-inspector-palette.qdoc b/doc/src/03-studio/7-inspector-palette.qdoc
index 7ba48b9b..5310d1c5 100644
--- a/doc/src/03-studio/7-inspector-palette.qdoc
+++ b/doc/src/03-studio/7-inspector-palette.qdoc
@@ -236,6 +236,23 @@ in the Inspector palette:
   presentation and the layer, either in pixels or as a percentage of the
   presentation's height.
 \li
+  \b{Dynamic Resize} - The layer is resized dynamically based on the content.
+  This allows the layer texture to be the smallest possible in order to increase performance.
+  The texture is continuously resized as the content changes.
+\li
+  \b{Padding} - The resized layer can be padded. This lowers the amount of resizes
+  needed as the content changes. The layer is resized only when the content changes
+  so much that it exceeds the previous padded size. Padding is also used in reverse
+  to calculate the lower bounds. When the content changes to be smaller, the resize
+  only happens after it takes less space than the lower bounds. The padding can be
+  expressed in pixels or as percentage of the layer size.
+\li
+  \b{Combine Bounds} - When \c{Dynamic Resize} is in use, the bounds of the objects
+  inside the layer have to be calculated. When this property is disabled, all object
+  bounds are calculated separately and a more accurate layer resize is done based on
+  those separated bounds. When this property is enabled, the object bound calculations
+  are combined, causing more inaccurate but faster results.
+\li
   \b{Ambient Occlusion} - Enables ambient occlusion (AO).
   AO is a form of approximated global illumination which
   causes non-directional self-shadowing where objects are close
diff --git a/doc/src/layers.qdoc b/doc/src/layers.qdoc
index 6bec78dc..016ee81f 100644
--- a/doc/src/layers.qdoc
+++ b/doc/src/layers.qdoc
@@ -116,4 +116,15 @@ the order objects are rendered.
 \l{Using Variant Tags}{Variant tags} makes it possible to exclude layers during loading to
 optimize performance.
 
+\section2 Dynamic Resize
+The Dynamic Resize property causes the layer to be dynamically resized based on the content.
+This makes the layer texture as small as it can be while still showing all the content.
+Thus effects like SSAA can be done more efficiently on the layer, since the empty space around
+the content doesn't take up computing power. This can also, depending on the hardware, cause
+performance problems due to constant resizing. This can be mitigated with the Padding property.
+While resizing may cause problems on the GPU side, the content bounds calculation also takes time
+on the CPU. If more inaccurate bounds are enough, Combine Bounds can be used to have less
+calculations per object in the layer. The user has to balance the performance cost of the resize
+to the performance gain of the lower texture size when evaluating the use of this feature.
+
 */