[3.2] Viewport considerations

Firstly, I've noted that MyGUI doesn't take viewport dimension into account when you inject mouse events, e.g adjusting mouse position based on viewport position within the RenderWindow. Is this a bug or a feature - and do I simply roll my own code or is there a utility already in MyGUI?

Secondly, [how] can I control which viewport MyGUI is using by default?

OK, so OgreRenderManager::setActiveViewport() lets me tell it what viewport to use, neat.

How should one use MyGUI to apply a GUI in a multi-viewport application though - say I have 4 VPs splitting the screen into quarters and each should have some buttons - I need to handle both rendering and input to each viewport properly.

Why not draw GUI in main viewport above everything else, and place your controls properly above each quarter.

You can render gui in 4 viewports, but this require GUI rendered into 4 different textures for each viewport, and I see no reason how could this be useful.

You can have a viewport on top of another with transparency - e.g set alpha=0 on background-color? If so I guess you could have one full-screen viewport used only for GUI.

But that leads to bad design - your central app has to know about all the viewports and manage each viewport's associated GUI. Conceptually it's better each viewport keeps track of its own GUI - I'm using viewports in more dynamic way.

Not sure why you'd have to use 4 separate textures - although if you can point to any example/sample using multiple textures, I'd like to see it! It seems each viewport could just have a frame-listener which calls OgreRenderManager::setActiveViewport() and handles showing/hiding correct widgets, just before rendering. But this is an ugly hack. It's a shame multi-viewport support isn't built in really. It would make MyGUI much more useful for non-game applications

Why not draw GUI in main viewport above everything else, and place your controls properly above each quarter.
What I'm looking at now is using 4 Canvas controls, each taking 1/4 of the screen. Then I can easily use GUI on top, and even wrap Canvas in a parent Window so I can have GUI for each 'view'.

My main issue here is, I only want Ogre to render MyGUI into the main viewport. The Canvas objects have 3D rendering but I don't want to be rendering the 3D scene as well into the main viewport as it will be hidden by the 4 Canvas objects. I wonder what the easiest setup for that is?

e.g:
int width = renderWindow.getWidth(), height=renderWindow.getHeight();
int viewWidth=width/2, viewHeight=height/2;

for(int x=0;x<2;++x)
for(int y=0;y<2;++y)
{
widget = Gui::getInstance().createWidget<Widget>("PanelSkin",viewWidth*x,viewHeight*y,viewWidth,viewHeight);
IntCoord clientRect = widget->getClientCoord();
canvas = widget->createWidget<Canvas>("Canvas",0, 0, clientRect.width,clientRect.height,Align::Stretch);
...
}So I have my 4 views which can have different cameras, etc, and I can have my GUI... but I don't want to render anything under the GUI.

edit - since MyGUI uses Ogre Overlays, I think that question can be rephrased as "how can I make Ogre render just the overlays for a viewport and nothing else".

edit - since MyGUI uses Ogre Overlays, I think that question can be rephrased as "how can I make Ogre render just the overlays for a viewport and nothing else".MyGUI don't use overlays, but use same rendering order though. And what about your question - isn't viewport that see nothing render only overlays?

If MyGUI doesn't use overlays,why does disabling overlays on an Ogre viewport make MyGUI disappear?

Because, as I just said, MyGUI use same rendering queue group, and disabling overlays is just skipping that queue group in render process.