Overlays between viewports (see picture)

[toglia]

Hi,

I was just wondering if it would be easy to implement? Has anybody had ever done this? I would aprecciate any help, hint (or snippet )


Thanks!

[jacobb]

I think you could use a RenderTargetListener to position the overlay in each viewport befores it is updated. Move it to left edge of one viewport before it's updated, and move it to the right edge of the other before it's updated, would make it appear to be in between the two.

hope it helps

[ahmadi]

Its simple just use half of the star as first overlay, and another half of the star as second overlay.
if the star shape are generated at runtime, you can also split it.

[shadowfeign]

ok, so I know nothing about viewports or overlays, but I thought I would toss this in since it might be a different direction, and I think it would work? is it possible to have viewports inside other viewports? how are things like rearview mirrors done for racing games? I think you could do something like that, have the two side panels inside one, and the overlay is above those two in that same viewport

[nbeato]

Why don't you just put the star in a different viewport that covers the entire screen? Just make it's zorder higher than the other 2 and it will render after them.

EDIT: sorry I didn't see shadowfeign's response. Yes that works, consider what he said (and what I said).

[madmarx]

I'll say the same as the other : just put it in another viewport, it's very easy.
But I'll add some snippet :


at the creation level

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Ogre::SceneManager* lSceneManager = mRoot->createSceneManager(Ogre::ST_GENERIC,"monPremierSceneManager");

	Ogre::Camera* lCamera = lSceneManager->createCamera("maPremiereCamera");

	Ogre::SceneNode * lNodeCamera = lSceneManager->getRootSceneNode()->createChildSceneNode("nodeDeMaPremiereCamera");
	lNodeCamera->attachObject(lCamera);

	// first viewport
	Ogre::Viewport * vp = mWindow->addViewport(lCamera,100, 0.1, 0.1, 0.4, 0.8);

	// second viewport
	Ogre::Viewport * vp2 = mWindow->addViewport(lCamera,80, 0.5, 0.1, 0.4, 0.8);

	// overlay viewport on top of everything
	Ogre::SceneManager *scMagrOverlay = mRoot->createSceneManager(Ogre::ST_GENERIC,"OverlayOnly_SceneManager");
	Ogre::Camera* lCamOverlay = scMagrOverlay->createCamera("maCam");
	Ogre::Viewport * vpOverlay = mWindow->addViewport(lCamOverlay,50, 0.1, 0.1, 0.8, 0.8);
	
        vpOverlay->setBackgroundColour(Ogre::ColourValue(0,0,0));
	vpOverlay->setClearEveryFrame(false);// you 'll need it in order not to overwrite everything.
	vpOverlay->setOverlaysEnabled(true);
	vpOverlay->setSkiesEnabled(false); // you don't want skies /scene to pollute your rendering.

	vp->setOverlaysEnabled(false);
	vp2->setOverlaysEnabled(false);
	
        mWindow->setActive(true);
	mWindow->setAutoUpdated(false); // I prefer manual updating.

edit : overlay creation:

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{
		Ogre::Overlay * lOverlay = Ogre::OverlayManager::getSingleton().create("Overlay/RttSceneTete");
		Ogre::OverlayContainer * lOverlaySuperContainer = dynamic_cast<Ogre::OverlayContainer*>       (Ogre::OverlayManager::getSingleton().createOverlayElement("Panel","Overlay/RttSceneTete/SuperContainer",false));
		lOverlaySuperContainer->setParameter("transparent","true"); // il est invisible (pas de material).
		lOverlaySuperContainer->show();// si on veut voir ses "enfants", il faut que lui meme soit 'visible'.
		lOverlay->add2D(lOverlaySuperContainer);

		{
			Ogre::TextAreaOverlayElement * lTextOverlay = dynamic_cast<Ogre::TextAreaOverlayElement*>(Ogre::OverlayManager::getSingleton().createOverlayElement("TextArea","Overlay/RttSceneTete/legende",false));

			lTextOverlay->setLeft(0.40);
			lTextOverlay->setWidth(0.3);
			lTextOverlay->setTop(0.3);
			lTextOverlay->setHeight(0.08);								

			lTextOverlay->setColour(Ogre::ColourValue(1,0,0,1));		// la couleur de font
			lTextOverlay->setFontName("BlueHighway");					// la font
			lTextOverlay->setCaption("THIS OVERLAY IS IN A THIRD VIEWPORT");	// le texte dans cette area
			lTextOverlay->setCharHeight(0.08);							// hauteur des lettres par rapport a l'overlay parent
			lTextOverlay->show();

			lOverlaySuperContainer->addChild(lTextOverlay);
		}
		lOverlay->show();
	}

and then when using it:

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// time to render!
			vp->update(); 
			vp2->update();
			vpOverlay->update();
// just swapping the buffers.
			mWindow->swapBuffers(true);

// call frame listeners etc...
			mRoot->renderOneFrame();

OT : how do you attach a picture in your post on ogres forum (you can pm me)?

[toglia]

Ok, thanks for all the replies. The star was just an example, the thing is that I see very common on games with split screen to use overlays that don't seem to be bothered by the viewports limits.

Right now I can't try your solution cause I'm at work, but I remember some time ago trying to overlap viewports with different z orders and what I never could do was to transparent the background of them, if I assigned a black background with 0 alpha, that didn't seem to blend them...

I even posted a new topic trying to look for a way to do transparent viewports and didn't recieve much replies...
http://www.ogre3d.org/forums/viewtopic.php?p=286341

[madmarx]

My solution (just above) is using 'transparent' viewport on top of 2 others.

I posted full code, I don't see want you want more?!

I wanted to post a picture where you can see clearly the text of the overlay in red, and the background that is from the 2 other viewports... but I don't know how to share images on the internet.

[toglia]

Lol! I didn´t look the code thoroughly. I see you change some parameters. I was looking for that like a couple months ago!!! Awesome.

Check this free Image hosting:
http://www.imageshack.us/
Have never used it, but it's on googles top list.

[toglia]

Ok, so basically to make the viewport transparent the most important command is:

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setClearEveryFrame(false);

I was setting it to true...

[madmarx]

Not exactly,

what you want is :

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viewport->setClearEveryFrame(true, FBT_DEPTH);

which means that the depth buffer is cleaned but not the color buffer.
In your case, setClearEveryFrame(false); was quickier to execute because you don't have more 3D.

But if you want to merge viewport with 3D content , you need

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viewport->setClearEveryFrame(true, FBT_DEPTH);

And if you also happen to use stencil buffer ( from stencil shadows/volumetric shadows):

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viewport->setClearEveryFrame(true, FBT_DEPTH|FBT_STENCIL);

Hope this helps!

[scrawl]

Sorry to dig up the old thread, but I've used this solution fine in Ogre 1.7, but in Ogre 1.8 trunk it doesn't work anymore. I can't see the 3d scene anymore, just the background color of viewport.

Has anyone successfully used this with ogre 1.8?