Multiple rendering windows, not all visible? Topic is solved

[jwwalker]

In the sample programs, rendering is done by Demo::GraphicsSystem::update which basically says

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if (mRenderWindow->isVisible()) mRoot->renderOneFrame();

What if I have multiple windows, and maybe some are visible and some are not? Do I go ahead and call renderOneFrame and maybe let it waste time rendering invisible things? I assume I should have only one Ogre::Root object in my application.

[dark_sylinc]

Hi!

That's correct, if at least one of them is visible then you have to call renderOneFrame.

Compositor setups can be simple to arbitrarily complex. You can individually disable workspaces to avoid rendering to specific windows (assuming you have 1 workspace per render window, like I said... your setup can be arbitrarily complex);

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workspaceForThatWindow->setEnabled( mRenderWindow->isVisible() );

This will save you some GPU & CPU work.

Cheers
Matias

[jwwalker]

Thanks, that sounds fine, except it's not obvious to me how to associate a window and a workspace. I don't see any methods on Window where you specify a CompositorWorkspace or anything like that.

[dark_sylinc]

Hi!

When you call addWorkspace there is a parameter to specify one or multiple TextureGpu as "external" targets.

Later inside the compositor your workspace and nodes will define what they do with these external targets (usually its because either you want to render to them; or because its a temporary target you want to share with all workspaces to save memory)

e.g.

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compositorManager->addWorkspace( mSceneManager, mRenderWindow->getTexture(), mCamera, workspaceName, true )

As for "how it's associated" depends on what you do. You could for example create a workspace definition that renders to multiple render windows at once (IMHO that would be crazy but that's up to you). Multiple workspaces may also draw to the same Render Window if you want (I never tried that though, I suspect it could have issues in Vulkan?) e.g.

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CompositorChannelVec externalTagets;
externalTagets.push_back( window0->getTexture() );
externalTagets.push_back( window1->getTexture() );
externalTagets.push_back( window2->getTexture() );
compositorManager->addWorkspace( mSceneManager, externalTagets, mCamera, workspaceName, true )

or you could do 1 workspace per window.

So it's not so much that as that you tell "a Render Window to have a CompositorWorkspace associated to it" but rather you grabbed a CompositorWorkspace and told it to output into the TextureGpu associated with that window.

For more info see the Compositor section.