Add support for tiled rendering.

[brugger1]

Description

I added support for tiled rendering when doing rendering in the engine. Tiled rendering is always enabled with a default tile width and height of 8192. The reason for always being enabled is that Mesa stops working properly somewhere between an image width and height of 8192 and 16384. This avoids that issue.

The tiled rendering width and height can be controlled with the tiledRenderingWidth and tiledRenderingHeight fields in the RenderingAttributes. For example:

renderAtts = RenderingAttributes()
renderAtts.tiledRenderingWidth = 512
renderAtts.tiledRenderingHeight = 512
SetRenderingAttributes(renderAtts)

sets the tiled rendering width and height to 512.

Internally, a fixed tile size is used that just covers the image being rendered that is smaller than the user selected size. For example, if the image size is 1024x1024 and the user selects a 512x512 tile size, then it uses the user selected tile size. If the tile size doesn't exactly divide the image size, then the tile size is chosen such that last tile in each direction will minimally extend beyond the image. For example, if the image size is 1021x1021 and the user selects a 512x512 tile size, then it uses a tile size of 511x511 and discards a row and/or column in the tiles along the right and bottom edges.

In order to add support for tiled rendering for annotations, the foreground view was changed as follows.

    vtkCamera *cam = foreground->GetActiveCamera();
    cam->SetFocalPoint(0.5, 0.5, 0.);
    cam->SetPosition(0.5, 0.5, 1.);
    cam->SetViewUp(0., 1., 0.);
    cam->SetParallelProjection(1);
    cam->SetParallelScale(0.5);
    foreground->SetActiveCamera(cam);

3D annotations worked fine with this change, but 2D annotations were all rendered in NormalizedViewport coordinates. The 2D annotations were all modified to use World coordinates.

Type of change

• New feature~~

How Has This Been Tested?

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Checklist:

• I have commented my code where applicable.~~
• I have updated the release notes.~~
• I have made corresponding changes to the documentation.~~
• I have added debugging support to my changes.~~
• I have added tests that prove my fix is effective or that my feature works.~~
• I have confirmed new and existing unit tests pass locally with my changes.~~
• I have added new baselines for any new tests to the repo.~~
• I have NOT made any changes to protocol or public interfaces in an RC branch.~~