Feature request: other image projections

[MortRouge]

Hello there, I'm a long time lurker and fan of the project!

Recently, I pieced together a triple monitor setup for my computer with some old 16:10 screens, thinking that "ultra widescreen support" meant more than just allowing the resolutions to be rendered by the games.

Enter the problem with using simple Rectilinear projection. Horrible distortions in the peripheral screens. Now, often this is not a problem, because you are centering the attention on the middle screen and the rest on the sides is just a bonus.

But for playing simulations or playing games where you want to appreciate the landscape and don't fix your head in one position, it is lacking considering there are alternate ways of projection that can be used to mitigate the distortions.

Some neat visualization of different projections:
http://shaunlebron.github.io/visualizing-projections/

Here is the same person's code to create these projections in Quake 1, which some of you surely have seen before:
https://github.com/shaunlebron/blinky

Wouldn't it be interesting if the engine would be able to handle different projections, both for ultra-widescreen monitor use and for future applications inside VR (which also needs to adjust the projection)?

[wareya]

This is hard for 3d games in general because rectilinear projection is used specifically because it trivializes rasterization. The only way to implement alternate projections on something like OpenGL3 is to use a post-processing shader that reprojects the image, which is possible, but requires oversampling if it's going to not cause bad upscaling blur in the center of the screen. This oversampling makes it very expensive because you're basically doing the same thing as SSAA at the end of the day.

[raven]

I think your specific use case (multiple screens) should be easy to support, by enabling the functionality in osg and adding options to set up the additional screens. Each screen would still be using rectilinear projection. But with a reduced screen fov it should be good enough.