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openglsshx11nvidiax11-forwarding
Kaihong Zhang
Kaihong Zhang

Reputation: 419

How can I xforwarding openGL applications from server

I have a server with nvidia graphics card, and I want to run some openGL applications and xforwarding the display to client.

How can I achieve this? Currently I have not installed X window System yet.

Upvotes: 3

Views: 7468

Answers (1)

datenwolf
datenwolf

Reputation: 162307

X forwarding means, that all rendering commands are encapsulated into the X transport and transferred over to the machine with the display and executed there. The upside is, that the remote end does not require a GPU whatsoever. The downside is, that it consumes (well, rather gobbles up) lots of network bandwidth.

OpenGL up to version 2.1 specifies GLX opcodes for the X11 transport, so is network transparent. And if you make liberal use of display lists and keep the amount of data transferred small (i.e. no client side vertex array, only a few and little textures), OpenGL-over-GLX-over-X11-over-TCP works rather fine.

However these days it's more efficient to render remotely and only transfer the generated image using a high efficiency compression codec. Plain X11 forwarding can't do that, though. But you can do it using Xpra backed by a "true" X server, talking to an actual GPU. The problem is, that you'll need that particular X server to occupy the GPU.

A better method is, to detect if there's the GLX extension available, and if not if there's a GPU around and use that to render into a XSHM pixmap. That way also Xpra on a virtual framebuffer server will work. Unfortunately doing the later with OpenGL is annoyingly difficult to implement in a way, that it works transparently accross context creation APIs. It can be done (BT;DT) but actually for this kind of thing I actually prefer Vulkan, because despite Vulkan's verbosity it takes less work to do reliably with Vulkan than with OpenGL.

Maybe (unlikely) we'll see some X11 extension for compressed transfer of pixmaps, some high compression XV or similar. That, in combination with an pure off-screen, GPU rendering (we already have that), would make for a far more efficient system.

Upvotes: 8

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