Re: very slow drawing

Thomas Walter (twalter@physik.unizh.ch)
Sat, 6 Feb 1999 20:44:40 +0100 (CET)


>
> It seems that this discussion raises a very important issue, related to the
> design of ROOT low-level graphics.
>
> - ROOT uses raster (as opposite to vector) graphics, it is pixmaps and not
> X11 "draw primitive" commands which are being passed over the network.
> Passing pixmaps over the network is not the most time-efficient way
> of displaying the graphics images. I think that this explains the problems
> experienced by Thomas.
>
This was exactly the answer I was looking for. And with Renes straight tip
to use root in the batch-mode, I'm satisfied.

> It takes me 10 seconds and even more to redraw a simple canvas
> when I'm working from home using X-terminal over the modem (28K) connection.
> In this mode there is a drastic difference in performance between ROOT
> and PAW graphics with PAW graphics being many (5-10) times faster.
> Redrawing of more complex event displays takes minutes.
>
> - any graphics system which is required to be efficient over the network has
> to work in client-server mode with the drawing commands and not pixmaps
> travelling across the ocean. If I remember it correctly a work on the
> implementation of client-server graphics mode for ROOT has started some
> time ago but I don't know where the things stand right now. Client-server
> mode won't help people using X-terminals, but as these are becoming less
> and less popular, I don't think it is a serious issue.
>
This would be a big improvement.

> - several big experiments (with Tevatron experiments among them) are planning
> to take data in the year of 2000, there definitely
> be a lot of physicists using event display programs in the distributed
> environment (over the LAN's and WAN's), the issue of performace is a very
> important one, so it make sense to have a special discussion of client-server
> graphics mode at the ROOT user workshop planned at Fermilab in the end of March.
>
> -pasha
>

Thanks a lot to everybody contributing to this thread.

Thomas Walter