[GRASS-dev] nviz export PPM

[Glynn Clements]

Brad Douglas wrote:

> The export to high-resolution PPM in nviz is broken.

AFAICT, it has *always* been broken, in the sense that getting it to
work has always involved an element of luck.

> Exported images
> either alternate between good and garbage pieces, or it gets to a point
> and the rest of the image is garbage.  I currently have no repository to
> post data and images, but I can email to anyone who wants to take a
> look.
> 
> I also noticed my PBUFFERS and PIXBUF changes were backed out again.
> The way it is configured now will have the least amount of success for
> the majority of users.

OTOH, the current setup results in the code getting a lot more testing
than would be the case if users had to enable pBuffers/Pixmaps
manually. As the behaviour is likely to vary significantly between
systems, depending upon the graphics hardware, drivers, and X version,
this isn't something that can be solved "in house"; we *need* user
feedback on this.

> Video acceleration should be an option, not the rule.

Use of pBuffers/Pixmaps isn't about "acceleration", it's about
"off-screen" rendering. The image is rendered for the purpose of being
saved to a file, rather than displayed to the user.

The option to render directly to the window is intended as a fall-back
for OpenGL implementations which don't provide any other rendering
targets, and has enough problems of its own. If pBuffers/Pixmaps work
on a given system, they should be more reliable than rendering to the
window.

-- 
Glynn Clements <glynn at gclements.plus.com>