[Radiance-dev] proposal: switching executables from within rad?

[Lars O. Grobe]

Hi folks,

this is something that was first proposed by Carsten in his Radzilla 
documentation:

"'radz' has one additonal option: you can set the name of the executable 
to call. This is very helpful in case you have several RADIANCE versions 
in parallel. The option name is '-x', example:

$> radz -x rzvu -o x11 test.oct /or/
$> radz -x rpict_xyz25_b test.oct /or whatever/...

If -x is not set, the RADZILLA execs will be run (either 'rzpict' or 
'rzvu', dependent on the additional setting of -o x11)."

Obviously noone ever cared about it later. Still, I think it may be 
useful, so I try to describe...

Radzilla provides a radz-tool, compareable to rad, which controls the 
rendering and filtering processes. As Radzilla heavily depends on 
Radiance, Carsten spent some time on integrating both, and one thing he 
did was adding an x-option to radz, which specifies the renderer to use.

E.g. radz -x rpict will use rpict, radz -x rzpict would run rzpict, radz 
-x rvu would open the preview.

I think this is a very elegant solution, even better then using the -o 
devices, as it allows e.g. combining binaries from different releases, 
or alternative projects such as radzilla, or patched tools, and still 
control all by rad without a need of symlinks, PATHs and so on.

While I like the solution in Radzilla, I guess it would become even 
better if these options would not be set as a command line option, but 
either as a optional variable in the rif-file or as an environment 
variable. I would also propose this to be a general mechanism for all 
tools that are called from inside rad. So my proposal would add optional 
xrpict, xmkillum, xoconv, xrvu, ... variables, which by default would be 
the radiance distribution's (that rad came witch) binaries, overwritten 
by environment variables, overridden by rif-file variables.

So... I could use all filters e.g. from the most recent radiance 
release, and combine with a pmap-extended rpict. Or I could run my 
renderings using radiance's rad, and by setting  an environment variable 
xrpict=rzpict could re-run all using rzpict to compare.

The reason I would like to have this is that I am currently processing 
the same scene, views using radiance classic, and older radiance+pmap 
and radzilla. I could go with scripts setting PATHs, doing symlinks and 
all that - but this is errorprone and not very transparent. I also think 
that these variables would be both helpful for folks having different 
radiance-releases installed (but only on is called from the PATH) or for 
debugging and development. So what do you think, would this be a 
reasonable addition to the already crowded rad-world of options and 
variables?

CU Lars.