[Radiance-general] my real question

[Peter Apian-Bennewitz]

Hi Qing,
 
> For this moment, I think I should tell you my real situation. From the requirement
> of our project, I could not use the Radiance in the form of command line and I
> must change some codes to form our own APIs (making use of static library).

So, I guess you're developing an interactive, graphical program that
displays an image that uses values calculated by some routines of
Radiance. Which would be most easily done using one of
fork&exec/system/popen on Posix (e.g. Linux/UNIX) systems, Windows may
have similar means of communicating with external programs. But you
said, you can't do 'system' calls. Does that mean you can't read from an
externally started program ?

> I couldn't use system calls. We can get the required image using API altered from
> "rpict", 

What do you mean by "API altered from rpict" ? Using the rendering
routines from rtrace/rpict would be feasible, but it doesn't explain why
you have trouble with rtrace output.

and then our real problem is to specify a region (or even a single
pixel)
> on the image plane to get the radiance value and the picture of that region. In my
> opinion, "rpict" can specify the exact position on an image plane.
?? 

> So, I use the changed "rtrace" to render the region to obtain their radiance values (r, g, b)
> and then I want to transform them into a suitable file form to obtain the picture.
> I know I can get the answer through looking into the source codes, but I do not
> have so much time for that. I have tried the method Dr. Peter told me. However,
> that method sometimes works well and sometimes not.
?? It fails if and how ?

> Now, I want to take advantage the Radiance picture directly.
??

> opinion, what is the better solution for my problem?
I'm still not quite sure I understand what you problem is-

-Peter
-- 
 pab-opto, Freiburg, Germany, www.pab-opto.de