Hi Axel,

Because I use the -S option to rpict when rpiece calls it, I can't change the 
output resolution of the tiles -- they all have to match up exactly.

I thought about adding a warning, but I'm muddled as to when to warn the user 
and when not to.  Oftentimes, a particular view demands that one or the other 
image side be reduced to fit the desired pixel aspect ratio (1.0 for square 
pixels by default).  I don't think the user wants to be warned about this 
standard rpict-like behavior.  You only want to know when the dimensions 
produced by rpiece will differ from those that would have been produced by 
calling rpict directly, right?

-Greg

> From: Axel Jacobs <[email protected]>
> Date: January 19, 2012 7:06:52 AM PST
> 
> Dear list,
> 
> I appreciate the irony: with the 'no light sources' warning removed
> from rpict, I would like to request a new warning, this time for
> rpiece.
> 
> vwrays and rpict calculate the overall image dimensions from the -v*
> parameters and the -x and -y image dimensions. When rpict is run
> through rpiece, the image is split up into tiles, each of which is
> rendered in a separate thread. The tiles are then pcomposed into the
> final image. The width of the final image is xdim = tilex * xdiv,
> where tilex is computed by rpiece. Since tilex needs to be an int, it
> is actually calculated as floor(xdim / xdiv). If the requested xdim is
> not divisible by xdiv, xdim of an image generated by rpiece will be
> smaller than xdim of an image with exactly the same -v*, -x and -y
> generated by rpict. Same goes for the height of of the image...
> 
> I have stumbled across this a few times now. Admittedly, I tend to use
> rpictmt from 
> http://www.bakharev.org/index.php?option=com_content&task=view&id=23&Itemid=38,
> which is a convenient wrapper around rpiece, although it makes no
> difference to the problem at hand.
> 
> So my feature request is actually a warning request: Could rpiece
> output a warning like:
> "warning: requested image size of xdim x ydim reduced to xdim1 x
> ydim1" to stderr.
> It would be even cooler if the last tile within a row had its tilex
> adjusted so that the final image comes out exacly like an rpict one
> (ditto for tiley for all tiles within the last row), but this is
> probably more difficult to implement, otherwise I guess you would have
> done it already.
> 
> Many thanks
> 
> Axel

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