Re: General bug - No out of bounds checking on 3D coordinates

[Daniel J S. <dan...@ie...>]

Ethan Merritt wrote:

>On Monday 05 July 2004 02:14 pm, you wrote:
>  
>
>>If it seems like it is the PDF utilities fault, then it should be fixed
>>there by someone else.
>>    
>>
>
>I think the chance of us changing the behaviour of a commercial
>product, even the free subset of a commercial product, is near
>zero.  Besides, it offends my sense of aesthetics to screw up the
>negative coordinates by wrapping around to huge positive numbers.
>Once that happens you can't even clip them properly.
>

I agree.

>>I notice that the 3D case for X11 clips off the bottom
>>three labels.  I notice that the PostScript output file shows the bottom
>>three.  I notice that inside the 'test.ps' file the bottom three labels
>>(the ones that X11 truncates) have negative y positions associated with
>>them.  (So, is PostScript expanding the screen to include everything?)
>>    
>>
>
>That is under the control of your viewer program.
>PostScript specifies a bounding box, but the viewer can ignore
>that if it chooses to.  In ghostview/gv you can toggle the this option
>from a menu somewhere.
>

Oh yeah, I forgot about that?

>> I notice that ps2pdf on 'test.ps' produces a 'test.pdf' that works fine
>>in Acroread.  (Does that imply that translating negative numbers for PDF
>>may not really pose a problem?) 
>>    
>>
>
>The problem is not in the PDF file format itself, it's in the libpdf
>library routines.  ps2pdf doesn't use libpdf.
>
>  
>
>>I notice in both X11 and PostScript 
>>that the labels at the very bottom and very top do not have red lines
>>drawn to them.  Is gnuplot treating the "extent" of the plot to the
>>portion inside the labels, and anything beyond that is clipped?
>>    
>>
>
>Wasn't it you who said just upthread that you thought clipping
>should be left to the individual drivers?  They don't all do it the same
>way (or do it at all, in some cases).  If you want a consistent clipping
>policy then we would have to move it into the core gnuplot routines
>rather than leaving it to the terminal drivers and associated support
>libraries.
>

Yes, but (the politician in me says) I think there are two different 
issues.  In one case you have the consistency of how gnuplot constructs 
the plot, what that should be I'm not completely sure.  At the driver 
level we are talking a sanity check, and that is where I'm saying 
map3d_xy() shouldn't be doing that.

As for the particular method, I don't know.  Maybe if the plot borders 
are drawn on the plot, then everything should be clipped at the borders. 
 If the borders are not drawn, maybe everything should be clipped at the 
viewport (or not at all).  An option?

Dan