[R] "Over-coloring" facets on persp() plot

[Duncan Murdoch]

On 23/11/2009 8:55 AM, Marc Chiarini (Tufts) wrote:
> Thanks Duncan (and David).  I couldn't get back to my computer until 
> today.  I understand it pretty well now and I'm able to get what I need.
> 
> On a side note, I have had a hard time getting rgl to work.  For the 
> moment, I have to compile without libpng and ftfonts, and when I load 
> the package I get an error related to OpenGL (from memory, something 
> like "no GLX extension found").  I'll write more as soon as I'm able.


You likely need to install OpenGL support on your system.  (It might be 
in MesaGL.)

Duncan Murdoch

> Regards,
> Marc Chiarini
> 
> Duncan Murdoch wrote:
>> On 22/11/2009 1:07 AM, Marc Chiarini (Tufts) wrote:
>>> Dear R Community:
>>>
>>> Recently, I have managed to plot some really useful graphs of my 
>>> research data using persp().  I have even figured out how to overplot 
>>> rectangular regions (corresponding to submatrices) with a different 
>>> color.  This is accomplished by using par(new=T).  I am now searching 
>>> for a way to "highlight" a set of (possibly non-contiguous) facets 
>>> with a specific color, e.g., the facet between each set of four 
>>> points whose values are all above a certain threshold.  An example 
>>> would be coloring the raised corners of the classic sombrero (found 
>>> in example(persp)) differently from the rest of the sombrero.  I feel 
>>> like the last example in persp() is pointing me in the right 
>>> direction, but I'm not quite getting it.  Any help is much appreciated.
>> Think of the facets as an nx-1 by ny-1 matrix.  Pass the col arg by 
>> creating a matrix of this shape.  (A vector version of the data in the 
>> matrix would also be good enough.)
>>
>> If you pass something shorter, it will be recycled to that length.
>>
>> You could also use persp3d from the rgl package, but an important 
>> difference is that it colours all nx by ny vertices, and interpolates 
>> colours on the facets.  So you can't use the same colour matrix as in 
>> persp.
>>
>> Duncan Murdoch
>>
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>>
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