On 28/08/2012 7:49 AM, Stephane Chantepie wrote:
thanks for the reply
I am sorry but I do not have any skills in C++
Nevertheless, I found a solution to my problem... By using another package
"misc3d" and more precisely the association of the two
functions drawScene.rgl and surfaceTriangles
drawScene.rgl(surfaceTriangles(x,y,z,color="gray",smooth=1))
The idea behind this trick is to transform the matrix in triangle surfaces
before to plot them.
I hope this could help someone else
Thanks, I didn't know about those functions.
Duncan Murdoch
cheers
2012/8/27 Duncan Murdoch <murdoch.dun...@gmail.com>
> On 27/08/2012 1:47 PM, Stephane Chantepie wrote:
>
>> Dear all,
>>
>> I have tried to plot a triangular matrix with the function persp3d(rgl).
>>
>> for example
>>
>> z=rbind(c(1,NA,NA,NA),c(5,3,**NA,NA),c(4,2,9,NA),c(8,6,5,11)**)
>> x=1:4
>> y=1:4
>> persp3d(x,y,z,color="gray")
>>
>> The two extreme points are not plotted (value=1 and value=10). It seems
>> because the half of the matrix have 'NA' and perp3d need planar
>> quadrilateral face. So I decided to use the function triangle3d to
>> integrate these points into the scene.
>>
>> So, for the first point I did :
>>
>> triangles3d(x=c(1,2,2),y=c(1,**1,2),z=c(1,5,3)) and it worked
>>
>> But a problem remains because the light movment on this triangle looks
>> independant and I did not find how to solve this issue.
>>
>> How can I prefectly integrate this triangle into the scene?
>>
>
> You need to set the normals at the vertices that are shared with the
> persp3d vertices. rgl internally averages the normals to the pieces making
> up each facet; you don't have enough access to the internals to do that.
> (You'd want to change the normal on the surface, as well, because your
> triangles should participate in the averaging.)
>
> But you could set the normals to the new triangle to match the normal to
> the one it joins to, and get something that looks sort of okay. It's not
> going to be a simple calculation: you need to figure out the coordinates
> of the edges joining at those vertices, take a cross product, and use that.
> See ?rgl.primitive for how to send the normals to points3d; I think the
> normals need to be length 1, but that may be forced internally.
>
> If you were really ambitious, you could take a look at the C++ code that
> draws the surface, and contribute code to smooth the edge properly; I think
> it would be an improvement over the current behaviour, but it is tedious to
> write.
>
> Duncan Murdoch
>
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