[gts-general] Re: Gts-general digest, Vol 1 #513 - 2 msgs

[Korcan K. <k.k...@tu...>]

Hello Mike,

thank you very much for your help. I didn't understand one point: While I am 
calling the gts_surface_foreach_face function to call a function that uses
gts_segment_triangle_intersection ; how do I give the triangle? The 
fuction  "gts_segment_triangle_intersection" needs a specific triangle to 
operate. This is again the same problem with the vertices..
Again thanks for answering to my questions.

Korcan

Zitat von gts...@li...:

> Message: 2
> From: "Mike Loehr" <mic...@ad...>
> To: <gts...@li...>
> Subject: RE: [gts-general] a vertex of a surface
> Date: Fri, 21 Jan 2005 07:54:16 -0500
> Reply-To: gts...@li...
> 
> Greetings Korcan;
> 
> The vertices in a GTS surface are not indexed.  To get a particular vertex
> you must increment through the surface to find your desired vertex.
> 
> You will need to have a co-ordinate value (not necessarily the exact
> vertex)
> that is outside of the surface. Possibly the viewpoint, camera, or light
> location if you are rendering.
> 
> Create new vertexes for the center of the sphere and your point using
> gts_vertex_new.
> 
> Construct a segment between the center of the sphere and your point using
> gts_segment_new.
> 
> Use gts_surface_foreach_face to call a function that uses
> gts_segment_triangle_intersection to determine if a given triangle is
> intersected by the segment and is to be selected.
> 
> Then use gts_triangle_vertices to extract the triangle vertices from the
> selected triangle and determine which is the desired vertex from the
> triangle (using your own function) to give to the curvature function.
> 
> AFAIK the gts_point_locate would only work for an open surface.  Your
> sphere
> would have two triangles in the planar projection that enclosed the point.
> 
> There is probably a more elegant solution using bounding boxes or trees or
> something else, but brute force works.
> 
> Mike
> 
> -----Original Message-----
> From: gts...@li...
> [mailto:gts...@li...]On Behalf Of Korcan
> Kurtoglu
> Sent: Friday, January 21, 2005 5:01 AM
> To: gts...@li...
> Subject: [gts-general] a vertex of a surface
> 
> 
> Hello,
> 
> i have a very basic question. How can I get a vertex of a surface that I
> have
> created?
> I want to copmpute the gaussian curvature on this vertex. How can I give
> the
> vertex that I want to the function? I mean for example I have a sphere that
> I
> have created. How can I define the program a specific vertex that I want ?
> Thanks.
> 
> Korcan
> 
> 
> 
> 
> 
> 
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