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[Seg3D] Re: Re: Re: Re: New Spline Tool


Chronological Thread 
  • From: "David Brayford" <dbrayford@sci.utah.edu>
  • To: seg3d@sci.utah.edu
  • Subject: [Seg3D] Re: Re: Re: Re: New Spline Tool
  • Date: Fri, 16 Oct 2009 11:17:00 -0600
You could just convert the spline into a series of points and connect the points using GL_LINES

David

On Fri, 16 Oct 2009 18:00:03 +0100
 Ramón Casero Cañas <ramon.casero@comlab.ox.ac.uk> wrote:
Michael Callahan wrote:

Eventually, I would like to replace the polygon lines by a spline curve. Does anybody have any suggestions on how to do this? I know almost nothing about OpenGL.

You divide the spline up into line segments and draw those.

Hi Michael,

Thanks for the advice.

I have seen that it's possible to draw a spline as such in OpenGL using glMap1f() and glEvalCoord1f() [1], but in any case I would need to compute the spline explicitly also if I want to do the "contour" segmentation.

I suppose that computing the spline first (typically as a periodic cubic spline), and then converting the seeds to control points of Bézier basis functions for OpenGL is too much hassle, and probably prone to error.

So I'll follow your advice, compute the spline coefficients, then sample it to get small line segments, and plot those.

[1] http://glprogramming.com/red/chapter12.html

Best regards,

Ramon.

--
Ramón Casero Cañas, DPhil

Computational Biology, Computing Laboratory
University of Oxford
Wolfson Building, Parks Rd
Oxford OX1 3QD

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