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I've written a Cycles node tree to convert rectangular (X,Y) to polar coordinates (R,theta) as the basis for a procedural texture with radial symmetry.

However, there is a seam in the texture where theta jumps in value (-pi -> pi or 0 -> 2pi).

What are some of the techniques for eliminating this seam? I have found one method that uses a blended overlap region. Are there others?

astrogeek
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    Have a look at this: http://blender.stackexchange.com/a/45169/7777 – Jaroslav Jerryno Novotny Jan 27 '16 at 13:26
  • That's useful for textures with regularity. Thank you for including the details of the node groups for the cylindrical and spherical projections. I will compare them to the node groups I created.

    I plan to use Noise, Voronoi, or Musgrave textures that do not repeat like the chevron in your solution. I expect the discontinuity at -pi (or 2pi) will be visible.

     – astrogeek Jan 27 '16 at 16:28
  • Yes, when the texture is not tiled you will have a seam. – Jaroslav Jerryno Novotny Jan 27 '16 at 17:28
  • I am curious as if you have found a solution to this issue... – Eranekao Mar 13 '16 at 04:01
  • @astrogeek More specifically, would you mind showing us how you achieved the blended overlap region or linking the solution you found? I'm having the same issue. – Eranekao Mar 16 '16 at 21:58
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    @VilkoL I haven't gotten back to this issue yet. I'm currently hiding the seam by using a texture with a really large scale (i.e. small-scale features) so the seam is largely mixed in among the many variations in the texture.

    I found this wonderful page http://paulbourke.net/texture_colour/edgeblend/ and intended to use his algorithm. The middle-to-last part of the page gets into the details.

     – astrogeek Mar 18 '16 at 01:24
  • Something like this may help : https://blender.stackexchange.com/a/119564/29586 – Rich Sedman Aug 25 '20 at 21:08
  • @ Rich, that page poses a great solution. Thanks for the heads-up so many years after my original post. – astrogeek Aug 26 '20 at 22:10

1 Answers1

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Sine and cosine pair to bend an axis into a loop.

I'm using a sphere to represent to polar coordinates but the math applies regardless.

This will use up 2 axes of your procedural texture for the Theta component.

sphere with seamless tiling at its UV sphere

Important to have the theta properly in radians. here it's done by, mutiplying it by 2π.

sybog64
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