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[Solution at bottom of question]

I'm trying to create a shader to draw dots in a wavy pattern. I have the dots, and I have the waves, but I'm not sure how to combine the two.

I create the dots by adding together 2 wave textures that are 90° apart from each other, and use a Less Than node to draw each dot with a hard border. (Fun fact -- if you rotate the overall dot pattern by 90° you can switch between staggered and non-staggered dots.) This results in a grid of dots.

The "wavy waves" pattern is a combination of two wave textures. One base wave with another wave being added to the X-coordinate of the base wave to create the variation.

Every time I've tried to combine the dots with the waves doesn't work out... the waves always end up squishing or stretching the dots. I don't want that -- I want to keep the circular dots, and only adjust their placement to match the wave pattern.

Any advice? Intended end-result below.

.

Shader nodes to draw plain dots: draw plain dots

Resulting plain dots plain dots result

Shader nodes to draw wavy waves: draw wavy waves

Resulting wavy waves: wavy waves result

End goal:

enter image description here

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Solution

(thanks to @RobinBetts below)

Using Robin's clever method of UV tiling, I made a small change to achieve just what I wanted. (note - you need 2.81 to open Robin's .blend file)

I wanted to be able to adjust the spacing of the dots in the X and Y, which I think is the next step after Robin's answer. To do this, I changed the Fraction node into a Modulo node, which lets you adjust how quickly the UV space is repeated. Note that the modulo coeff in the X direction must always be a positive integer to keep the correct dot shape. The modulo coeff in the Y direction can be any positive number. And that's it. Adjusting the Scale, Freq, and Amplitude does all the rest.

added modulo node

enter image description here

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    $\begingroup$ Yay! Much simpler than I thought. If you posted that as an answer, we could UV it... $\endgroup$ – Robin Betts Dec 11 '19 at 18:26
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    $\begingroup$ Here are a couple of tweaks you might consider to make your solution a bit more general / goofproof. $\endgroup$ – Robin Betts Dec 11 '19 at 19:07
  • $\begingroup$ Very cool. The sawtooth mod is new to me. Nice additions. I had modified my object UVs to make up for the negative quadrants but that's kind of hacky -- your solution is more robust. $\endgroup$ – natedogg Dec 11 '19 at 19:23
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    $\begingroup$ 'Sawtooth Mod' is only my name for it.. it's the way GLSL implements mod().. different from Blender's, for negative numbers. I'll replace the .blend in my answer with your solution. $\endgroup$ – Robin Betts Dec 11 '19 at 19:31
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This tree divides the UV space into XY cells, and samples the sine of X at every cell to stagger the position of the Y cells.

enter image description here

This results in a modified UV space which looks like this: (X->R, Y->G, 0 at the center of each cell)

enter image description here

This space can be used to tile any UV-dependent texture in a sine-wave pattern.

In this case, we use the output vector as the 'Vector' input of a procedural dot:

enter image description here

With this sort of result:

enter image description here

It's actually quite tricky to adjust the frequency and amplitude so the cells sample the sine wave at the right rate to maintain the 'wavy' look, but I don't think that can be constrained to make it easier.. unless we fixed it to make every other row black, or something, so the right dots are associated with the right dots, perceptually. We could tweak it to do that, or something like it, if you like.

EDIT: @natedogg has improved the answer, to make it easier to see the pattern. (See OP) The attached .blend includes the improvement.

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  • $\begingroup$ This looks great! Thanks, I wouldn't have thought of this method. I see what you mean about the sensitivity to adjustments. How would you enable controlled dot spacing in the X and Y directions? E.g. the same wave pattern but with different dot spacing in the Y? $\endgroup$ – natedogg Dec 11 '19 at 17:48
  • $\begingroup$ @natedogg ..same thought occurred to me.. actually quite a dig-up, but I'll have a go... just checking which way you wanted to go. $\endgroup$ – Robin Betts Dec 11 '19 at 17:51
  • $\begingroup$ I figured it out -- changing the Fraction node to a Modulo node enables adjusting in X and Y. As long as you mod against integers (in the X) you'll get a nice complete pattern. Modding in the Y is not constrained only to ints, decimals are OK. $\endgroup$ – natedogg Dec 11 '19 at 17:54
  • $\begingroup$ @natedogg.. scaling OK? .. also beware of modding negative numbers ... Go ahead and answer your own question with your version.. I'd like to see it. $\endgroup$ – Robin Betts Dec 11 '19 at 17:57

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