Old 9th December 2017, 19:21   #1
chrisjj
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Mystery noise in uv

Is there a Milkdrop 2 preset author who could try the attached test preset for me and post a screenshot of the result?

It's a blank preset with this one-line warp shader:

ret = (uv.y*5000)%2 < 1;

in a window 416 pixels high (as shown by the monitor at top right).

Here, the output id this:



(or a variant, depending on window height) continually changing, not a static pattern of unbroken horizontal lines as expected.
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Old 9th December 2017, 19:24   #2
chrisjj
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Oops - attachment lost.

Reattaching here.
Attached Files
File Type: milk CJ test lines.milk (4.8 KB, 35 views)
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Old 17th December 2017, 14:11   #3
Nitorami
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It depends a lot on the actual screensize, as you are getting moiré patterns.
To avoid this, don't use "5000" but the actual screen height in pixels like this:

float k= 15;
ret = (uv.y*texsize.y*k)%2 < 1;

You can adjust the appearance by setting the value of k. It makes rather a difference whether it is a multiple of 2 or not.

Note - the pattern is actually moving because of the line "warp = 0.01000" in the milk file. Unless you explicitly overwrite these distortion parameters (e.g. rot, warp, zoop, sx,sy,dx,dy) in your code (in the per frame or per vertex section), milkdrop takes the values from the .milk file. So you'll see a distortion effect but no corresponding code, which can be a bit confusing.
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Old 17th December 2017, 14:26   #4
chrisjj
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[QUOTE=Nitorami;3146604]It depends a lot on the actual screensize[quote]

I know. Hence my "(or a variant, depending on window height)".

[QUOTE=Nitorami;3146604]It makes rather a difference whether it is a multiple of 2 or not./QUOTE]

Sure does

And I'm guessing that's not the only thing that makes a difference. E.g. GPU model.

I'd be interested in seeing your screenshot for comparison.
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Old 17th December 2017, 15:17   #5
Nitorami
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chrisjj

I have checked with nvidia and an AMD iGPU, there is no difference. I would be surprised if there was any, with such simple code. With the mods as suggested, you'll get a definitive behaviour which does not depend on screen size neither on GPU.

With your orginal code, the appearance is very sensitive on screen size. Sometimes I get a picture similar as yours, sometimes the fine lines as you seem to expect. There is not much point in making a screenshot, it would be rather random, and I do not know how to set a height of exactly 416 pixels.
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Old 17th December 2017, 18:19   #6
chrisjj
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Quote:
Originally Posted by Nitorami View Post
With the mods as suggested, you'll get a definitive behaviour which does not depend on screen size neither on GPU.
The mods as selected just reduce the sensitivity of the test.

Quote:
Originally Posted by Nitorami View Post
With your orginal code, the appearance is very sensitive on screen size.
Same here. Which is why I specified screen size.

Quote:
Originally Posted by Nitorami View Post
There is not much point in making a screenshot, it would be rather random
Not if you set the screen height, I suspect.

Quote:
Originally Posted by Nitorami View Post
I do not know how to set a height of exactly 416 pixels.
1) Press N to engage the monitor in top left
2) Resize the window until the monitor says 416.0000
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Old 17th December 2017, 19:18   #7
Nitorami
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416 lines
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