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Jurgen

Equations - a general comprehensive overview?

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Hello there,

 

in the tutorials equations are mentioned a few times, like in the Macros videos. But there is no general overview of the functions that I am aware of - for instance, relative to noise the video mentions that there are 4 different noise generators but I didn't find specific explanations as to possibilities using equations.

 

Is there anything? I'd be glad to go through it...

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Plus to that. When I was writing my resize macros I had trouble finding the right information. I found it under Field Entries! I found that the only circumstance where Equations work reliably is in Filter > Distort > Equations. In the Transform panel, you can appy an equation in the fields, but the resulting value is then fixed. This means that if you enter an Equation in the Width field, then if you wish to refer to the Width in the Height field, it uses the new width, not the original width!

I aim to have a little project to explore the Equations faciity in Affinity and report back in the Tutorials forum.

Perhaps the Mods could confirm that Equations are on their to-do list for Transform and for Document > Resize.

 


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In the tutorial "Macros: Equations" there is mention of different noise algorithms available in the equations - I would be glad if these (and everything else possible with equations) could be subject to a tutorial or online paper sometime. :-)

 

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It is a complete list, but it is lacking in how to  to use them effectively. I have been focussing on the mathematical expressions at the end, for which it says: For general use throughout the user interface! As I mentioned above, these seem to work only in the Distort > Equations filter.

My first exploration of these has been the sine function sin(x). So far, I have got it to work, but with unexpected scaling effects. I will be reporting further on this.

BTW, I tried the Noise function, and it appears to have no effect whatsoever! Perhaps it would help if there were some documentation.


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8 hours ago, Jurgen said:

... for instance, relative to noise the video mentions that there are 4 different noise generators but I didn't find specific explanations as to possibilities using equations.

Is it just something I am doing wrong or has anyone else noticed that the Noise2 expression always is displayed in red & does not work in Filters > Distort > Expressions, while the other 3 do?

 

11 minutes ago, John Rostron said:

BTW, I tried the Noise function, and it appears to have no effect whatsoever!

Assuming there are pixels present in the targeted layer, all but Noise2 have some effect when I try them, although the results are hard for me to predict. Some (not particularly useful) expressions to try:

 

x= x*noise(w,y)

y= y*noise(h,x)

 

x= x

y= y*noise(y*a)


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Try this one. (see image)
Use the slider to adjust the effect from 0 - 100

@R C-R

noise2 does not appear to work but more surprisingly noise5, noise6, and noise7 all work

 

 

noise.jpg


Due to the fact that Boris Johnson is now our Prime Minister, punctuation, spelling and grammar will never be worried about ever again.  We now have far bigger problems to be worried about.

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1 minute ago, carl123 said:

noise2 does not appear to work but more surprisingly noise5, noise6, and noise7 all work

Because I am too lazy to find out for myself, do Noise5, etc. do anything different visually from (for example) Noise1 or Noise4?


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5 minutes ago, R C-R said:

Because I am too lazy to find out for myself, do Noise5, etc. do anything different visually from (for example) Noise1 or Noise4?

There is no Noise1 and I don't cater for lazy, you need to do your own testing :)


Due to the fact that Boris Johnson is now our Prime Minister, punctuation, spelling and grammar will never be worried about ever again.  We now have far bigger problems to be worried about.

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12 minutes ago, carl123 said:

There is no Noise1 and I don't cater for lazy, you need to do your own testing :)

One of the reasons I asked (besides being lazy, of course) is Noise7 does not work for me -- like with Noise2, it shows up in red & has no effect. A related reason is I do not know if this might have anything to do with the other terms in an expression you have tested but I have not.


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15 minutes ago, R C-R said:

One of the reasons I asked (besides being lazy, of course) is Noise7 does not work for me

Brilliant, you see what happens when you test for yourself, you discover an error in my previous post.  Now you only need to test noise5 and noise6 to see what they do differently (if anything?)


Due to the fact that Boris Johnson is now our Prime Minister, punctuation, spelling and grammar will never be worried about ever again.  We now have far bigger problems to be worried about.

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@carl123, this is an interesting artistic effect. It should be worth while exploring the possibilities and documenting them in a Tutorial.

2 hours ago, John Rostron said:

My first exploration of these has been the sine function sin(x). So far, I have got it to work, but with unexpected scaling effects. I will be reporting further on this.

I have found that the unexpected scaling effect is because Equations expects the parameter in degrees, and I was using radians! Again, there is no documentation on this. I will post a  couple of images shortly.


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Here are a couple of applications of SIn to the Severn Bridge in the Mist:

The first is the original image.

The second has the y-coordinate set as y+30*sin(2*360*x/w)

The third has the y-coordinate set as y+20*sin(9*360*y/h)

SevernBridgeMist800.jpg

SevernBridgeMist800Sin1.jpg

SevernBridgeMist800Sin2.jpg


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34 minutes ago, carl123 said:

Now you only need to test noise5 and noise6 to see what they do differently (if anything?)

But even if I take considerable time to do that, I can't be sure if the results are different enough to notice. As it is, even for some of the simpler expressions there are no noticeable differences when I change from one of the noise expressions to another one, or the differences only are apparent on some document sizes and/or ones with different pixel content.

 

As John said, the expressions documentation is inadequate, particularly for the distortion filters. That should be obvious, if from nothing else than what you have discovered about higher dimension noise expressions or what I did about Noise2 not working at all.


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I have posted a more extensive tutorial on using trig functions in the Tutorials section. So far I only include using sines, but I will add more.

John


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