Add hypocycloid plugin about lazpaint HOT 13 CLOSED

Thanks for your time :)

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I've added the hypocycloid in the render menu. I've refactored and encapsulated things so that this can be reused to do another rendering.

The principle is to create or update the vector original with the shape. The parameters are stored in the layer registry so that they can be retrieved when rendering again.

I invite you to have a look at the following commit: 5121b62

Many files are changed, this is mainly due to adding the hypocycloid in the menus. The main part is in uhypocycloid.pas.

I would appreciate your feedback on this implementation, especially any suggestions for improvement or if you notice any issues. Thank you in advance!

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Hi, I've tested the plugin and works fine. Thanks for this addition :)

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I've tried adding the decimals, but I just get a rounded corner. Seems that the code has changed a bit more than I think...
Anyways I understand that is not a normal fillable shape with decimals, so it's ok like it is now.
Let's go with the other plugins!
I've created a thread in BGRABitmap forum:
https://forum.lazarus.freepascal.org/index.php/topic,64708.msg492242/topicseen.html

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Hi, here is the working code for Pascal
https://github.com/bgrabitmap/demo/blob/master/hypocycloid/umain.pas

I've ported it from JavaScript
https://codepen.io/enxaneta/pen/WQPdvV

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Hi Lainz!

So as we have discussed, there is way to implement it without involving to much more coding. The principle would be to have a filter window that would replace the current layer by a vector layer containing the drawing and save information in the layer about the parameters to produce the shape. This way, the filter window would be able to retrieve the information later and the user could update the shape by adjusting the parameters. Saving information in a layer is already implemented and used for example by Python scripts.

I will work on the basics to make this.

Regards

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Thankyou, I will review it on next Sunday. Unfortunatelly I'm having some health problems and I need to cover the days I don't work.

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I understand. This can wait. Take care and good luck

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Maybe can be added decimal places without compromising speed...
Like a trackbar with just + 0.1.. 0.9 to limit the complexity but at the same time giving more options.
Just an idea.

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The problem though is then to determine when it stops looping. One way to know for sure when it ends looping is to have 2 numbers: a numerator and a denominator (up to 3). The denominator is the number of turns. For example 5/2 will make a star shape with 5 corners in 2 turns. One need to simplify the fraction, as 6/2 will in fact be the same as 3.

You can give it a try if you like by modifying the MakeHypocycloid function.

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Ok I will try
The idea was not a fraction but a simple decimal place.
Like I choose 6 in the spinedit. Then in a slider I choose from 0 to 9. For example if I choose 3 it becomes 3.6 number. These decimal places are computed in more or less time but always computed. And gives nice shapes.

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I see the appeal of decimal values for intricate patterns. However, fractions like 3.1 might lead to numerous turns and more vertices, affecting editability of the generated shape by users.

Using denominators of 2 or 3 ensures predictability of the loop. With decimals, one cannot express a precise fraction like 7/3 that nicely loops after 3 turn. I invite you to try to approximate 7/3 = 6.333 and see how it goes.

It is a great idea to open this thread on the forum, it is likely to attract people's attention on a more concrete way of improving LazPaint.

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Ok yes you are way better in math than me. So if you think fractions are better then we need to go that way.
Thank you. Yes I've seen many drawings that can be added as plug in in the forum. But I can't remember where so for that I opened the thread.

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