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Author Topic: Smooth Shading Mandelbrot plugin  (Read 10238 times)
Description: The dangers of increased bailouts and iterations
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panzerboy
Fractal Lover
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Posts: 242


« on: December 17, 2012, 05:17:46 AM »

http://sourceforge.net/projects/fxsmoothbrot

This fakes a true smooth shading by multiplying the true iteration count by 256 giving 255 in-between shades.
You need to have a high maximum iterations setting greater than 16383 or you'll just see a standard iteration banded Mandelbrot.
The smooth shading also benefits from a larger bailout, I recommend 4.
I had some interesting failures in programming this plugin so I've included 'Scalloped' and 'Partial Iteration' shading plus reversed versions,
 that is the colours sequence is reversed with the iteration band.

Programming this has been an interesting experience.
I copied Linas Vestas's algorithm, http://linas.org/art-gallery/escape/escape.html.
That has caused me some issues with lack of integer precision.
Increasing precision would slow down the calculation and that increased precision is only needed right at the very end of the calculation.
So when the calculation exceeds the bailout of 2 I increase the precision of the fixed point calculation by two words.
It should only be 1-2 more cycles after the bailout of 2 is exceeded that a bailout of 4 is exceeded.
Linas's algorithm then needs two more iterations to 'decrease the error term', so in total no more then 4 cycles at the increased precision.

Still runs pretty slow.
Part of that is the guessing won't avail you of much speedup, I've been turning it off.




* smoothbrot.jpg (217.24 KB, 1052x601 - viewed 621 times.)
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panzerboy
Fractal Lover
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Posts: 242


« Reply #1 on: December 23, 2012, 12:36:26 PM »

I've updated the Smooth Shading plugin.
It now does more fractal types.
Burning Ship
Celtic
Buffalo
Mandelbar Tricorn
Mandelbar Celtic
Perpendicular Mandelbrot
Perpendicular Burning Ship
Perpendicular Celtic
Perpendicular Buffalo.

I had a horrendous memory leakage bug with the Scalloped Shaded types once it hit the fixed precision calculations.
Not sure if that was in the previous version but it is fixed in this version.

Sourceforge seems to be taking a while to release the actual dlls, the source is available (not much use for most).
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panzerboy
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Posts: 242


« Reply #2 on: December 23, 2012, 07:49:14 PM »

Sourceforge still hasn't made the dll's available after 8 hours!
I've uploaded them to mediafirefire for the time being.

32 bit dll http://www.mediafire.com/?m86k3m1m6k39w8i
64 bit dll http://www.mediafire.com/?ota4css0feisqql
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simon.snake
Fractal Bachius
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Posts: 640


Experienced Fractal eXtreme plugin crasher!


simon.fez SimonSideBurns
« Reply #3 on: December 24, 2012, 01:39:42 PM »

Haven't seen any new plugins for some time, so glad you've taken the time to give it a go.

Just to say there's a plugin sub category in this forum that you could have put it in.

Will let you know if it works on my setup.
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panzerboy
Fractal Lover
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Posts: 242


« Reply #4 on: December 25, 2012, 12:42:13 AM »

Hi Simon.
I'm having intermittent problems with the fractals not loading properly.
Most frustrating, you spend hours on a render, save it and when you load it you see the base Mandelbrot and all your parameters are lost.
I'm investigating, but I'm not sure about this problem.
Best when saving a fractal to open an explorer window and double click on the .fx to load it in another instance of Fractal Extreme to check it saved okay.
Still trying to duplicate the problem.
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Dinkydau
Fractal Senior
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Posts: 1616



WWW
« Reply #5 on: February 17, 2013, 06:01:47 AM »

This is awesome! Unfortunately it's very heavy and makes my computer slow.




Hi Simon.
I'm having intermittent problems with the fractals not loading properly.
Most frustrating, you spend hours on a render, save it and when you load it you see the base Mandelbrot and all your parameters are lost.
I'm investigating, but I'm not sure about this problem.
Best when saving a fractal to open an explorer window and double click on the .fx to load it in another instance of Fractal Extreme to check it saved okay.
Still trying to duplicate the problem.

That's not an issue with your plugin. It happens with standard formulas as well. A solution is to save the fx file while using a low resolution. Maybe your plugins makes the files extra heavy so that the problem occurs more easily, and you need to decrease the resolution even more to prevent this problem.
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panzerboy
Fractal Lover
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Posts: 242


« Reply #6 on: February 20, 2013, 04:26:37 PM »

This is awesome! Unfortunately it's very heavy and makes my computer slow.
Its because of the synthetic iterations effectively cancelling the 'guessing'.
You image would have had a high guessed pixels percentage 70% or more?
With smooth shading about the only time you see much guessed pixels is in the interior (black areas).

Quote
That's not an issue with your plugin. It happens with standard formulas as well. A solution is to save the fx file while using a low resolution. Maybe your plugins makes the files extra heavy so that the problem occurs more easily, and you need to decrease the resolution even more to prevent this problem.
Thanks for that, I mustn't have been paying attention but I certainly have old ordinary mandelbrot .fx files that won't load.
The cutoff in size is between 106,300,622 bytes and 107,105,886, any file equal or above the latter size won't load.
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