Gradient editor design for a fractal explorer program

[zenzero-2001]

Hi

I wondered if I could garner opinions about the design of a gradient editor for use in a fractal explorer.

For my fractal explorer "Fractalscope" (the first version of which, will hopefully be released before the next ice age) I have programmed a gradient editor similar to that used by Ultra Fractal. The gradient editor in Fractalscope / Ultra Fractal has control point nodes defining a colour curve, there is a curve each for red, green and blue. A node has a red, green and blue value but only one value for defining its position in the gradient. Therefore, in the editor a node in one colour (red, green or blue) is linked to the other two corresponding nodes. This means that each colour (or shade widget as I have called it in my program) has the same number of nodes as the other two widgets and that moving a node horizontally in one widget also moves the corresponding nodes horizontally in the other two widgets.

From a user's point of view, I was wondering if this was a good design or whether it would be easier to have the three colours independent of each other? I.e. each colour having a position independent of the other two. Having the three colours act independently would mean one could define and move nodes without them affecting the other two colours, it would also mean one would need to place less nodes to define curves like a staggered saw-tooth etc.

Initially, I found the linked node style gradient editor less confusing and easier to grasp / begin with (intuitive is the word I am looking for). But now, I think maybe it is more cumbersome than having the nodes act independently. What do you think?

I would greatly appreciate any comments or opinions from a user's perspective, thanks very much.

zenzero-2001

[youhn]

I'll try to describe the good&bad of some different fractal palette tools of fractal software I've been using. I'm still waiting for someone to implement a combination of the infinite waves of Kalles Fraktaler, plus the normal palette options of Kalles, plus the layer modes (blending modes) from the Gimp (see http://docs.gimp.org/2.8/en/gimp-concepts-layer-modes.html ).


Xaos
Randomized palettes using 4 different algorithms. You can specify a seed value, algorithm type and palette shift for a deterministic workflow. But I found it much easier to just let the randomizer do it's work and then color-cycle around for fine-tuning. This works remarkably easy, specially since the color cycling works fast as hell. Only there is no option to fine tune the palette itself.

Source code available from http://xaos.sourceforge.net/index.php


Gnofract4D
The palette editor uses color gradients. Each gradient has a begin color and an ending color. The gradient can be splitted manually in order to create more colors. Very easy to use, not so flexible. Advanced things like adding color stripes at regulary intervals or even waves of color is not possible.

Source code available from http://gnofract4d.sourceforge.net/


MDZ
Guided randomization. I thought this one is actually very cool. You can only adjust a few basic things, but it seems like an advanced editor anyway. Maybe the only one in it's sort. It works with waves of color and can blend many palettes. For each R G B color channel you find 2 sliders. One for the frequency (Bands) and one for level of blending (Strength). At full strength, you get a totally new palette every time. If you have low strength and randomize many times ... you end up with a grey palette. After playing with these semi-random bands of color, you can add stripes at regular intervals. But the stripes actually use the color waves, it's hard to explain. You really should try it! Works very well with the color cycling, which works about as fast as in Xaos. Very handy feature is that you can drag the actual palette with the mouse.

You can tune the palettes way more than in Xaos, but still I want to tune it even further.

Source: http://jwm-art.net/mdz/


Kalles Fraktaler
Much more manually tuning possible here. I only wish I could adjust the infinite color waves just as the color channels in MDZ. And also the blending stuff as in MDZ, but combined with the layer modes of the Gimp.

Source: http://www.chillheimer.de/kallesfraktaler/


All tuning on the palette should be instantly visible on the actual fractal. Tuning should be both ways (sliders on values and UDNO function!) and should be smart. For example zoom or iteration dependant. For example think about changing the palette density. It would be nice if the most visible color on the actual fractal on screen was chosen as the "zero" point from which the scaling is done. This way the visible colors don't jump out of sight while adjusting.

I have no experience with Ultra Fractal.

If you want to please most users, then make it as easy (smart randomizers) as possible while leaving room for optional (bit hidden) manual tuning.

[3dickulus]

@youhn thanks for the palette control rundown of these popular packages

@zenzero-2001 on the face of it, the user should be able to get a really nice palette with just a few clicks and twiddles, something I've been toying with
have a look at this short vid of my palette scheme in action, you can paint a 256x256 swatch of blended, flowing or/and sharp lines and shapesto make some really cool palette cycling effects

each line of the "swatch" is used as a list of 256 key colors that get spread over the color map size
it is essentially a per frame palette list that will enable some very subtle and smooth color control over the course of an animation.

it can load an image (auto scaled for you) of a favorite landscape or garden scene for a real organic palette.

the vid was made with this image as a palette list.

[youhn]

Wwoooww... you created color cycling both ways at the same time!

    

I've thought of that before ... just can't really program (good enough).

[3dickulus]

you can doodle in the graph areas with the mouse too 

[zenzero-2001]

Thanks for the info youhn. Lots for me to think about. I have mdz compiled on my machine, so will have a good look at its palette editor.

3dickulus, your palette scheme looks very cool. :-)

So far, my gradient editor is pretty simple to use. It has full undo and redo, as well as being able to choose linear or cubic interpolation, just like Ultra Fractal in fact. You can add and remove nodes and save / load gradients. I'm in two minds whether to keep it as it is or make the colour channels totally independent.

I attach a couple of images of the editor for you to get an idea of how it works. You can see that each node exists in all three of the shade widgets. Deleting a node from one shade widger will delete it from the other two widgets also. You can see that the saw-tooth gradient requires extra nodes to define it compared to if the channels were independent.

[zenzero-2001]

Also, the fractal colours change immediately in response to changes in the gradient editor.

[panzerboy]

Fractal Extreme has impressive control point selection.
You click on a control point, shift click on extra points and adjust them as a group.
You can use a bounding box select to select say the top value control points, and again shift bound box to add points.
Right click -> select all to select all the control points for a channel.
Copy and paste. A trick I use to create a stripe palette is to select all three channels from the main palette and copy them.
Then scroll the palette left or right an even number of steps.
Show stripes and edit odd, right click replace paste, now the stripes are a slightly offset copy of the main palette.

A preview copy limited to 100 zooms is available at cygnus-software.com, have a play, its just the slickest palette editor I've used.

Internally Fractal Extreme  keeps the position and value for each 'node'
ie. it doesn't create green & blue values if you set a red value at a position.
That possibly makes it easier for it to perform it's tricks?

Are you making an 'import' option from a text file, or the palette file editable?
For Kalles Fraktaler & Mandel Machine my preferred palette tools are Open Office Calc (Spreadsheet) and Notepad++ 

[zenzero-2001]

Thanks for the suggestion of Fractal eXtreme panzerboy, I have a licensed version so will give it a whirl.

Ultra Fractal has the linked nodes and also has the ability to select multiple nodes, not sure if it can do the same tricks as Fractal eXtreme though.

I wasn't planning on having an import option from a text file, but maybe it is something for me to consider. The gradient / palette file is currently saved in a binary format and is not editable. If I make it editable, I will have to program some code to validate it on loading.

I've not tried Mandel Machine yet (I run a Linux box), it looks very impressive from what I have seen so far. Sometimes, I think my program is quite good (using SSE2 for the Mandelbrot calculation and having arbitrary precision with MPFR) and then I am humbled by other great software :-) I've only given Kalles Fraktaler a quick go. Both Kalles Fraktaler and Mandel Machine appear to be on the cutting edge with regards to speed optimisations (as is Fractal eXtreme).

I am currently leaning towards making the color channels completely independent, but haven't made a final decision.