Mandelbulb Composition

Whoa!

Cool! I've been wanting to play with that for a while. The shader seems good.. reasonably fast on my radeon 2600, with decent quality.

But... it really, really needs decent controls. I think ideally it should have something like 'look around with mouse, buttons to move forwards/back', so you can pretty much fly around. It has rotation and translation already, perhaps it's possible without much messing about?

The problem though is you want the speed of motion to slow down the closer you get to the surface. Wonder if it's possible to get the Z value out of the shader, maybe with toneburst's "put z in the alpha channel" method? Then you could easily determine the rough distance from the surface in front of the camera.

"Part of the new Xcode".... hahahah....

It looks like camera z is wrong (... it does what looks like a y translation to me). Cam Y looks like it's supposed to be Cam Z (?). Also, the zoom seems odd... I would expect to keep seeing more detail as I zoom in, but it's limited to 1 at the insert splitter, and doesn't work that way (eg., it doesn't get more detailed with zoom). I guess that's par for the course... but supposedly it's supposed to reveal more detail (according to the article). I think it falls completely flat on that claim, though I haven't tweaked it much.

It's like the original mandelbrot - a lot of it consists of big fat solid bands. Look into the right places though (try the holes) and you'll see the detail in there. The y/z axes are a bit odd - but picture yourself looking down at it and it makes a little more sense.

All this just reinforces my claim that it needs some cool controls adding :) I'd have a mess but I'm in the middle of some iphone coding.

Yeah, but I'm not on top of it looking down :) I'm in front of it.

I saw some clips on Vimeo last week, and was waiting for the promised writeup on his blog. Missed it when it finally came though. Impressive stuff indeed...

a|x

Thanks for the comments guys.

To reveal more detail as you zoom in you have to actually move closer to the surface of the fractal. The camera zoom option in effect changes the focal length of the camera but doesn't move the eye any closer. The raytracing threshold is optimised based on the distance from the surface, hence you have to move closer to reveal more detail.

You can see the effect of this here: http://www.vimeo.com/8148760

If you are interested in getting the most out of it I would also recommend reading the instructions I've posted on its project page: http://www.subblue.com/projects/mandelbulb

My comment about lack of detail was definitely when using the correct controls, but when using the quick version... when I use the full-on version, it's way better.

I still find the choice of y for front to back zoom to be odd, but that's me I guess... I would find any qtz that used y for that to be odd, not just this one. I can't think of anytime that I would plot x/y/z and not have z be parallel to the ground. Is this some kind of historic fractal thing (it doesn't seem like it to me)? I don't see that in other fractal stuff, but then again, that stuff is 2D.

BTW, awesome blog Tom, really interesting.

That's a really impressive bit of GLSL shading via way of Pixel Blender Toolkit. The quick version reminds me of those heady 256 colour fractal days of yore :-)