new WebGL application to explore 3D fractals

[David Makin]

For those experiencing distortion when undersampling: Please try this version and see if it improves anything http://dl.dropbox.com/u/6556492/Raymarching/index.html

That fixes the undersampling on my machine (OSX, ATI 4850)

Fixes it on Firefox for my 5870 too - still no joy via Safari WebKit though.

[DrColossus]

We just updated it on the server:

http://projekte.sinnpirat.de/fraktal/

It looks like there is a bug in ANGLE that we worked around which broke it for a lot of configurations.
gl_FragCoord.y apparently returns way too large values on some machines, and we're using a negative offset to compensate for that.
There is branching in place now that should detect a users config and set the negative offset value accordingly, but you can still override it with a toggle button on the bottom to the left.
When disabling ANGLE in Firefox on windows undersampling should work now, well, sort of, the image was black for us when moving the camera haha

We also implemented a variable field of view and the ability to cut the fractal along the x-/y-/z-axis:

The latest stable version of Chrome for OSX has a bug in the cos function (!!) - I reported it last September... I'm using this for compatibility in my shaders:

Code:

#define HALFPI 1.570796
#define cos(a) sin(a + HALFPI)

Thanks for the tip, we added your code
What was the bug?

Tried the dropbox version, and it still fails (both Firefox (without ANGLE)  and Chrome) - but looks different now.

chrome://version/ = 16.0.912.75 (Official Build 116452) m (Vista, 32bit)

GTX570 drivers are version: 285.62 (Oct 2011) - these are the latest official ones - yours must be beta drivers, right?

Yep, i'm using beta drivers. The artifacts you're seeing are weird and i wasn't able to reproduce them
Maybe our newer version fixes that?


Please bare with us, since we are just three students
And WebGL gives us a lot of headaches, especially ANGLE which we even didn't know existed up until today.

[subblue]

Thanks for the tip, we added your code
What was the bug?

The bug incorrectly reports itself as "ERROR: 0:5: 'webgl_emu_precision' : syntax error syntax error", but is triggered when you try and use the cos function. It's still occurring in the postProcess.fs so you should add it there too

[DrColossus]

Thanks for the tip, we added your code
What was the bug?

The bug incorrectly reports itself as "ERROR: 0:5: 'webgl_emu_precision' : syntax error syntax error", but is triggered when you try and use the cos function. It's still occurring in the postProcess.fs so you should add it there too

Oh wow, thank you very much!
We just added it to the postprocessing as well.

Oh, and your blog was actually a big help to us in developing this app

Fixes it on Firefox for my 5870 too - still no joy via Safari WebKit though.

Hmm, i just tried it on my macbook using Safari 5.1.1 and got a black screen, i had to enable webgl in safaris debug menu.
To enable the debug menu, type this into the OSX terminal:

Code:

sudo defaults write com.apple.Safari IncludeDebugMenu 1

It's still not perfect though, the fractal appears black for me when i move the camera o_O


edit:
We just made some more small improvements in our shadow rendering, those dark rings on flat surfaces should be gone now.

[Syntopia]

I tried again on my 310M, and it is still the same - the undersampling is slightly offset, on both Firefox (without Angle) and Chrome.

[DrColossus]

I tried again on my 310M, and it is still the same - the undersampling is slightly offset, on both Firefox (without Angle) and Chrome.

Does this version look any better?  http://dl.dropbox.com/u/6556492/Raymarching/index.html

If it doesn't, then i have absolutely no idea what could be causing that offset

[cKleinhuis]

my browser ff9.01 crashes instantly, graphics card is amd radeon 6800....
the browser just freezes, with a black screen and the gui ....


what about sliders in the gui ?! i love turning sliders when gpu is used!

[DrColossus]

my browser ff9.01 crashes instantly, graphics card is amd radeon 6800....
the browser just freezes, with a black screen and the gui ....


what about sliders in the gui ?! i love turning sliders when gpu is used!

Firefox provides quite some issues for us, you have to disable ANGLE for it to work (type "about:config" into your adress bar and set "webgl.prefer-native-gl" to true).
We're also still trying to figure out why the sliders don't work in the Windows version of Firefox (they show up fine in OSX or other browsers).

If it still fails with ANGLE disabled, please consider trying Google Chrome for this application.

I'll edit the first post regarding the Firefox crashes.