MATHCOMP: icebrot

[Rbz]

Yep, the background still black...

What card is it? Is it Ati or Nvidia?

nVidia - Geforce 6600GT


Sorry if I can't help more, I don't know anything about pixel shaders yet 

Thanks to trying fix this...

[slinks]

My computer is dieing just looking at the complexity of the screenshots, I'd better leave this one alone! 

[taj]

One last attempt tonight...

thanks for the help rbraz,karma up anyway. After this ill implement a whole set of error reporting and nail this puppy, but not tonight - too much vodka.

[Rbz]

Sorry, still black

Btw, I'll update my gfx driver, maybe that help too...

[taj]

OK either a) Nvidia drivers are non-compliant or b) ati ... I know where my money is.

[Rbz]

Damn, black background again...

[taj]

Rbraz,

thanks for all the patience. I did some internet searching and it seems lots of people have problems with shaders on 6600. So, for now anyway I''m officially giving up. It could be my code of course but for the moment, I cant see a problem.

Damn, to do shaders you need about 10 PCs for testing. Its ridiculous. Really it is.

[Rbz]

I updated my graphic board drivers and run your tests again:

rbraz32dm.exe  - works fine - I can see the fluid fractal and background is black, colors are ok..
rbraz8loop.exe  - works fine - I can see the fluid fractal and background is white, colors are ok..
rbraznocos.exe - works fine - I can see the fluid fractal and background is black, colors are ok..
rbraznomix.exe - works fine - I can see the fluid fractal and background is black, colors are ok..

And now your 1kb is working fine too, but with black background 

[taj]

Rbraz,

OK so given you get a white background now with new drivers, its a memory issue, the number of loops is critical to success on different cards. The one I gave you looped only 8 tmes, and is white - the correct colour. The one I published loops 14 times and somehow causes your card to get an incorrect result.

It seems, shaders are very prone to problems: even a correct shader will not necessarily work. Great example this loop in mandelbrot. On my x1900 it works up to about 30 loops, on my x800 up to 14 and on your nvidia 6600, at least up to 8 but not up to 14. Other things, ati cards fall back to software rendering as soon as you use a variable as the loop counter: again not a language problem but a card problem. I assume that the compiler is loop unrolling depending on the fixed loop number and not really processing a loop on the card at all (which also explains the lack of memory and limit on loop size). Lastly gl_Color is supposed to be available in both vertex and pixel shaders but on my ati cards although gl_color is not available in pixel shaders (you have to copy it and pass it through another variable, wasting bytes).

Overall, its easy to see why there arent so many intros relying on loops and iteration in shaders.   

Shaders for sure are a very immature technology. Rbraz thanks again for helping me to understand this. Have a drop more Karma.

[lilw4t3rdr0p]

I use to blow glass in college and it looks like some of the designs that can be made inside the glass. I always loved them, so in-turn I love this!