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Old 9th December 2010, 02:10   #1
Eo.S.
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I figured out why Pixel Shader 3 presets don't work on ATI

Having run milkdrop through Microsoft's directx debugging tool PIX, I noticed that for presets that are running in pixel shader 3.0 mode, the vertex shader's are all compiled as shader model 1.1, while the pixel shaders are compiled as model 3.0.
ATI cards will not run ver 3.0 pixel shaders with non 3.0 vertex shaders. Any version of pixel shader below 3.0 can be combined with lesser versions of vertex shader, which is why 2.0 and 2.x presets still work in Milkdrop 2.

DirectX will actually issue a warning in regards to this, but not an actual error so it can be missed during development if using NVidia GPUs. I'm familiar with the error because Rendermonkey issues the warning. When I use Rendermonkey on our ATI GPU computers I have to set the vertex shader to compile for vs3.0 whenever I set the pixel shader to use PS3.0 or it doesn't render. On our Nvidia GPU computers it still issues the warning, but the GPU allows it and still renders.

This is a very easy fix codewise, as the fxc compiler just needs to be given the flag to compile VS as 3.0 for PS3 presets, so hopefully a winamp developer with access to the MD2 source can implement this fix.

It's possible this may not be the only issue, but having spent the last 6 years programming on both ATI/Nvidia GPUs I'm pretty positive this should be the whole of it.

Eo.S.
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Old 9th December 2010, 17:58   #2
Nitorami
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Great. I would not be so optimistic though about someone@winamp fixing it.

To me, the most annyoing issue with MD is that it has a strong tendency to crash the entire machine when you use the "mini-mashup" (A) key. Press it, then terminate milkdrop. Reinvoke it, and it will normally already cause an illegal operation.
Terminating winamp after having used the A key will also reliably cause a crash, sometimes leaving a process in the background which keeps the machine so busy you cannot even call up the task manager. Absolutely unacceptable. That was introduced more than a year ago and not fixed since. But what can we expect when they won't even fix trivial issues such as the pow function... according to MD per frame calculation, pow (0.999,1) = 1.0044.
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Old 14th December 2010, 06:19   #3
Phat
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I just wish everything was still open source. It wouldn't be super hard stuff to fix. I don't even understand what anyone has to gain from the program not being open source. Winamp is a free download, so is Milkdrop 2.
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Old 14th December 2010, 16:25   #4
Zylot
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This would be nice, being as I was gifted a Radeon HD and it runs everything so nice but then I get the <flacker,nothing,haha,die> on some presets.

@staff: please to impliment simple fix thanx?

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Old 14th December 2010, 20:43   #5
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@Nitorami: benski has tried to fix the issue with you but if it's not easily possible to resolve it then how can it be fixed. you know where to post to keep pestering about it.

Quote:
Originally Posted by Nitorami View Post
But what can we expect when they won't even fix trivial issues such as the pow function... according to MD per frame calculation, pow (0.999,1) = 1.0044.
have you reported it to the betalist? no one generally checks down in here very frequently and that's the first i've heard of such an issue - where has this been described / otherwise reported?

@everyone: is only by chance i've seen activity in here though will pass it on to see what can be done.

-daz
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Old 14th December 2010, 22:24   #6
Nitorami
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@DrO - I know that Benski confirmed the crash problem and made some attempts to fix it but without success so far. For more than a year now, winamp can be crashed with a single keystroke.

On the pow function - yes of course I reported that but it was not fixed likewise. It is a problem for presets that use a frame independant decay rate such as decay = pow (0.98, 30/fps). On fast machines with fps > 70 or so, decay will be > 1 and the code will become unstable.
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