Brian Paul wrote:
> Eric Anholt wrote:
>> On Fri, 2008-06-06 at 09:45 +0200, Tomas Carnecky wrote:
>>> Some fragment shaders don't work right on i965. For example if I enable 
>>> the 'neg' compiz plugin, all windows turn gray. And I tried my own 
>>> plugin that does: MOV output.r, 1.0; and all windows turned red (or was 
>>> it gray also? I don't remember...). I was told it's an issue in Mesa 
>>> rather then the drivers. But I couldn't find any bug report describing 
>>> that problem (not under mesa nor the xorg intel driver). Do you want me 
>>> to open a new bug?
>>> If you tell me where in mesa the bug could be, I'll try to look into it 
>>> myself (as time permits). I really need shaders. Even thought these work 
>>> fine on my desktop (nvidia blob), I'd like to be able to hack when on my 
>>> laptop.
>> We're always interested in short samples of code that fails on our
>> driver.  Unfortunately, "configure compiz and enable a magic set of
>> plugins" is kind of a high barrier to entry for bugfixing, and thus less
>> likely to be poked at in one's spare time.
> 
> Yup.
> 
> Above, Tomas wrote:  "And I tried my own plugin that does: MOV output.r, 
> 1.0; and all windows turned red (or was it gray also? I don't remember...)"
> 
> If all your fragment shader does is MOV output.r, 1.0; you're saying the 
> output color's R channel will be 1.0 and the GBA channels will be 
> undefined/random.  I wouldn't blame Mesa or the driver if you wound up 
> with a red window.

I'm sorry, turns out I have a different problem. I need to create a 
plugin for compiz that uses shaders and I was experimenting and trying 
to figure out how compiz works. Compiz doesn't have any API 
documentation, not even comments in the code. It's a nightmare.

Anyway, I brought it down to this: When I bind a texture to 
GL_TEXTURE_RECTANGLE_ARB and then use the following fragment program code:

TEX tu, fragment.texcoords[0], texture[0], RECT

then I have to supply normalized texture coordinates (ie. in the range 
[0 .. 1]). As far as I understand the ARB_texture_rectangle spec, when 
the texture is bound to the RECTANGLE target then the coordinates should 
be non-normalized.

I even have a small application that demonstrates the problem. If this 
is a new bug to you, should I open a bug and attach the app to it?

tom

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