mesa3d-users

[Mesa3d-users] Anti-aliasing lines Intel GMA 4500 question

[Stefan P. <sp...@sy...>]

Hi all,

Im currently developing a prototype as described here:
http://www.systemdatarecorder.org/cpuplayer/ using OpenGL.
Im basically working on Solaris x64 + Nvidia and Ubuntu
x64 + Mesa as main platforms.

Im trying to understand why my code does not execute similar
regarding Anti-aliasing, as described under:
http://systemdatarecorder.org:9009/bugzilla/show_bug.cgi?id=42

Check the Solaris 11 and Ubuntu screenshots attached.

On my Ubuntu laptop Im using:
direct rendering: Yes
OpenGL renderer string: Mesa DRI Mobile Intel GM45 Express Chipset GEM 
20090712 2009Q2 RC3

This is a Ubuntu 9.10 x64 using Intel GMA 4500 MHD, running Mesa 7.6.0-1.

Any ideas, is this a problem with Mesa OpenGL implementation, is this
a Intel driver bug or ... !?

Many thanks,
Stefan

Re: [Mesa3d-users] Anti-aliasing lines Intel GMA 4500 question

[Brian P. <br...@vm...>]

Stefan Parvu wrote:
> Hi all,
> 
> Im currently developing a prototype as described here:
> http://www.systemdatarecorder.org/cpuplayer/ using OpenGL.
> Im basically working on Solaris x64 + Nvidia and Ubuntu
> x64 + Mesa as main platforms.
> 
> Im trying to understand why my code does not execute similar
> regarding Anti-aliasing, as described under:
> http://systemdatarecorder.org:9009/bugzilla/show_bug.cgi?id=42
> 
> Check the Solaris 11 and Ubuntu screenshots attached.

I don't see any attachments.


> On my Ubuntu laptop Im using:
> direct rendering: Yes
> OpenGL renderer string: Mesa DRI Mobile Intel GM45 Express Chipset GEM 
> 20090712 2009Q2 RC3
> 
> This is a Ubuntu 9.10 x64 using Intel GMA 4500 MHD, running Mesa 7.6.0-1.
> 
> Any ideas, is this a problem with Mesa OpenGL implementation, is this
> a Intel driver bug or ... !?

Are you talking about line antialiasing?

I think the 4500 has some limitations w.r.t. antialiased lines.  You 
might try settting the INTEL_STRICT_CONFORMANCE env var to 1 and see 
what happens.  This will turn on software-drawn AA lines.  Performance 
will be poor, however.

-Brian

Re: [Mesa3d-users] Anti-aliasing lines Intel GMA 4500 question

[Stefan P. <sp...@sy...>]

Hi,

> I don't see any attachments.

Probable hidden a bit inside bugzilla.

Here you go:

  Ubuntu intel gma4500:
  http://systemdatarecorder.org:9009/bugzilla/attachment.cgi?id=1

  Solaris nvidia:
  http://systemdatarecorder.org:9009/bugzilla/attachment.cgi?id=2

> Are you talking about line antialiasing?

yep. Im just plotting the Barry coordinates using a simple sequence
like:

         /* Enable Anti-aliasing and width of axis */
         glEnable(GL_LINE_SMOOTH);
         glEnable(GL_BLEND);
         glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
         /* glHint(GL_LINE_SMOOTH_HINT, GL_DONT_CARE); */
         glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
         glLineWidth(0.5);


         glBegin(GL_LINES);

             /* draw axis */
             /* Usr Red */
 	    glColor3f (1.0f, 0.0f, 0.0f);
 	    glVertex2f(b3Vertex[1][0], b3Vertex[1][1]);
 	    glVertex2f(op_usr.x, op_usr.y);

             ...

         glEnd();

> I think the 4500 has some limitations w.r.t. antialiased lines.  You might 
> try settting the INTEL_STRICT_CONFORMANCE env var to 1 and see what happens. 
> This will turn on software-drawn AA lines.  Performance will be poor, 
> however.

thanks. I will try this. I will report back the results.

stefan

[1] http://www.systemdatarecorder.org/cpuplayer/src/cpuplayer.c

Re: [Mesa3d-users] Anti-aliasing lines Intel GMA 4500 question

[Brian P. <br...@vm...>]

Stefan Parvu wrote:
> Hi,
> 
>> I don't see any attachments.
> 
> Probable hidden a bit inside bugzilla.
> 
> Here you go:
> 
>   Ubuntu intel gma4500:
>   http://systemdatarecorder.org:9009/bugzilla/attachment.cgi?id=1
> 
>   Solaris nvidia:
>   http://systemdatarecorder.org:9009/bugzilla/attachment.cgi?id=2
> 
>> Are you talking about line antialiasing?
> 
> yep. Im just plotting the Barry coordinates using a simple sequence
> like:
> 
>          /* Enable Anti-aliasing and width of axis */
>          glEnable(GL_LINE_SMOOTH);
>          glEnable(GL_BLEND);
>          glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
>          /* glHint(GL_LINE_SMOOTH_HINT, GL_DONT_CARE); */
>          glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
>          glLineWidth(0.5);
> 
> 
>          glBegin(GL_LINES);
> 
>              /* draw axis */
>              /* Usr Red */
>  	    glColor3f (1.0f, 0.0f, 0.0f);
>  	    glVertex2f(b3Vertex[1][0], b3Vertex[1][1]);
>  	    glVertex2f(op_usr.x, op_usr.y);
> 
>              ...
> 
>          glEnd();
> 
>> I think the 4500 has some limitations w.r.t. antialiased lines.  You might 
>> try settting the INTEL_STRICT_CONFORMANCE env var to 1 and see what happens. 
>> This will turn on software-drawn AA lines.  Performance will be poor, 
>> however.
> 
> thanks. I will try this. I will report back the results.

Just be aware that the quality of AA lines from one GPU/driver to 
another can vary a lot.  I think NVIDIA may have higher quality AA 
lines than other GPUs.

-Brian

Re: [Mesa3d-users] Anti-aliasing lines Intel GMA 4500 question

[Stefan P. <sp...@sy...>]

>
> Just be aware that the quality of AA lines from one GPU/driver to another can 
> vary a lot.  I think NVIDIA may have higher quality AA lines than other GPUs.

setting INTEL_STRICT_CONFORMANCE did not bring any difference.

Probable this is a driver issue. The difference is big: on Intel
Im not even capable of seeing all coordinates properly set:
http://systemdatarecorder.org:9009/bugzilla/attachment.cgi?id=1
(missing the red axis) If I resize the window then I get properly
the coordinates set and all lines displayed :)

On Nvidia the quality of AA lines is higher and the lines are
properly set from start.

Probable not much I can do. I will try to test on a different machine,
using ATI and Solairs or Linux to see the difference.

Thanks,
Stefan

Re: [Mesa3d-users] Anti-aliasing lines Intel GMA 4500 question

[Stefan P. <sp...@sy...>]

Hi Brian,

Probable this would make things clear:

Nvidia:
  OpenGL vendor string: NVIDIA Corporation
  OpenGL renderer string: Quadro FX 1500/PCI/SSE2
  OpenGL version string: 2.1.2 NVIDIA 190.53

  GL_LINE_WIDTH_GRANULARITY = 0.1
  GL_LINE_WIDTH_RANGE = 0.5 10.0


Intel:
  OpenGL vendor string: Tungsten Graphics, Inc
  OpenGL renderer string: Mesa DRI Mobile Intel GM45 Express Chipset
                          GEM 20090712 2009Q2 RC3
  OpenGL version string: 2.1 Mesa 7.6
  GL_LINE_WIDTH_GRANULARITY = 0.5
  GL_LINE_WIDTH_RANGE = 1.0 5.0

As you said with NVIDIA I have much higher degree and better quality.
So this looks specific to each OpenGL implementation. Question is why in 
Mesa we have GL_LINE_WIDTH_GRANULARITY = 0.5 instead of 0.1 like in NVIDIA 
case ? Is it direct dependant of the GPU, or the driver ... !?

Many thanks,
Stefan

Re: [Mesa3d-users] Anti-aliasing lines Intel GMA 4500 question

[Brian P. <br...@vm...>]

Stefan Parvu wrote:
> Hi Brian,
> 
> Probable this would make things clear:
> 
> Nvidia:
>   OpenGL vendor string: NVIDIA Corporation
>   OpenGL renderer string: Quadro FX 1500/PCI/SSE2
>   OpenGL version string: 2.1.2 NVIDIA 190.53
> 
>   GL_LINE_WIDTH_GRANULARITY = 0.1
>   GL_LINE_WIDTH_RANGE = 0.5 10.0
> 
> 
> Intel:
>   OpenGL vendor string: Tungsten Graphics, Inc
>   OpenGL renderer string: Mesa DRI Mobile Intel GM45 Express Chipset
>                           GEM 20090712 2009Q2 RC3
>   OpenGL version string: 2.1 Mesa 7.6
>   GL_LINE_WIDTH_GRANULARITY = 0.5
>   GL_LINE_WIDTH_RANGE = 1.0 5.0
> 
> As you said with NVIDIA I have much higher degree and better quality.
> So this looks specific to each OpenGL implementation. Question is why in 
> Mesa we have GL_LINE_WIDTH_GRANULARITY = 0.5 instead of 0.1 like in NVIDIA 
> case ? Is it direct dependant of the GPU, or the driver ... !?

The Intel i965 line width register only has one fractional bit.

-Brian

Re: [Mesa3d-users] Anti-aliasing lines Intel GMA 4500 question

[Stefan P. <sp...@sy...>]

> The Intel i965 line width register only has one fractional bit.

aha. Clear enough. Makes sense.
stefan