945GM/I810 OpenGL issue

[Brian Paul]

Rogers Simon wrote:
> 
>> -----Original Message-----
>> From: xorg-bounces at lists.freedesktop.org [mailto:xorg-
>> bounces at lists.freedesktop.org] On Behalf Of Brian Paul
>> Sent: 07 November 2007 21:31
>> To: Simon Rogers
>> Cc: xorg at lists.freedesktop.org
>> Subject: Re: 945GM/I810 OpenGL issue
>>
>> Simon Rogers wrote:
>>> Hi
>>>
>>> I have two laptops with Intel 945GM gfx, both running CentOS 5. The Xorg
>>> log reports build ID xorg-x11-server 1.1.1-48.13.el5. Kernel 2.6.18-8. I
>>> also tested this on Ubuntu Gutsy, with the same result.
>>>
>>> The problem: If I define a polygon stipple with horizontal or vertical,
>>> one pixel wide stripes, my test app runs at ~300FPS. If I change this
>>> stipple pattern to anything else, performance drops by a factor of 10.
>>>
>>> I can provide test source code to demonstrate.
>>>
>>> Apologies if this is the wrong forum.
>> The i945 hardware only supports a 4x4 stipple pattern.  If the GL
>> polygon stipple isn't a 4x4 repeating pattern you'll get a software
>> fallback.
>>
>> -Brian
> 
> Thanks for this info - is there any way I could have found this out without you telling me?

I guess you'd have to look at the code.

> Are there any similar line stipple limits?

i945 doesn't have a line stipple, at least not in 3D mode, so that's a 
fallback.

> What about the GL_LINE_WIDTH_RANGE which is 1.0 - 3.0. Is this a hardware related limit or can it be increased (compare to my Radeon laptop which can do 1.0 - 64.0)?

I thought the line width limit was 7 pixels.  I'd have to check.

-Brian