Re: fltk rendering problem

[Martin Helm]

Am 18.10.2012 21:19, schrieb Mike Miller:
> On Fri, Oct 12, 2012 at 2:47 PM, Martin Helm wrote:
>> Am 12.10.2012 20:38, schrieb Dmitri A. Sergatskov:
>>> On Fri, Oct 12, 2012 at 10:41 AM, Martin Helm <address@hidden>
>>> wrote: ...
>>>> So it is not a problem of the graphics card driver or the mesa
>>>> version.
>>> ...
>>>
>>> FWIW:
>>>
>>> I see this problem on the computer with intel graphics
>>> (i7-2600k/DZ68 m/b) and I do not see on the computer with an
>>> nvidia card (and nvidia driver). (GF106GL [Quadro 2000])
>>>
>>> Dmitri. --
>> As I said I see exactly the same behavior (we have intel gpu and
>> nvidia gpu machines at home, all GNU/Linux systems), it is still
>> not a driver issue as my own test shows me. The issue seems to be
>> that something in octave (I will investigate the details over the
>> weekend) simply does not set proper state variables for opengl and
>> instead relies on whatever the implementation on the machine does
>> as default. This is rarely what one would like to have. So far I
>> can also not understand what sense it makes to set a linewidth of
>> 0.5 without at the same time enabling antialiasing, the behavior
>> what an opengl implementation shall do in such a case seems to be
>> undefined. The nvidia driver just renders it aliased with a line
>> width of 1, the intel+mesa implementation seems to try to render
>> "half" of the points. So if by default we want aliased rendering we
>> should probably have a default line width which is an integer, not
>> a fraction which cannot be rendered in a defined way.
>
> Thanks for looking into this Martin. I guess I might as well post to
> the bug tracker so we don't forget about this. Could you also share
> the small opengl antialiasing test code you wrote?
>
Will do as soon as I am back at home on Friday evening (I am on a
business trip at the moment), I hope I can propose some patch to solve this.
Please add an entry to the bug tracker.