[Mesa-dev] [PATCH 5/5] i965: Stop XY clipping point and line primitives.

[Roland Scheidegger]

Am 11.03.2016 um 03:50 schrieb Kenneth Graunke:
> On Friday, March 11, 2016 2:50:46 AM PST Roland Scheidegger wrote:
>> Technically, this is still wrong for rendering traditional gl points,
>> which indeed require points either be drawn in full (even the parts
>> outside viewport, if the center is inside viewport) or not at all (if
>> the center is outside viewport). Albeit the gles language may be
>> different (and looks like gets cleared up even) the rules for gl are
>> still the same
>> However, just about everybody seems to hate the traditional point
>> clipping, and some vendors never implemented it that way anyway (or did
>> so on a case-by-case base even depending on whatever...). (d3d9 rules
>> required it the same as what you're doing in this change here fwiw, so
>> same as gles, whereas d3d10 "fixed" this problem by not actually
>> supporting large points at all...)
>>
>> Roland
> 
> Exactly.  I originally thought the test was broken.  I think ES
> clarifies the language, but it doesn't actually specify *this*
> behavior yet.
> 
> It seems like most vendors implement this behavior, and it's the
> behavior that people actually seem to want.  Based on the bug entry,
> it seems people were generally in favor of trying to write new language
> to support this behavior.  But it stalled in 2014.
> 
> https://cvs.khronos.org/bugzilla/show_bug.cgi?id=10698
> 
> It's kind of sketchy.
> 

Oh I skimmed through the bug and thought the proposal to fix the spec
language was only for ES (which is already different to GL here), not
GL. But that doesn't look to be entirely the case, albeit it's not quite
clear (the part to change GL seems to be more of some informal
request)... And I just assumed newer gles versions would already have
the new language as the bug is quite old, there seemed to be some
agreement to change it, but nothing happened strangely enough so gles
3.1 and 3.2 still indeed have the same wording...

Roland