[Mesa-dev] [PATCH 03/16] mesa: Clamps the stencil value masks to GLint when queried

[Eduardo Lima Mitev]

On 12/18/2014 10:28 AM, Eduardo Lima Mitev wrote:
> On 12/18/2014 09:55 AM, Olivier Galibert wrote:
>> Something is not clear to me: In which way -1 is incorrect?
>>
> 
> Hi Olivier,
> 
> The values being queried are the front and back stencil masks. Masks are
> (conceptually?) an unsigned integer, AFAIU. 

Well, more accurately, just a string of bits, so -1 (or any other value)
is probably fine. Problem is when the signed integer value is further
converted to float, which is the case for these failing tests. (Note
that only the test cases that query the mask as a float value are the
ones failing).

Giving a bit more of thought to this, and assuming the test is fine
querying for a mask value using the glGetFloat API, the problem is Mesa
converting from unsigned int (the mask) to signed int, then to float;
instead of converting to float directly. I don't have a say on why it
does that intermediate conversion to int, though.

So my original solution was wrong from different angles, and the final
solution is probably not the best one either, since we are "avoiding"
the type conversion problem rather than fixing it.

Thanks for rising these points.

Eduardo