Re: [Mesa3d-dev] Calling glGetError during glBegin/End

[Keith W. <ke...@va...>]

Allen Barnett wrote:
> 
> Hi,
> 
> While trying to diagnose a rendering problem with my code, I added a
> call to glGetError after each glVertex call between glBegin and glEnd.
> With Mesa compiled with debugging turned on, _mesa_error was reporting
> INVALID OPERATION to stdout even though glGetError itself returned 0.
> According to the man page, this is the correct result but it also
> mentions that there should be no other side effects. However, when
> calling glGetError, the FLUSH_VERTICES macro is invoked by the
> ASSERT_OUTSIDE_BEGIN_END_WITH_RETVAL macro at the beginning of
> _mesa_GetError. This seems to have a (negative) effect on the display
> list which is being constructed.
> 


This is a trap; glGetError is *not* allowed between Begin/End pairs, and is
required to generate the error you are seeing.

Keith