[osg-users] Please test OpenSceneGraph-3.6 branch in prep for 3.6.1

[Terry Welsh]

Thank you, Dan. That is *exactly* the problem I have with the Intel
graphics driver. This bug affects a driver from September and the new
one I installed last night. I'll test your workaround when I get home
tonight and report on it.

(My AMD driver, on the other hand, is a complete mess. It crashes on
Furmark and pretty much everything else.)

Robert, here is a related suggestion: how about renaming text.vert and
text.frag to something unique? Maybe osgtext_text.frag? When I first
tried 3.6.0 all my text was very broken because I already had a
text.vert and text.frag in my application. It took a while to figure
out that they were being loaded by osgText::Text even though I had
disabled them in my own code.
- Terry

>
> Hi Terry,
>
> Hey I might know this one.  Thanks for that additional info about your driver.  Do you mind retesting with a change?
>
> See references:
>
> - https://devtalk.nvidia.com/default/topic/971330/opengl/bug-report-crash-in-glcompileshader-if-using-pragma/
> - https://software.intel.com/en-us/forums/graphics-driver-bug-reporting/topic/623485
> - https://github.com/gwaldron/osgearth/issues/1017
> - https://github.com/gwaldron/osgearth/pull/1106
> - https://github.com/gwaldron/osgearth/pull/1100
>
> There are some older intel drivers that crash on shaders that include pragmas with too many "arguments".  The spec says that pragmas should be ignored.  But testing demonstrates severe problems with several intel drivers over a few years' period where lines like:
>
> #pragma import_defines( BACKDROP_COLOR, SHADOW, OUTLINE, SIGNED_DISTANCE_FIELD, TEXTURE_DIMENSION, GLYPH_DIMENSION)
>
> ... could cause a failure.  Breaking it up into separate lines of no more than 2 arguments each works.
>
> We found that the magic number for drivers is 3 -- once you get over 3 parameters, it starts to break (depending on driver version).  Could you try to edit your text.frag file to change:
>
> #pragma import_defines( BACKDROP_COLOR, SHADOW, OUTLINE, SIGNED_DISTANCE_FIELD, TEXTURE_DIMENSION, GLYPH_DIMENSION)
>
> To:
>
> #pragma import_defines( BACKDROP_COLOR, SHADOW, OUTLINE)
> #pragma import_defines( SIGNED_DISTANCE_FIELD, TEXTURE_DIMENSION, GLYPH_DIMENSION)
>
> This breaks it into 2 lines of 3 params each.  If it's the same bug that we encountered, this might fixyour problem.
>
> Robert, I haven't reported this because we haven't explicitly ran into this same problem with 3.6 and text shaders yet, because we haven't run on those drivers.  Newer drivers do fix the issue.
>
>  - Dan
>