[osg-users] Bug in GeometryShaders causing OpenGL Error

[Art Tevs]

Hi Mike.

Maybe it is a driver bug, yes. The repro code is the
example code of the osgPPU (projects.tevs.eu/osgppu)
library. 

However I have to check if the error doesn't appear on
my machine at home, because there I have updated the
drivers already (oh, this GPU-fan bug makes me crazy
;-) ).

Cheers,
Art

> Hi Art,
> 
> Per the spec
>
http://www.opengl.org/registry/specs/EXT/geometry_shader4.txt
> 
> 
> - the default value of GEOMETRY_VERTICES_OUT_EXT is
> 0.
> 
> - error INVALID_VALUE is generated by
> ProgramParameteriEXT if
> GEOMETRY_VERTICES_OUT_EXT is negative or exceeds
> MAX_GEOMETRY_OUTPUT_VERTICES_EXT.
> 
> If the error happening due to ProgramParameteriEXT
> then I'd say it's a
> driver bug.
> 
> Such an error is defined during link:
> <quote>
>     Linking will also
>     fail if the program object contains objects to
> form a geometry
> shader (see
>     section 2.16), but no objects to form a vertex
> shader or if the
> program
>     object contains objects to form a geometry
> shader, and the value of
>     GEOMETRY_VERTICES_OUT_EXT is zero.
> </quote>
> But that appears not to be your situation.
> 
> I've not experienced this error myself on Quadro FX
> 360M w/ ForceWare
> 101.19.  I'll be glad to run repro code if you can
> send.
> 
> But my guess is a driver update is in order.
> 
> Cheers
> -- mew
> 
> 
> 
> 
> > -----Original Message-----
> > From: osg-users-bounces at lists.openscenegraph.org
> [mailto:osg-users-
> > bounces at lists.openscenegraph.org] On Behalf Of Art
> Tevs
> > Sent: Friday, January 11, 2008 9:33 AM
> > To: OpenSceneGraph Users
> > Subject: [osg-users] Bug in GeometryShaders
> causing OpenGL Error
> > 
> > Hi!
> > 
> > After updating the osg version from the svn which
> do
> > include the geometry shader implementation I got
> > always an OpenGL invalid value error. (nVidia
> driver
> > 100.14.1)
> > 
> > The error is located in the Program.cpp in the
> line
> > 2667:
> > 
> > _extensions->glProgramParameteri(
> _glProgramHandle,
> > GL_GEOMETRY_VERTICES_OUT_EXT,
> > _program->_geometryVerticesOut );
> > 
> > Here the default value of _geometryVerticesOut is
> set
> > to 0, which do cause problems on my system.
> Changing
> > the default value to 1 in the constructor line
> 2319:
> > 
> > Program::Program() :
> >     _geometryVerticesOut(1),
> > _geometryInputType(GL_TRIANGLES),
> >     _geometryOutputType(GL_TRIANGLE_STRIP)
> > {
> > }
> > 
> > 
> > doesn't break any rendering (I do not use geometry
> > shaders at now) and removes the invalid value
> error.
> > 
> > Could somebody please chek this.
> > 
> > Best regards,
> > Art
> 
> 
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>
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