[GEM-dev] [ pd-gem-Feature Requests-2612731 ] glsl_geometry

IOhannes m zmölnig zmoelnig at iem.at
Thu Apr 23 17:54:50 CEST 2009


cyrille henry wrote:
> ok, thanks
> it now compiles.
> 
> but i still have the same problem trying to run the shader : i've got 
> invalid operation message at every frame.

this you get when the geometry you work on (e.g. generated by [square]) 
does not match the geometry specified for the geometry-shader (as set in 
[glsl_program])

the default in/out geometry is GL_TRIANGLES (in) and GL_TRIANGLE_STRIP 
(out)m which should work with "fill"ed [square].
if you change the [square] to "line", you have to change the in/out to 
GL_LINES (and/or GL_LINE_STRIP); do so by sending a
[geometry_type GL_LINES GL_LINE_STRIP(
to [glsl_program] (!) before linking the shaders.


> 
> could you post the patch that worked?

i used (among others) your patch, and it worked (iirc) out-of-the box 
with [cube], but not with [curve] (though it should be enough to change 
the in/out geometry as mentioned above)

> or make it an official Gem example?

yes, but the shader provided is so extraordinarily boring that i wanted 
to wait for a nice one from you...:-)

> or have you already done it?

nope.
i'm off that machine now, i will check in a known-to-work example when 
i'm back at it...


mfg.sd
IOhannes




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