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Wireframe Overlay - glPolygonOffset

Started by Tommato Aug 7, 2014 at 10:02 AM 0 replies 4.1k views

Original Post

Aug 7, 2014 at 10:02 AM

Hi All

I need to draw wireframe over solid object. As I've understood from google, glPolygonOffset is a standard solution for this - but I can't get it to work. With first argument negative it has effect - wireframe disappears. But my wireframe still "blinks" with any view change, no matter what values are passed to glPolygonOffset. I've also tried different draw order and wireframe drawn as lines - no luck. What am I doing wrong?

Thanks

Tommato

L. Spiro

1,026

L. Spiro

Aug 7, 2014 at 10:36 AM

If the wireframe comes from the came vertex data as the model then all you need to do is set the depth mode to GL_EQUAL and draw the wireframe.

Or you can always modify gl_FragDepth, setting it to a value slightly smaller than gl_FragCoord.z, such as gl_FragCoord.z - (1.0f / 16000000.0) (this takes experimentation as well).

Otherwise you need to experiment with ::glPolygonOffset().

L. Spiro

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