Re: Line Flicker

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Nicolas Gauvin (nicolas++at++cae.ca)
Thu, 18 Sep 1997 15:32:23 -0400

On Sep 17, 10:28am, SCOTT OFRIEL wrote:
> Subject: Line Flicker
> Subject: Time: 10:11 AM
> OFFICE MEMO Line Flicker Date: 9/17/97
>
> Hello:
>
> We get line flicker. We have a grid laid down on the ground of an earthSky
> scene. The grid lines flicker as the eye point moves. For example, when the
> user selects the F-18 target as the viewpoint, The lines flicker. The line
> flicker appears to be a function of zoom which can be easily modified by the
> user. The farther out the zoom the more flicker.
>
> Any suggestions please?

Your grid is probably coplanar with the ground polygon drawn by Performer
and you get flicker resulting from z fighting. You could lower the ground
polygon using the PFES_GRND_HT attribute of the pfEarthSky or draw your
grid yourself with depth testing disabled in a draw callback, just after
 clearing the channel and before calling pfDraw. You need to re-enable
depth testing before calling pfDraw.

-- 
Nicolas Gauvin              CAE Electronics Ltd., 8585 Cote De Liesse
3D Graphics Software        Saint-Laurent, Quebec, Canada, H4L-4X4
nicolas++at++cae.ca              Tel: (514) 341-2000 x2275, Fax: (514) 340-5496 
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