Performer and GL blinking prob

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Dorrie Hall (dorrie++at++beamish.mit.edu)
Wed, 19 Jul 1995 21:01:08 -0400

>I have a Performer application and I call a GL program from the draw process
>which draws overlay graphics on the Performer scene. It works good except the
>GL overlay graphics blink pretty bad. Could anyone identify a cause for
>this?

Hi Stephanie,

   I used to use overlay mode but based on some very helpful
information posted by Sharon Rose Clay which said that
switching to overlay was a costly operation I draw things
I want on top of the scene by "turning off" the z buffering
in the postdraw callback.

something like this:

   
   /* draw in the same x,y coords as scene */
    pfPushState();
    pfBasicState();

    pfDisable(PFEN_TEXTURE);
    pfDisable(PFEN_LIGHTING);
    pfDisable(PFEN_FOG);
    zfunction(ZF_ALWAYS);

    zwritemask(0x000000);

   /* draw labels or instruments */

   zwritemask(0xFFFFFF);
   pfPopState();

   If you are adding code to pickfly it maybe clearing the
overlay planes and causing the "blinking".

        Dorrie

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