Re: background texture using glDrawPixels

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From: Angus Dorbie (dorbie++at++sgi.com)
Date: 10/12/2000 22:34:30

No clear in pfDraw, you are expected to clear if you have a draw
callback on a channel.

You may not need to clear if you set your depth test to always when you
draw the image.
Same thing goes for stencil test and write when drawing.

In general your code should work I as far as I can tell. Are you sure
you are double buffered?

Cheers,Angus.

Yoram Shahak wrote:
>
> Hi,
>
> I am trying to implement background texturing using glDrawPixels in my
> draw call back.
> my code looks something like this :
>
> void drawCallBack(pfChannel *chan, void *data)
> {
> preDraw(chan, data);
> pfDraw();
> }
>
> void preDraw()
> {
> chan->clear();
> glClearStencil(0x0);
> glClear(GL_STENCIL_BUFFER_BIT);
>
> pfVec3 farPlaneLL, dummy;
> chan->getFar(farPlaneLL, dummy, dummy, dummy);
>
> glRasterPos3f(farPlaneLL[0], farPlaeLL[1], farPlaneLL[2]);
> glDrawPixels(winWidth, winHeight, imageFormat,GL_UNSIGNED_INT,
> imageBuffer);
>
> }
>
> As a result I get the background image flickering if at all seen.
> Does performer clear the gl buffer in pfDraw ?
> Am I going totally the wrong way about implementing this ?
>
> Please help .
> Thanx.
>
> :o)
>
> Yoram Shahak
> DreamTeam ltd.
>
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