Re: Identifying pixels

Athanasios Mantes wrote: 
Hi all,

I have a 3d scene with various objects rendered, and I'm trying to do the following: render a small tooltip that shows the distance of the camera to the point in 3d space that corresponds to the pixel the mouse points. I know that I have to get the z buffer for the pixel, use gluUnproject etc, but my problem is this: since moving the mouse doesn't cause the scene to re-render, I can't get the z buffer value for an arbitrary pixel, without rendering the scene first, and reading the depth component pixel value for the specific pixel. Of course, rendering the scene for every mouse move is not desired (as many of you pointed out in a previous post), but I don't see another way, and reading the depth value for all pixels, is slow.


Why can't you read the depth buffer more than once
(ie. without re-rendering)?

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