OpenGL ES (1.0 and 2.0) does not offer a way to read the depth buffer. You
can fake it in 2.0 by using a custom shader to render the scene in an FBO.
Here's the fragment shader I've used in the past to achieve this:
// uniform float UNI_near;
// uniform float UNI_far;
void main() {
// Non-linear depth value
float z = gl_FragCoord.z;
// Near and far planes from the projection
float n = UNI_near;
float f = UNI_far;
// Linear depth value
z = (2.0 * n) / (f + n - z * (f - n));
gl_FragColor = vec4(z, z, z, 1.0);
}
On Mon, Nov 7, 2011 at 12:48 PM, Latimerius <[email protected]>wrote:
> On Mon, Nov 7, 2011 at 6:01 PM, saex <[email protected]> wrote:
> > Yes Latimerius, i think that i dont have to pass 0 as winZ parameter,
> > but i dont know how to get the Z value from the depth buffer. I'm
> > programming for Android 1.5 and openGL ES1, i didn't find a working
> > way to obtain winZ value on google after hours of searching :(
> >
> > Did you know how to do it?
>
> Actually, if you're stuck with GL ES 1.0, unfortunately I'm not aware
> of a way to read the depth buffer. I'm no expert on legacy GL ES
> though so you might want to consider asking on a GL ES forum -
> although there might not be a direct way to read the depth buffer
> under GL ES 1.0 someone could know a work-around.
>
> If you can't use GL to do the unprojection you can still compute it
> manually.
>
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Romain Guy
Android framework engineer
[email protected]
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