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RE: [Public WebGL] readPixles() can't access float values (OES_texture_float interaction)



They are only texturing and not for rendering, therefore readpixels does not make sense.

-Maurice

-----Original Message-----
From: owner-public_webgl@khronos.org [mailto:owner-public_webgl@khronos.org] On Behalf Of Benoit Jacob
Sent: Tuesday, August 30, 2011 1:26 PM
To: Christian Junker
Cc: public_webgl@khronos.org
Subject: Re: [Public WebGL] readPixles() can't access float values (OES_texture_float interaction)


As far as I can see, this question boils down to whether or not all 
OpenGL[ES] implementations which support float textures also support 
readPixels on them.

If they do support that, then I don't see why we shouldn't support that too.

If some of them don't support that, then there's no way that we'll be 
able to support that on top of them.

Does anyone know how widely this is supported?

Cheers,
Benoit



On 26/08/11 07:20 AM, Christian Junker wrote:
>
> Hi,
>
> Although floating point textures are supported through the
> "OES_texture_float" extension, it is currently not possible to read
> back the pixels from the framebuffer.
> Using readPixels() does only work für UNSIGNED_BYTE (as described in the spec).
> The specification of the extension
> (http://www.khronos.org/registry/gles/extensions/OES/OES_texture_float.txt)
> doesn't mention interaction with readPixels() at all.
>
> My question now is, is this an oversight or desired behavior? (or did
> I simply overlook something?)
>
> I think allowing readPixels() to play together with floating point
> textures would be a highly desireable feature, esp. for
> diagnosing/debugging and gpgpu.
>
>
> Short example:
>
> var pixels = new Float32Array(framebuffer.width * framebuffer.height * 4);
> gl.readPixels(0, 0, framebuffer.width, framebuffer.height, gl.RGBA,
> gl.FLOAT, pixels);
>
> results in "Warning: WebGL: ReadPixels: type: invalid enum value 0x1406"
>
>
> Rest Regards
> Christian
>
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