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

Florian Bösch [email protected]
Mon Sep 19 11:39:53 PDT 2011

On Mon, Sep 19, 2011 at 8:14 PM, Chris Marrin <[email protected]> wrote:

> Are you saying an author should discover whether or not it's possible to
> create a FP FBO by trying and if the FBO is incomplete after the attempt,
> that's an indication that it's not supported? I don't think that has
> precedence. Seems like it's much better to use the extension mechanism. If
> the attempt to enable the extension fails, then it's not a feature that can
> be used.
Yes it's a bit messy. But the
http://www.opengl.org/registry/specs/ARB/texture_float.txt makes no
stipulation if framebuffers have to support it or not.
Likewise http://www.opengl.org/registry/specs/ARB/framebuffer_object.txt does
not make any such guarantee, however it does discuss various use cases with
floating point attached buffers, including color.

In my (limited, desktop oriented) practice I have not yet seen a device
which supports floating point textures and FBOs, but cannot handle attaching
a floating point texture to an FBO. So regardless of the intent of webgl,
OpenGL does not support the query you'd like to execute. The only way to
execute your desired "can this thing support floating point attachments" is
to try it out, unless the extension registry is updated with just such an

If you'd like to provide the "try it out" semantic via some webgl extension,
or weather you'll leave it up to the user is of no significance of me. As
long as I can still attach floating point textures to an FBO in some manner.
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