[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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



The WebGL WG discussed this topic in a recent concall, and the
consensus was to ask about adding an OpenGL ES 2.0 extension
specifying floating-point framebuffer support. Unfortunately, it
doesn't look like there is interest from the OpenGL ES working group
in doing so.

There seems to be agreement among the WebGL WG members that enabling
render-to-fp-texture functionality, where it can be supported, is
crucial. Further, there's at least one ES 2.0 chipset that supports
fp16 renderbuffers. Therefore, I've updated the WebGL extension
registry's exposure of OES_texture_float and OES_texture_half_float
([1], [2]) to indicate that the WebGL versions of these extensions
optionally allow these textures to be used as the color attachments to
FBOs.

I think that any changes related to reading back of FLOAT pixels via
readPixels should wait for a future revision of the WebGL spec.

Please post any comments to the list. Thanks.

[1] http://www.khronos.org/registry/webgl/extensions/OES_texture_float/
[2] http://www.khronos.org/registry/webgl/extensions/OES_texture_half_float/

-Ken

On Thu, Sep 1, 2011 at 3:40 AM, Ribble, Maurice <mribble@qualcomm.com> wrote:
> In OpenGL ES there is an OES_rgb8_rgba8 extension that would allow you to
> render to 888 and 8888 formats.  It might be reasonable to require this
> extension for webGL implementations.  All our Adreno 2xx hardware supports
> this extension.
>
>
>
> I know this isn’t the best written extension and more recent OES extension
> are going through a more extensive review process to ensure higher quality.
> That said this extension is used by many developers on our hardware and it
> seems to be working the way they expect it to.
>
>
>
> -Maurice
>
>
>
> From: Gregg Tavares (wrk) [mailto:gman@google.com]
> Sent: Thursday, September 01, 2011 12:42 AM
> To: Mark Callow
> Cc: David Sheets; Kenneth Russell; Benoit Jacob; Ribble, Maurice; Christian
> Junker; public_webgl@khronos.org
>
> Subject: Re: [Public WebGL] readPixles() can't access float values
> (OES_texture_float interaction)
>
>
>
> That means we need an extension for RGB8 and RGBA8 as well?
>
>
>
> And following the WebGL model of no extension feature is exposed to WebGL
> unless you call getExtension this means breaking every WebGL program that
> uses FBOs currently because I can pretty much guarantee, none of them ask
> for 565, 4444 or 5551 textures for their FBO textures. All of them are
> making 888 or 8888.
>
>
>
>
>
>
>
> On Thu, Sep 1, 2011 at 12:21 PM, Mark Callow <callow_mark@hicorp.co.jp>
> wrote:
>
> As I pointed out before, the core spec. does provide a guarantee. It says
> that the RGB565, RGBA4444 & RGBA5551 internal formats are color renderable
> and that NO other format is color renderable. Regardless of the confusion
> about how an application can guarantee to create a texture with one of these
> internal formats, it is very clear that an FP texture is not going to have
> one of these internal formats and will therefore not be color renderable.
>
> An extension is required in OpenGL ES and in WebGL.
>
> Regards
>
> -Mark
>
> On 2011/08/31 21:11, Gregg Tavares (wrk) wrote:
>
> As far as I recall, OpenGL ES 2.0 makes no promises about what types of
> textures can be bound to frame buffers. The only way to know is to bind one
> and then call glCheckFramebufferStatus.
>
>
>
> So, do we need a specific extension to enable rendering to floating point
> textures or is the current situation good enough?
>
>

-----------------------------------------------------------
You are currently subscribed to public_webgl@khronos.org.
To unsubscribe, send an email to majordomo@khronos.org with
the following command in the body of your email:
unsubscribe public_webgl
-----------------------------------------------------------