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

Glenn Maynard [email protected]
Tue Sep 13 16:53:13 PDT 2011

On Tue, Sep 13, 2011 at 7:22 PM, Mark Callow <[email protected]>wrote:

>  Doing this goes against the long standing principle of uniformity across
> implementations.
First off, the much longer-standing principle of Web APIs is that once an
interface is released to the public and used in the wild, it's there to
stay; breaking APIs should only be done for very serious reasons, usually
security-related.  APIs being released, used by developers, and then removed
out from under them destroys developer confidence in the platform.

Second, there's no "principle of uniformity" in WebGL.  If there was, the
dozen or so MAX_ constants wouldn't be there--all implementations would have
the same maximum texture size, TUs and so on, with no possibility for them
ever being increased.  There would be no extension mechanism at all.  These
mechanisms exist precisely because the hardware underneath implementations
has varying capabilities, and it would be disastrous to limit WebGL to the
lowest-common-denominator of hardware.

It's acceptable, and desirable, to limit the variation exposed to scripts in
the absence of explicit opt-ins, to minimize *accidental* dependancies on
features not available on low-end hardware.  (I think this should even have
been done for eg. MAX_TEXTURE_SIZE and so on: have a baseline profile with
MAX_TEXTURE_SIZE = 2048 or so, for example, with larger textures being
rejected unless an eg. WEBGL_DESKTOP_PROFILE_2011 extension is loaded to
explicitly indicate that you're raising the profile required by your
program.)  It's not acceptable, however, to prevent people from writing
games and applications targetting desktop hardware because you don't want
people creating anything that doesn't work on your phone.

>  The facts of the matter are that there is NO mobile GPU design
This is WebGL, not WebMobileOnlyGL.  Limiting its usability so drastically
would severely limit WebGL's chances of gaining broad acceptance by

Glenn Maynard
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