Re: [Public WebGL] Additional texture/vertex formats

[Jeff Russell <jeffdr@gmail.com>]

Oh, I responded too quickly. Yes, some type of typed array would be important to have (doing it through Uint16 for example), but I just meant it wouldn't be necessary to create a Float16 typed array just for this extension.

On Mon, Jul 23, 2012 at 2:41 PM, Jeff Russell <jeffdr@gmail.com> wrote:

Not a deal breaker. There is no "half" type in C either. One can just alias with Uint16 and some conversion functions I would guess if you really needed to manipulate the values in _javascript_. Mostly for IBL applications though you'd just be feeding bytes through from a file format without touching them.

On Mon, Jul 23, 2012 at 2:37 PM, Kenneth Russell <kbr@google.com> wrote:

Half float textures are spec'ed for WebGL in
http://www.khronos.org/registry/webgl/extensions/OES_texture_half_float/
. There's a big caveat currently that typed arrays can't be used to
upload data into them, since there's no Float16 typed array type (and
because it would be extremely inefficient, I do not foresee adding
one).

Is that restriction a deal killer? Would the spec need to be amended
to support e.g. uploading from a Float32Array, with appropriate
truncation of the mantissa and exponent bits, in order to be useful
for image based lighting?

-Ken

On Sun, Jul 22, 2012 at 6:49 PM, Mark Callow <callow_mark@hicorp.co.jp> wrote:
>
> On 21/07/2012 03:42, Jeff Russell wrote:
>
> The bandwidth/memory savings are the main reason one would use them over
> float, and that's a big one. Not sure if it's still the case but in the
> desktop GPU world texture filtering was once easier to come by with half
> float instead of full precision float textures.
>
> I know less about mobile GPUs, but I understand bandwidth is if anything
> even more of an issue there.
>
> Bandwidth is indeed even more of an issue on mobile and it will almost
> certainly be the case that filtering will be more available for half-float
> than float for the same reasons it was once "easier to come by" on desktop.
>
> Regards
>
> -Mark
>
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