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Re: [Public WebGL] Additional texture/vertex formats



You could still upload Float16 data as an opaque byte array, which would make it useful for some model or texture formats. I would imagine that the image based lighting mentioned earlier would be precomputed, and as such could be pulled from the server directly with no JS transformation.Â

As such I don't see a big need to mangle Float32 data into a lower precision on the fly. It sounds convenient, but I have a hard time imagining that it would end up as anything but a performance pitfall for uninformed devs.

--Brandon

On Mon, Jul 23, 2012 at 11:37 AM, 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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