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Re: [Public WebGL] Feature proposal for TypedArrays



On Mon, May 10, 2010 at 10:57 AM, Vladimir Vukicevic
<vladimir@mozilla.com> wrote:
> On 5/10/2010 9:49 AM, Chris Marrin wrote:
>>
>> But fp32 and fp64 are supported in compilers and hardware FPUs. I don't
>> know of any CPU's that support fp16 natively. So full support would require
>> conversion to and from a support FP format. I don't think it's worth doing
>> that at this point.
>
> This is the part that worries me the most about the proposal, but even if we
> implemented fp16 support in software, the typical usage could be to do math
> as fp32 and then convert to fp16 before uploading to the video card for
> memory savings.  That would argue for having a fp16 type, but cautioning
> developers to not actually do math with it, which is a little scary --
> someone invariably will.  However, if the use case is mainly for
> pre-computed data, it can already be stored and transmitted as a raw buffer
> (and if light manipulation is needed, an unsigned short array would provide
> access to the individual fp16 elements).

I think it would be a good idea to eventually support the "half" data
type, but currently there are no planned WebGL extensions that would
use it. The additional cost is significantly higher than for the other
existing data types because most CPUs do not support this format
natively.

I think that we should add this as a to-do item, but not add it to the
TypedArray or WebGL specifications at the current time. There is
already too much work that needs to be done to stabilize the
specification for version 1.0.

-Ken

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