[Public WebGL] gl.sizeInBytes

Kenneth Russell [email protected]
Mon Jan 11 11:48:04 PST 2010


On Mon, Jan 11, 2010 at 10:37 AM, Chris Marrin <[email protected]> wrote:

>
> On Jan 10, 2010, at 11:44 PM, Patrick Baggett wrote:
>
> > It is hardly a matter of "does a GL implementation have 64-bit
> GL_FLOATs", but more of "the WebGL spec explicitly states the size of its
> types." -- the latter entirely shutting off the concept of "implementation
> dependent" sizes.
> >
> > Vlad's right, even if gl.sizeInBytes(GL_FLOAT) did return 8 (double
> prec.) there would be no way to efficiently/portably buffer the data.
>
>
> So then maybe it would be better to replace these with constants
> (ctx.FLOAT_SIZE, ctx.INT_SIZE, ctx.UNSIGNED_SHORT_SIZE), etc.?
>

I think we should leave sizeInBytes as a function rather than defining
constants. On a hypothetical platform which defined GLfloat as a double, the
WebGL implementation would be responsible for making WebGLFloatArray manage
double-precision rather than single-precision floating point numbers.

As we consider proposing broader use of these array-like types, we will have
to specify the exact size of the machine types they manage. However, the
mapping between e.g. WebGLFloatArray to e.g. FloatArray vs. DoubleArray
would need to be flexible.

-Ken
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