[Public WebGL] Oversight in bufferData and bufferSubData specification

Gregg Tavares (wrk) [email protected]
Fri May 20 20:17:22 PDT 2011


Why does it matter?

in real GL, bufferData and bufferSubData just take void* and a length so it
seems like any ArrayBufferView should be valid.

I can do this now

gl.bufferData(gl.ARRAY_BUFFER, someUint8BufferView);   // upload bytes,
gl.vertexAttribPointer(0, 3, gl.FLOAT, ...)   // use as floats

or visa versa

gl.bufferData(gl.ARRAY_BUFFER, someFloat32BufferView);   // upload floats,
gl.vertexAttribPointer(0, 3, gl.BYTE, ...)   // use as bytes

so why does it matter that I can upload a Float64Array? What I upload and
how I used it are not related in WebGL




On Fri, May 20, 2011 at 6:50 PM, Kenneth Russell <[email protected]> wrote:

>
> In the bufferData and bufferSubData variants taking ArrayBufferView,
> we failed to specify what happens if a Float64Array is passed.
> http://www.khronos.org/registry/webgl/specs/latest/#5.12 mentions that
> Float64Array can not be used with WebGL, but does not specify what
> happens if an attempt is made.
>
> The other entry points which take ArrayBufferView (readPixels,
> texImage2D, texSubImage2D) also take a type enum, and generate
> INVALID_OPERATION if that type enum and the type of the
> ArrayBufferView do not match. Therefore, these entry points will
> already generate INVALID_OPERATION in this case.
>
> Options seem to be:
>
>  1. Generate an INVALID_VALUE OpenGL error if a Float64Array is passed.
>  2. Change the IDL in the WebGL spec to explicitly enumerate all of
> the ArrayBufferView subclasses accepted for bufferData, bufferSubData,
> readPixels, texImage2D, and texSubImage2D.
>
> Firefox 4 currently has a bug where it silently accepts Float64Arrays
> for bufferData, so some change is definitely needed.
>
> I would probably recommend (2) despite the slight explosion in the IDL
> because it's most compatible with the intent of the spec. This would
> mean that an exception would be raised per the Web IDL spec.
>
> -Ken
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