[Public WebGL] questions about vertexAttribPointer / getVertexAttrib offsets

Gregg Tavares (勤) [email protected]
Mon Apr 23 12:45:01 PDT 2012


On Mon, Apr 23, 2012 at 12:06 PM, Boris Zbarsky <[email protected]> wrote:

> On 4/23/12 2:43 PM, Gregg Tavares (勤) wrote:
>
>> There's at least one negative offset test in
>> https://cvs.khronos.org/svn/**repos/registry/trunk/public/**
>> webgl/sdk/tests/conformance/**more/functions/**
>> vertexAttribPointerBadArgs.**html<https://cvs.khronos.org/svn/repos/registry/trunk/public/webgl/sdk/tests/conformance/more/functions/vertexAttribPointerBadArgs.html>
>>
>
> Doesn't that call fail per current spec because the offset (-1) is not a
> multiple of sizeof(float), independently of what negative offset handling
> looks like?  My Gecko build with the negative offset check in
> vertexAttribPointer removed passes this test, precisely for that reason:
>
>  VertexAttribPointer: byteOffset doesn't satisfy the alignment requirement
> of given type @ https://cvs.khronos.org/svn/**repos/registry/trunk/public/
> **webgl/sdk/tests/conformance/**more/util.js:965<https://cvs.khronos.org/svn/repos/registry/trunk/public/webgl/sdk/tests/conformance/more/util.js:965>
>
> -Boris
>

To be clear

1) AFAICT OpenGL does not allow negative offsets

2) WebGL should not allow them either.

So,

a) we should update the WebGL spec to make it clear negative offsets
generate INVALID_VALUE

and

b) we should update the conformance tests to test that case.

Agree?
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