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Re: [Public WebGL] WEBGL_depth_texture unspecified case: sampling from an uninitialized depth texture



On 13-09-26 03:05 PM, Benoit Jacob wrote:
> Hi,
>
> WEBGL_depth_texture introduces a basic possibility that does not exist
> in the core WebGL spec: the possibility of an uninitialized texture.
>
> While uninitialized renderbuffers are only an implementation detail that
> doesn't have any existence at the level of the WebGL spec, uninitialized
> textures are different because they can be sampled from.
>
> The question is what should the spec mandate implementations to do when
> executing code like this:
>
>    CreateAndTexImage2DSomeUninitializedDepthTexture();
>    SetUpRenderingStateSamplingFromThatTexture();
>    Draw();
>
>
> It's not technically an INVALID_FRAMEBUFFER_OPERATION since the
> uninitialized texture here is one we are sampling from, not one we are
> rendering to. So should that be an INVALID_OPERATION?

Oh, I suppose that the right thing to do here is to sample it as
RGBA(0,0,0,0) pixels i.e. treat it as an incomplete texture. With (UA
detail) a good JS warning to let people know why their textures are not
working.

OK to spec it that way?

 Benoit

>
> Note: I'm running into this while implementing support for
> WEBGL_depth_texture on clients supporting only ANGLE_depth_texture. I
> understand that Chrome already supports that. I would like to know what
> is Chrome's current behavior there.
>
> Thanks,
> Benoit
>
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