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Re: [Public WebGL] Adding internalformat param to all texImage2d variants



On Thu, May 20, 2010 at 17:30, Tim Johansson <timj@opera.com> wrote:
> On 2010-05-20 11:14, Cedric Vivier wrote:
>> ES section 4.4.7 second paragraph defines conversion takes place.
>> The conversions rule used are once again the same as in the conversion
>> table proposed, ie. ES table 3.12, GL tables 3.11 and 3.20 (or 3.20/23
>> depending spec version).
>
> So if you create a texture from an Image object, then bind it to and FBO and
> render full RGBA data to it the result will be different depending on the
> internal format?
> If the original image was RGB the alpha channel could be lost when I render
> to it, but it might not depending on the implementation.

Good point :)
But is this really an issue ?
I mean, this could happen only if the developer lets the
implementation decide the internalformat of a texture
(0/NONE/DONT_CARE) that he will be using for render-to-texture usage.
It implies the developer does not mind potential loss of information
on the render-to-texture result (meaning here, that the developer does
not need/want alpha).

We could either consider that it is the responsibility of the
developer who performs render-to-texture to make sure the target
texture has been loaded with intended format, or - perhaps - we could
generate an error when attempting to FBO attach a WebGLTexture that
has been loaded with an internalformat of implementation's choosing,
to force this to be explicit. What do you think ?


Regards,
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