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Re: [Public WebGL] Move flipY and asPremultipliedAlpha parameters out of DOM helpers



On Wed, May 19, 2010 at 5:38 PM, Cedric Vivier <cedricv@neonux.com> wrote:
> On Thu, May 20, 2010 at 08:28, Kenneth Russell <kbr@google.com> wrote:
>> This proposal is not implementable. The data conversion and
>> manipulation performed by these flags must be done when the texture's
>> data is uploaded. It is simply not possible to configure them
>> dynamically.
>
> Hmm the proposal does not imply to configure them dynamically.
> It says the manipulation takes place at update (texImage2D usage),
> exactly like GL's GENERATE_MIPMAP tex parameter.
>
> Implementations of texImage2D that currently do :
>
> if (flipY)
>    performFlipY(...));
>
> Would do :
>
> if (currentlyBoundTexture && currentlyBoundTexture->flipY)
>    performFlipY(...);
>
>
> Or is there something I overlook here??

Changes to texture parameters take effect immediately. There are no
texture parameters which affect the behavior of later calls (for
example to glTexImage2D) but whose changes are not otherwise seen.
This means that changing this texture parameter would have to affect
the texture object already on the graphics card. This will kill
performance at best and is unimplementable at worst.

-Ken

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