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



On 18 May 2010, at 18:21, Chris Marrin wrote:

> 
> On May 16, 2010, at 1:11 PM, Johannes Behr wrote:
> 
>> HI,
>> 
>>>> 
>>>> This can be easily done during runtime as part of your standard-shader
>>>> but we just have to know it upfront.
>>> 
>>> Yes, this is the original discussion. But you only need to know the original format because that's how X3D defines it today.
>> 
>> Right. We only need to know. Can be RGB or RGBA or anything we understand at the end. 
>> 
>>> In fact X3D is deficient in that, if you have an RGB image and want to use it as an alpha channel you can't.
>> 
>> Correct for the standard lighting model. But you can use the shader component and your are free to do whatever you want. 
>> 
>>> X3D has no property to indicate that the image should be stored in texture memory in the requested format. 
>>> 
>>> My proposal would change the rules of the X3D ImageTexture. You'd have to add a format property, where you specify what format you want the texture to be. There might be some incompatibilities in a small amount of X3D content, but I think you'd have a better ImageTexture spec.
>> 
>> I don't agree. Putting a extra "format" parameter to the ImageTexture spec would not lead to a better ImageTexture interface:
>> 
>> - What should this format be if you use the ImageTexture e.g. as shader property ?
>> - Source of confusion if the image and format do not match. What should happen if somebody changes the url during runtime ?
>> - You can not reuse the ImageTexture with a different format.
> 
> If I have an image that is 2 channels (LA) and my shader expects it to be RGB, I won't get reasonable results, right? If so I don't think having the format automatically set is very useful. 

Used with the standard material setup or explicit shader ?

regards
johannes

> 
> -----
> ~Chris
> cmarrin@apple.com
> 
> 
> 
> 

--
Dr. Johannes Behr
Leiter Projektbereich VR

Fraunhofer-Institut für Graphische Datenverarbeitung IGD
Fraunhoferstr. 5  |  64283 Darmstadt  |  Germany
Tel +49 6151 155-510  |  Fax +49 6151 155-196
johannes.behr@igd.fraunhofer.de  |  www.igd.fraunhofer.de


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