[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Public WebGL] vertexAttribPointer conformance test



I've seen both variations used to good effect in desktop OpenGL and
Direct3D - and afaik, both are legal. 

The first one (where the attributes overlap each other) does have a few
uses - but they are pretty bizarre and I don't think many people would
be too upset if it wasn't allowed.

The second (where the data has gaps) is essential to a couple of
strategies for handling large area terrain skins and some
level-of-detail mechanisms.

Loss of the first isn't disasterous if it can't be implemented - but
loss of the second would be very bad news.

  -- Steve

On 01/05/2011 06:50 PM, Vladimir Vukicevic wrote:
> I think some of these changes are wrong -- I agree that we should disallow (and I believe we already do and check for):
>
>   size = 3, type = FLOAT, stride = 2
>
> but I do not think that we should disallow
>
>   size = 3, type = FLOAT, stride = 4
>
> which the test currently does... the result here is perfectly valid, from my reading of the spec.
>
>      - Vlad
>
> ----- Original Message -----
>   
>> So I updated the test to test lots of combinations (checked in)
>>
>>
>> That brings up more questions about the restrictions added in section
>> 6.3
>>
>>
>> 1st) "why the restrictions"
>>
>>
>>
>>
>> Is there some situation we are trying to prevent that we need to
>> prevent?
>>
>>
>> 2nd) "why not more restrictions"
>>
>>
>> As currently specified it's possible to set size = 4, type = byte,
>> stride = 1. So as input to the shader you'll get
>>
>>
>> vec4 (element0,element1,element2,element3)
>> vec4 (element1,element2,element3,element4)
>> vec4 (element2,element3,element4,element5)
>>
>>
>> ...
>>
>> 3rd) "why INVALID_OPERATION"
>>
>>
>>
>>
>> wouldn't INVALID_VALUE be more appropriate?
>>     
> -----------------------------------------------------------
> You are currently subscribed to public_webgl@khronos.org.
> To unsubscribe, send an email to majordomo@khronos.org with
> the following command in the body of your email:
>
>   

-----------------------------------------------------------
You are currently subscribed to public_webgl@khronos.org.
To unsubscribe, send an email to majordomo@khronos.org with
the following command in the body of your email: