Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073)

Hi Dr. Hoffmann,

Excellent find in the specification! The SVG Working Group discussed this issue 
and we concluded that we should add wording that warns authors of the problem.

As a result I was given ACTION-2284 [1] to add the wording to the specification. 
The new wording can be found in "The TransformRef value" [2] section of the 
specification.

Please advise the SVG Working Group if you have any further comments or feedback 
regarding this issue.

Kind Regards,

[1] http://www.w3.org/Graphics/SVG/WG/track/actions/2284
[2] http://dev.w3.org/SVG/profiles/1.2T/publish/coords.html#transform-ref

Doug Schepers wrote:
> Hi, Dr. Olaf-
> 
> Thanks for your comment.  We will discuss it and get back to you soon.
> 
> Regards-
> -Doug
> 
> Dr. Olaf Hoffmann wrote (on 9/27/08 11:53 AM):
>> Hello SVG WG,
>>
>> the section 7.7 about constrained transformations mentions
>> several times the inverse of the CTM. Obviously this does
>> not always exist (if the determinant is zero).
>> Is it really intended, that this inverse matrix is used by 
>> implementations to get the desired effect or is it expected, 
>> that the effect is gained with other methods (what should be 
>> always possible even without using the not always existing 
>> inverse matrix, because the document contains much more 
>> information about the transformations than only the CTM)?
>>
>> But if it is really expected, that the inverse matrix
>> is used, what is the expected behaviour, if it does not exist,
>> for example for a short time within an animation or due to
>> some tricky things using the vector-effect non-scaling-stroke.
>> To mention this would be important especially for authors,
>> because then they have to compute and avoid such situations.
>> If another method is used, they do not really have to care.
>>
>>
>> Olaf
>>
>>
>>
> 
> 

Received on Friday, 10 October 2008 07:19:58 UTC