ISSUE-2073: inverse and constrained transformations

constrained transformations

inverse and constrained transformations

State:

CLOSED

Product:

SVG 1.2 Tiny: Last Call

Raised by:

Doug Schepers

Opened on:

2008-09-28

Description:

Dr. Olaf Hoffmann
<http://lists.w3.org/Archives/Public/www-svg/2008Sep/0123.html>:
[[
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.
]]

Related Actions Items:

• ACTION-2284 on Anthony Grasso to Put a warning in the spec regarding non-invertable matrices when animating transforms. Email back Dr Hoffmann - due 2008-10-16, closed
• ACTION-2336 on Cameron McCormack to Improve wording on non-invertible CTMs - due 2008-10-31, closed

Related emails:

1. Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073) (from Dr.O.Hoffmann@gmx.de on 2008-11-02)
2. Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073) (from cam@mcc.id.au on 2008-11-02)
3. SVG/profiles/1.2T/master coords.html,1.117,1.118 (from cvsmail@w3.org on 2008-11-02)
4. Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073) (from Dr.O.Hoffmann@gmx.de on 2008-10-30)
5. SVG/profiles/1.2T doc-svgt12.html,NONE,1.1 (from cvsmail@w3.org on 2008-10-28)
6. Minutes, 24 Oct 2008 SVG f2f (from chris@w3.org on 2008-10-27)
7. Re: Wording for non-invertable CTMs with ref() (for ISSUE-2073) (from cam@mcc.id.au on 2008-10-25)
8. SVG/profiles/1.2T/master coords.html,1.113,1.114 (from cvsmail@w3.org on 2008-10-25)
9. Re: Wording for non-invertable CTMs with ref() (for ISSUE-2073) (from cam@mcc.id.au on 2008-10-24)
10. Re: Wording for non-invertable CTMs with ref() (for ISSUE-2073) (from chris@w3.org on 2008-10-24)
11. Wording for non-invertable CTMs with ref() (for ISSUE-2073) (from cam@mcc.id.au on 2008-10-22)
12. Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073) (from Dr.O.Hoffmann@gmx.de on 2008-10-15)
13. Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073) (from anthony.grasso@cisra.canon.com.au on 2008-10-15)
14. SVG/profiles/1.2T/master coords.html,1.99,1.100 (from cvsmail@w3.org on 2008-10-15)
15. Minutes, SVG telcon Tuesday 14 October 2008 (from anthony.grasso@cisra.canon.com.au on 2008-10-14)
16. Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073) (from Dr.O.Hoffmann@gmx.de on 2008-10-13)
17. SVG/profiles/1.2T/publish animate.html,1.97,1.98 coords.html,1.88,1.89 single-page.html,1.101,1.102 (from cvsmail@w3.org on 2008-10-13)
18. Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073) (from anthony.grasso@cisra.canon.com.au on 2008-10-13)
19. Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073) (from schepers@w3.org on 2008-10-12)
20. Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073) (from Dr.O.Hoffmann@gmx.de on 2008-10-11)
21. Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073) (from anthony.grasso@cisra.canon.com.au on 2008-10-10)
22. SVG/profiles/1.2T/master coords.html,1.97,1.98 (from cvsmail@w3.org on 2008-10-10)
23. Minutes, SVG telcon Thursday 9 October 2008 (from anthony.grasso@cisra.canon.com.au on 2008-10-09)
24. ISSUE-2073 (constrained transformations): inverse and constrained transformations [Last Call: SVG 1.2 Tiny ] (from sysbot+tracker@w3.org on 2008-09-28)
25. Re: [1.2T-LC] inverse and constrained transformations (ISSUE-2073) (from schepers@w3.org on 2008-09-27)

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