[x3d-public] text minor alignment

[Andreas Plesch]

Hello Roy,

thanks for reviewing this issue. In the mean time I had opportunity to view
the scene with freeWrl and InstantPlayer. Both render the scene as
expected, eg. with the first line above the x-axis while its baseline just
touches it. So I think something was a bit off when the snapshot on the
archive web site was generated.

Andreas


On Wed, Sep 9, 2015 at 8:14 AM, Roy Walmsley <roy.walmsley at ntlworld.com>
wrote:

> Andreas,
>
>
>
> I have reviewed your comments below and find that I am in agreement with
> you.
>
>
>
> You are correct in saying that the default for the /justify/ field is
> [“BEGIN” “FIRST”]. This is quite clearly stated in 15.2.2.3 of the 19775-1
> specification.
>
>
>
> Then, when /horizontal/ is TRUE and /topToBottom/ is TRUE, which both are
> by default, Table 15.4 in the 19775-1 specification states that when the
> minor alignment is “FIRST” the baseline of the first line shall be aligned
> with the origin.
>
>
>
> The inevitable conclusion is that the figure displaying the NIST
> Conformance for the default field settings is incorrect. I will raise this
> issue for discussion at the next available opportunity. Please keep us
> informed of any further findings.
>
>
>
> Great catch. Thank you.
>
>
>
> Regards,
>
>
>
> Roy
>
>
>
> *From:* x3d-public [mailto:x3d-public-bounces at web3d.org] *On Behalf Of *Andreas
> Plesch
> *Sent:* 09 September 2015 00:03
> *To:* X3D Graphics public mailing list
> *Subject:* [x3d-public] text minor alignment
>
>
>
> I am trying to produce more correct text alignment with x3dom, and want to
> clarify my understanding of the minor alignment, the second value of the
> justify MFString field of the FontStyle node. My main reference is table
> 15.6 in the spec. at
>
>
>
>
> http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/text.html#t-horizontalTRUE
>
>
>
> where the different colors of the origin symbols signify minor alignment
> types.
>
>
>
> In particular, I understand that 'FIRST' (black) is different from 'BEGIN'
> (red) in that 'FIRST' will align the base of the first line with Y=0
> (x-axis) while 'BEGIN' will align the top of the first line with Y=0 (in
> the topToBottom case). I also understand that 'FIRST' is the default for
> minor alignment. Is this correct ?
>
>
>
> [I am not quite sure why 'FIRST' is the default since it seems to require
> to take into account the size of the used font when accurately positioning
> text in a scene. Also, the size of a typeface referred to in its name
> refers to a box a bit larger than the distance from the lowest point of any
> glyph (say y) to the highest point (say $). This makes it generally hard to
> determine where the baseline of a font is just based on its nominal size.]
>
>
>
> If my understanding is correct, the rendering of a default text node in a
> scene such as
>
>
>
>
> http://www.web3d.org/x3d/content/examples/ConformanceNist/Appearance/FontStyle/_pages/page01.html
>
>
>
> should more or less look like this:
>
>
>
> http://andreasplesch.github.io/x3dom/x3dom_text/alignment.xhtml
>
>
>
> eg., the first line should be above the x-axis (green line).
>
>
>
> However, the snapshot provided with scene in the web3d archive here
>
>
>
>
> http://www.web3d.org/x3d/content/examples/ConformanceNist/Appearance/FontStyle/_viewpoints/default.x3d._VP_Test_default_FontStyle_rendering.png
>
>
>
> shows the first line underneath the x-axis, not above. This is where I am
> looking for clarification. The x3d browser used for the snapshot (xj3d?)
> may or may not faithfully adhere to the spec.
>
>
>
> I may also try other browsers with the scene to see how they interprete
> the default positioning of a text node.
>
>
>
> Thanks for any input,
>
>
>
> Andreas
>
>
>
>
> --
>
> Andreas Plesch
> 39 Barbara Rd.
> Waltham, MA 02453
>



-- 
Andreas Plesch
39 Barbara Rd.
Waltham, MA 02453
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