W3C home > Mailing lists > Public > www-style@w3.org > August 1997

Angle values for azimuth and elevation

From: T. V. Raman <raman@Adobe.COM>
Date: Mon, 4 Aug 1997 15:23:01 -0700
Message-Id: <199708042223.PAA26473@labrador>
To: Liam Quinn <liam@htmlhelp.com>
Cc: www-style@w3.org
Liam Quinn writes:
 > Next up on my ACSS hit list is angle values for azimuth and elevation.  
 > The azimuth property specifies that an angle value be given in the range -
 > 360deg <= x < 360deg.  First off, I don't see why -360deg should be
should be either 0 <= x <= 360
-180 <= x <= 180
in either case a total range of 360deg --720 degrees doesn't make sense.
 > included since it's equivalent to 0deg.  But more importantly, it's 
 > unclear to me whether other values, such as 370deg or 3.14rad (hmm, we 
 > need a way to say pi), are invalid, or if the UA should simply convert to 
 > the equivalent degree value in the range -360deg to 360deg.  (A UA
The UA should probably convert in the range [0,360]
You dont want to outlaw 370degress because you want to be able specify
  rendering rules in style sheets of the form
"increment azimuth by 15 degrees and render yourself"
to simulate something going around the user with each successive element
  moving 15 degrees along the circle.

 > conversion seems appropriate to me, FWIW.)
 > Similarly, the elevation property specifies an angle value in the range -
 > 90deg to 90deg.  Does this mean that 270deg is invalid?  Shouldn't this 
 > angle value be normalized to the range -90deg to 90deg, contrary to what
Elevation should be normalized to be within [-90, 90]
with 90 degrees directly above the users head
and -90 degrees directly below (North and South poles on a sphere
centered at the users head)
 > is stated in the definition of the angle unit?
 > Also...  In the definition of angle units, the draft states that "10deg 
 > and 350 deg are equivalent"  Shouldn't this read "10deg and 370deg are 
 > equivalent" since 10deg is co-related to 370deg, and since there is no 
 > whitespace permitted between the number and unit identifier?

The above correction is corrrect --350 degrees == -10 degrees
 > And one final side note...  Would it be possible to include named anchors 
 > for each property in drafts like WD-acss and WD-print?  This allows me to 
 > provide direct links from property names in CSSCheck to the property spec, 
 > and would also facilitate a helpful table of contents in the WDs 
 > themselves.
 > Version: PGP for Personal Privacy 5.0
 > Charset: noconv
 > K0rsO3go2ZKV+jerC+lD12dYETFoZJKUKP4qGa5JJdmRP4ATJ/WA51GKqNbbstpI
 > FdrdxUgxRO8fZo5DQ4yFluVzf6Ri5zlE
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 > Liam Quinn
 > ===============  http://www.htmlhelp.com/%7Eliam/  ===============
 > Web Design Group            Enhanced Designs, Web Site Development
 > http://www.htmlhelp.com/    http://enhanced-designs.com/
 > ======  PGP Key at http://www.htmlhelp.com/%7Eliam/pgp.html  =====

Best Regards,

      Adobe Systems                 Tel: 1 (408) 536 3945   (W14-129)
      Advanced Technology Group     Fax: 1 (408) 537 4042 
      (W14 129) 345 Park Avenue     Email: raman@adobe.com 
      San Jose , CA 95110 -2704     Email:  raman@cs.cornell.edu
      http://labrador.corp.adobe.com/~raman/raman.html (Adobe  Internal)
      http://www.cs.cornell.edu/Info/People/raman/raman.html  (Cornell)
    Disclaimer: The opinions expressed are my own and in no way should be taken
as representative of my employer, Adobe Systems Inc.
Received on Monday, 4 August 1997 18:22:27 UTC

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