[x3d-public] [x3d] Spec Comment by on 19775-1: Abstract X3D Definitions - V3.3: Material alpha modulation with Lighting on (Mantis 973)

[Don Brutzman]

Doug: thanks for this helpful specification comment.

Roy has entered this topic as Mantis issue 973:

	http://www.web3d.org/member-only/mantis/view.php?id=973

Am moving this discussion to the x3d-public mailing list.  Additional insight is welcome.


On 8/15/2016 9:56 AM, Spec Feedback wrote:
> Comment on 19775-1: Abstract X3D Definitions - V3.3
> 17.2.2.3
> http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components/lighting.html#Lightingon
>
> -----------------
> "The Material's transparency field modulates the alpha in the texture. Hence,
> a transparency of 0 will result in an alpha equal to that of the texture. A
> transparency of 1 will result in an alpha of 0 regardless of the value in the
> texture."
> That doesn't seem to me to be what browsers Octaga, InstantReality, or
> Cortona are doing, and its not what table 17-3 and the Lighting equation say
> is happening. In the table, alpha is never 'modulated' ie there's never an
> alpha= AT * (1-TM)
> - freewrl version 3 and vivaty do modulate.
> The following 29C, 29D .wrl have texture alpha and material transparency=1,
> show differently as noted above.
> http://dug9.users.sourceforge.net/web3d/tests/DebateModulateAlpha.zip
> or directly:
> http://dug9.users.sourceforge.net/web3d/tests/29C.wrl
> http://dug9.users.sourceforge.net/web3d/tests/29D.wrl
>
> -----------------
>
> Submitted on Monday, 2016,  August 15 - 9:56am
> by  (Doug Sanden )
> IP: 75.159.141.42
>
> See: http://www.web3d.org/node/1694/submission/895

all the best, Don
-- 
Don Brutzman  Naval Postgraduate School, Code USW/Br       brutzman at nps.edu
Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA   +1.831.656.2149
X3D graphics, virtual worlds, navy robotics http://faculty.nps.edu/brutzman