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OpenGL and hit testing

From: Richard Schwerdtfeger <schwer@us.ibm.com>
Date: Fri, 20 Apr 2012 14:29:21 -0500
To: "Dominic Mazzoni" <dmazzoni@google.com>, public-canvas-api@w3.org
Cc: kbr@google.com, public-html-a11y@w3.org, "HTMLWG WG" <public-html@w3.org>
Message-ID: <OF81708E17.50093A32-ON862579E6.006259E2-862579E6.006B0E71@us.ibm.com>


The current proposals being created for canvas accessibility and hit
testing do not accommodate 3D. Specifically, Canvas 2D supports a Path
whereas WebGL really does not. Kenneth Russell raised this issue to me at
SXSW as did Dominic Mazzoni on a call today.

Dominic Mazzoni and I dug into this a little deeper this morning and it is
is clear there are a number of strategies in 3D that are employed to
address hit testing. For example, transparency might apply to hit testing
in 3D.

It occurred to us that one way to address this would be to use Regions as
an abstraction in canvas 2D where instead of creating a Path call it a
createRegion ( I am thinking of Ted O'Connors upcoming change proposal) to
coincide with addHitRegion(). For 2D graphics this would be treated as a
Path and for 3D we would let the 3D Context apply to whatever their
interpretation of a region is based on the hit testing strategy employed.

Ted, what do you thinK?

Rich


Rich Schwerdtfeger
Received on Friday, 20 April 2012 19:30:02 GMT

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