[x3d-public] X3DJSAIL: Many DEFs with same value

[John Carlson]

Summary: to employ multiple DEFs with same value, employ a table per name
scope of DEF information in per Java thread java.lang.ThreadLocal memory
for encoded output with one DEF per DEF/USE value.  See bolded table
description below.

Feel free to forward.

Is many DEFs with same value for a scenegraph node being considered in
discussions?  Say I want to addChild() the same Shape node several times to
different Transforms, and the Shape node or descendants have DEFs in them.
In X3DJSAIL, of course.   This is easily done in an SAI binding like
X3DJSAIL, just use the same variable passed to several addChild() methods.

If it is allowed, what comes out in XML?  I am hoping one leading DEF and
several USEs for backwards compatibility.  I think Castle has shown that
this is doable.

I am not saying VRML, XML, DOM, or HTML should have multiple parents of a
child node. If a browser wants to implement a proxy when a DEF/USE appears
more than once, they should be free to do that.  (Hint: JavaScript’s Proxy
class.) Maybe each mention of a DEF value (second or following) or USE
value (any natural number of them) should create a Proxy on setting or
adding?

I do think the encodings are doing the right thing, no changes there.  How
can we achieve that output and support multiple parents (references or
proxies to children) in X3DJSAIL with one DEF node per DEF value output?

I’m particularly wondering for X3DJSAIL.

Do we need proxies, or will table(s) also solve the issue of multiple DEFs,
and replace all but the first with USE on output?  Also perhaps assuming
there’s a DEF table per name scope.  How does X3DJSAIL support name scopes?
(I’m clueless, currently).  *I’m imagining a table with DEF_value,
DEF_found, reference_count, DEF_nodes and USE_nodes columns.  Maybe a
name_scope and node_type_name as well.*  These table(s) would be
initialized when output begins potentially when a name scope is entered,
and filled out as the XML is created.   Multiple threads?  The table can be
stored in ThreadLocal memory.  Bingo, if it’s still a thing.

Please let me know if such a thing is already available.

Someone else can solve for X3DPSAIL?

Will this also handle USE before DEF?

John
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