[x3d-public] Interesting Example; Script source code CDATA escaping, references
Don Brutzman
brutzman at nps.edu
Sat Jun 18 08:43:49 PDT 2016
Sounds great, looks like what you have should work. You might also want to check on ampersand (&, &) escaping.
This is why it is good practice in XML encoding to wrap any javascript source within a Script node inside a CDATA block. CDATA "character data" means the xml/xhtml parser must avoid escaping any characters like < into < etc.
Examples and references follow.
From X3D specification ISO/IEC 19776-1 XML encoding:
6.2.179 Script
http://www.web3d.org/documents/specifications/19776-1/V3.3/Part01/EncodingOfNodes.html#Script
========================================================
<Script DEF=""
USE=""
directOutput="false"
mustEvaluate="false"
url=' '
containerField="children"
>
<IS> <connect nodeField="" protoField=""/> </IS>
<field name="" type="" accessType="" value=""/>
<![CDATA[
ecmascript:
// contained script code here (if any)
]]>
</Script>
========================================================
and
4.3.13 Encapsulating Script node code
http://www.web3d.org/documents/specifications/19776-1/V3.3/Part01/concepts.html#EncapsulatingScriptNodeCode
========================================================
Code for scripts should not be placed so as to be parsed by XML parsers. Therefore, such code should be encapsulated to avoid such parsing. The preferred method to encapsulate source code in a Script node is to wrap it in a child CDATA construct following the <field/> and <IS><connect/></IS> definitions. The CDATA construct (see 2.[XML]) ensures that all contained characters are treated literally without further escaping or modification.
If both a url field and a CDATA clause are encountered, the url field is processed first. Thus, the CDATA construct can also be considered equivalent to one additional value appended to the url MFString array. This ordering allows an online script code url to take priority over fallback default script code in the CDATA construct. This ordering also allows run-time updates if a viewer is connected to the network, if so desired by the originating author.
EXAMPLE The following example demonstrates the use of a CDATA construct within a Script node:
<Script directOutput='true'>
<field name='ROOT' type='SFNode' accessType='initializeOnly'>
<Transform USE='ROOT'/>
</field>
<![CDATA[
javascript:
function R ()
{
return Math.random();
}
function initialize()
{
for (i=0; i < 10; i++)
{
rand1 = 100*R();
rand2 = 100*R();
rand3 = 20*R();
rand4 = 40*R();
rand5 = 20*R();
string =
'Transform {' +
' translation ' + rand1 + ' 0 ' + rand2 +
' children [' +
' Shape {' +
' appearance Appearance {' +
' material Material {' +
' diffuseColor ' + R() + ' ' + R() + ' ' + R() +
' }' +
' }' +
' geometry Box {' +
' size ' + rand3 + ' ' + rand4 + ' ' + rand5 +
' }' +
' }' +
' ]' +
'}';
newNode = Browser.createVrmlFromString(string);
ROOT.children[i] = newNode[0];
}
}
]]>
</Script>
========================================================
Additional references:
X3D Scene Authoring Hints: Scripts
http://www.web3d.org/x3d/content/examples/X3dSceneAuthoringHints.html#Scripts
X3D Tooltips: Scripts
http://www.web3d.org/x3d/content/X3dTooltips.html#Script
X3D Example Archives: X3D for Web Authors, Chapter 09 - Event Utilities Scripting
http://x3dgraphics.com/examples/X3dForWebAuthors/Chapter09-EventUtilitiesScripting
X3D for Web Authors, chapter 9
X3D for Web Authors, slideset, Event Utilities and Scripting (106 slides)
http://x3dgraphics.com/slidesets/X3dForWebAuthors/Chapter09-EventUtilitiesScripting.pdf
(note first half of document is just presentation slides, second half is slides + annotations)
Course videos: Event Utilities, Scripting
https://www.youtube.com/playlist?list=PLuSIsM-86sik26mcDz0w_wdFXOUp56FTr
https://www.movesinstitute.org/Video/Courses/X3dForWebAuthors/X3dForWebAuthorsVideo.html#9
On 6/18/2016 3:25 AM, John Carlson wrote:
> Okay, I was able to make gears.json work with the X3D JSON Loader and the server side proto expander with cobweb. I may have to work on the client side prototype expander some more to make it work with X3DOM (likely it’s a script issue instead).
>
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> What I did was replace < and > before sending to CreateX3DFromString, avoiding any web browser interpretation.
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> John
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>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10
>
>
>
> *From: *John Carlson <mailto:yottzumm at gmail.com>
> *Sent: *Saturday, June 18, 2016 3:42 AM
> *To: *Roy Walmsley <mailto:roy.walmsley at ntlworld.com>; Don Brutzman <mailto:brutzman at nps.edu>
> *Cc: *Holger Seelig <mailto:holger.seelig at yahoo.de>; x3d-public at web3d.org <mailto:x3d-public at web3d.org>
> *Subject: *RE: Interesting Example
>
>
>
> Okay, I figured out why the X3D JSON Loader wouldn’t load it. When I serialize the JSON to XML, the < and > get converted to < and >. These are not valid to VRMLScript? I am not sure. I will try to do a replacement. I think the best thing to do may be to create a CDATA Section instead of a text node, but I’m not ready to do that (doesn’t work with HTML, I’d say off the cuff).
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> I do have this, which appears to be partially working:
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> // Fix CDATA sections
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> xmlstr = xmlstr.replace(/<!\[CDATA\[/g, "<![CDATA[");
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> xmlstr = xmlstr.replace(/\]\]>/g, "]]>");
>
> do {
>
> var xmlstr2 = xmlstr;
>
> xmlstr = xmlstr2.replace(/(\<\!\[CDATA\[(.|\n)*)<((.|\n)*\]\]\>)/gi, "$1<$3");
>
> } while (xmlstr !== xmlstr2);
>
> do {
>
> xmlstr2 = xmlstr;
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> xmlstr = xmlstr2.replace(/(\<\!\[CDATA\[(.|\n)*)>((.|\n)*\]\]\>)/gi, "$1>$3");
>
> } while (xmlstr !== xmlstr2);
>
>
>
> John
>
>
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10
>
>
>
> *From: *John Carlson <mailto:yottzumm at gmail.com>
> *Sent: *Saturday, June 18, 2016 3:15 AM
> *To: *Roy Walmsley <mailto:roy.walmsley at ntlworld.com>; Don Brutzman <mailto:brutzman at nps.edu>
> *Cc: *Holger Seelig <mailto:holger.seelig at yahoo.de>; x3d-public at web3d.org <mailto:x3d-public at web3d.org>
> *Subject: *RE: Interesting Example
>
>
>
> This example has a lot of scripting, and I doubt if my prototype expander is up to dealing with scripts yet. If we could get
>
> a version without scripts, I could try loading it. As it is, even without the prototype expander, the X3D JSON Loader will not load gears.json, even with a Cobweb renderer. Something to work on.
>
>
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10
>
>
>
> *From: *Roy Walmsley <mailto:roy.walmsley at ntlworld.com>
> *Sent: *Friday, June 17, 2016 6:32 AM
> *To: *John Carlson <mailto:yottzumm at gmail.com>; Don Brutzman <mailto:brutzman at nps.edu>
> *Cc: *Holger Seelig <mailto:holger.seelig at yahoo.de>; x3d-public at web3d.org <mailto:x3d-public at web3d.org>
> *Subject: *Interesting Example
>
>
>
> Hi,
>
>
>
> I have come across an interesting example, relating to the use of Scripts/Prototypes.
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>
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> It is on the Cobweb site at http://titania.create3000.de/cobweb/. Scroll down to examples, navigate to Page 3 of the Examples list, and choose “Gears”.
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> This example is also available on Holger’s GitHub site at https://github.com/create3000/Library/tree/master/Examples/Gears. There are four files, of which two are XML encoded X3D. The file Rotor.x3d supplies a prototype declaration that is used within gears.x3d.
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> Try opening the file gears.x3d in different browsers!
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> I don’t know how you would get on with this one, John, in your prototype expander.
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> Roy
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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
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