[x3d-public] questions on X3DJSAIL usage.

[John Carlson]

Yes, sub-classing (in JavaScript) would be OK.  I would have to think about how do that in Java.  Hmm.

My understanding of the USE field is to create multiple parents.  setUSE() would have a similar purpose.

Which is why I would consider a third option of creating multiple parents in SAI (scenegraph), not DOM.

If we use DOM, then your solutions would likely work.

I think we may need more concrete uses.  The HelloWorldProgram.java program in the www.web3d.org/x3d/stylesheets/java/examples (on sourceforge) has some uses of setUSE we could look at.

It’s likely we really need to concentrate on, indeed, what exactly setUSE is supposed to do.   Does it merely set a field, or is there some more internal actions going on?

John

Sent from Mail for Windows 10

From: Leonard Daly
Sent: Monday, May 6, 2019 6:17 PM
To: x3d-public at web3d.org
Subject: Re: [x3d-public] questions on X3DJSAIL usage.

John,

I guess I am not sure what setUSE is suppose to do. I my world of 3D graphics (note that this is not X3D), a node may only have a single parent. If the intent of setUse is to duplicate the content tree starting with another node, I would need to decide if that is better done as a deep copy (independent content) or the DEF node is to be sub-classed. Also note that for me, SAI === DOM + some 3D interfaces.

A deep copy would need to copy the node and attribute structure and content starting with the identified node. I would need to modify the ID attribute values so there were no duplicates, probably defining a unique suffix at the start of the copy operation and appending that to each ID value from the original tree. Note that the copy operation needs to avoid copying any non-DOM-tree objects. I would likely first consider converting the DOM-tree from the source ID to an HTML string, then parse that into a DOM-tree not connected (yet) to the document. At that point, updating the IDs is easier. Once the copying is complete and the DOM updated, there is no relationship between the original source nodes and the new nodes. There are situations where this works well, and there are times when it doesn't really work at all.

The other choice is more programmatic in nature. It would create 3D objects/structure, but not directly include those objects in the DOM-tree. It would probably be easier to established the original nodes as a (non-X3D) prototype that is not directly instantiated. "USE" references references would sub-class the prototype and instantiate the sub-class, potentially overriding some "methods" or "data". Changes to the prototype would be propagated to all of the sub-classes. This method is more complex, and I have not thought it out as well (and deeply).

I am not sure if this answers your question/request.

Leonard Daly



Leonard, can you explain for us how we can write an SAI program avoiding setUSE()?  Apparently, my explanations aren’t getting through.
 
John
 
Sent from Mail for Windows 10
 
From: Brutzman, Donald (Don) (CIV)
Sent: Monday, May 6, 2019 2:18 AM
To: John Carlson; aono at tut.jp
Cc: X3D Graphics public mailing list
Subject: Re: questions on X3DJSAIL usage.
 
On 5/4/2019 4:15 PM, John Carlson wrote:
> I’m waiting for a response on whether I should stop using setUSE() (except in cases where > 1 fields are used in a node) in programs using X3DJSAIL.
> 
> Thanks!
> 
> John
 
Hmmm, perhaps I'm not understanding your question... but here is an attempt at a simple answer.  Plus some additional syntactic sugar.
 
1. I think a programmer utilizes setUSE() whenever you need to set a USE value on a node.
 
Example excerpts:
http://x3dgraphics.com/examples/X3dForWebAuthors/Chapter01TechnicalOverview
 
HelloWorld.x3d
 
       <Transform translation='0 -2 0'>
         <Shape>
           <Text DEF='TextMessage' string='"Hello" "world!"'>
             <FontStyle justify='"MIDDLE" "MIDDLE"'/>
           </Text>
           <Appearance>
             <Material USE='MaterialLightBlue'/>
           </Appearance>
         </Shape>
       </Transform>
 
HelloWorld.java
 
       .addChild(new TransformObject().setTranslation(0.0f,-2.0f,0.0f)
         .addChild(new ShapeObject()
           .setGeometry(new TextObject("TextMessage").setString(new MFStringObject("\"Hello\" \"world!\""))
             .setFontStyle(new FontStyleObject().setJustify(FontStyleObject.JUSTIFY_MIDDLE_MIDDLE)))
           .setAppearance(new AppearanceObject()
             .setMaterial(new MaterialObject().setUSE("MaterialLightBlue")))))));
 
HelloWorld.py
 
      .addChild(Transform() \
       .setTranslation(SFVec3f([0,-2,0])) \
       .addChild(Shape() \
        .setGeometry(Text() \
         .setDEF(SFString("TextMessage")) \
         .setString(MFString(["Hello","world!"])) \
         .setFontStyle(FontStyle() \
          .setJustify(MFString(["MIDDLE","MIDDLE"])) \
         ) \
        ) \
        .setAppearance(Appearance() \
         .setMaterial(Material() \
          .setUSE(SFString("MaterialLightBlue")) \
         ) \
        ) \
       ) \
      )
 
2. Note that if we start putting field adjustments on the same line, the structure for .java and .py are nearly identical.
 
Other syntax tightening is further possible in .py version:
- no apparent need to wrap SFString() in python syntax
- I suspect that MFString() wrapping is also superfluous, hopefully we can just use ["Hello","world!"]
- Similarly might try replacing SFVec3f([0,-2,0]) with [0,-2,0] - we're getting more Pythonic now!
- indenting with two space characters makes scene-graph structure more evident.
 
3. Spent the day refactoring the X3D Examples Archive projects from Netbeans plain-old freeform projects to Netbeans Java freeform projects.  This doesn't limit any functionality but it does make Java experimentation much simpler... menu items now include Compile/Run/Debug options.
 
4. Am further noticing from above that the following single-string .java construct
 
                .setString(new MFStringObject("\"Hello\" \"world!\""))
 
is more readable as a String array instead:
 
                .setString(new MFStringObject(new String[] {"Hello","world!"}))
 
or even more simply as:
 
                .setString(new String[] {"Hello","world!"})
 
Have improved X3dToJava.xslt conversions to simplify accordingly.  Will rerun all java conversions tonight and hopefully redeploy Web3D example archives tomorrow.  Then retest python build tomorrow night.
 
Also will redeploy X3DJSAIL with this improvement tonight.  Have also added initial PointProperties validation for X3Dv4, included source in full.jar for IDE javadoc/debugging, and fixed a number of X3DLoaderDOM geospatial errors.
 
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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-- 
Leonard Daly
3D Systems & Cloud Consultant
LA ACM SIGGRAPH Past Chair
President, Daly Realism - Creating the Future 

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