[x3d-public] setUSE in X3DJSAIL

[John Carlson]

Roy,

I imagine setUSE was chosen because it was either an attribute in XML or property @USE in JSON, and we were translating XML and JSON to Java, Nashorn JavaScript and Python. Please provide an equivalent conversion of an X3D XML file to C,C++, or C# which does not use setUSE and uses SAI as you suggest. If you can do it, we will copy you.

We would like to use chained methods with a minimum of extra variables (ideally, just one variable for whole scenegraph will do—not currently achieved). In addition, we would like to take advantage of type safety as much as possible.  Please consider type safety when writing your code.

There are DOM -> various languages examples you can find in X3DJSONLD/src/main/node.  JavaScriptSerializer.js and JavaSerializer.js are good ones.  You can use any language you want, but if you integrate with X3DJSONLD (json2all.js), it will be integrated into my test suite.

It is also possible that setUSE was required in the concrete classes (not SAI that I know of) and extracting setUSE up to the interface was a good idea.  I think this can be solved by providing an intermediate interface.

Thanks,

John

Sent from Mail for Windows 10

From: Roy Walmsley
Sent: Thursday, July 20, 2017 9:13 AM
To: 'Don Brutzman'
Cc: 'John Carlson'; 'list'
Subject: setUSE in X3DJSAIL

Hi Don,

I note that in X3DJSAIL you have a “setUSE” method defined in all node classes. I don’t see any point of having this method.

My thinking is as follows. Please correct it as necessary.

X3DJSAIL is meant to be an interface for an implementation of the Java Language binding – ISO/IEC 19777-2.

The SAI 19775-2 has no service related to “USE”. So it does not appear in the Java language binding.

Consider that an instance of a node (say Material) has been  loaded into memory and added into a scene. Then consider that further down in the scene it is desirable to implement a “USE”. What are the steps?

The first would be to call the Java implementation of the SAI execution context service “getNode”, with the SAIString parameter set to the DEF name, and the SAIAction parameter set to DEFNode.  In the standard ISO/IEC 19777-2 V3.0, clause 6.4.6 getNode the defined method is getNamedNode. What is your equivalent function in X3DJSAIL?

Having obtained a node reference for the DEF’d node, let’s assume you also have a node reference for the node that is to be the parent of the USE node, which I will assume for this example will be Appearance. 

You now need to obtain a reference for the “material” field of the Appearance node.  We need to  use the SAI service getField, defined in 6.6.4 getField in ISO/IEC 19775-2. The Java language binding lists this as getField in clause 6.6.4 of ISO/IEC 19777-2. What is your equivalent function in X3DJSAIL?

Now that we have the field reference, and the node reference to add, we can finally make a call to the SAI service setValue, defined in 6.7.6 setValue in ISO/IEC 19775-2. The Java language binding lists this as setValue in 6.7.6 of ISO/IEC 19777-2. What is your equivalent function in X3DJSAIL?

Final comments relate to garbage management. The implementation will probably want some way to remember that the same node reference has been used in multiple places. That is something internal to the implementation, and not anything for the interface.

So, in conclusion, I don’t see a need for your setUSE method. And it is not in the SAI.

All the best,

Roy

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