[x3d-public] Everit summary, auto-generated versus roy's, X3DUOM min/max for rotation. RFE for X3DUOM

[Don Brutzman]

Hi John.  As discussed today, SFRotation normalization is perhaps desirable but often not observed in content (meaning X3D models).

This is especially true for conversion outputs which can be pretty sloppy.

So let's support such cleanup but not make that the default for validation.  You might want both options in JSON Schema (with one commented out).

I did find a normalize() method for SFRotation in X3DJSAIL.

	/**
	 * Utility method to normalize this rotation value: unit length for axis-angle vector, angle in range [0-2pi] radians, rotation with zero-length axis is reset to DEFAULT_VALUE.
	 * @return {@link SFRotation} - namely <i>this</i> same object to allow sequential method pipelining (i.e. consecutive method invocations on the same object).
	 */
	public SFRotation normalize()
	{
		float length = (float) Math.sqrt(SFRotation[0]*SFRotation[0] + SFRotation[1]*SFRotation[1] + +SFRotation[2]*SFRotation[2]);
		if (length == 0.0f)
		{
			SFRotation = java.util.Arrays.copyOf(DEFAULT_VALUE, DEFAULT_VALUE.length); // must be separate copy
			System.out.println ("SFRotation.normalize(): zero-length axis encountered, reset entire SFRotation to DEFAULT_VALUE: " + DEFAULT_VALUE);
		}
		else
		{
			SFRotation[0] = SFRotation[0] / length;
			SFRotation[1] = SFRotation[1] / length;
			SFRotation[2] = SFRotation[2] / length;
			while (SFRotation[3] < 0.0f)
				   SFRotation[3] += 2.0f * Math.PI;
			while (SFRotation[3] >= 2.0f * Math.PI)
				   SFRotation[3] -= 2.0f * Math.PI;
		}
		return this;
	}

Will add corresponding normalize() method for MFRotation that simply walks through the list of contained SFRotation values.

Will similarly add such functionality in X3DUOM documentation, X3D regex alternative, X3DPSAIL x3d.py.  Possibly X3D Schematron and X3dTidy as well (insofar as possible with string manipulation).

... and some fine day, if someone picks up the Chisel open source, we can confirm (or add) normalization options there as well.

If we listen closely, am maybe hearing a swamp draining in the far-off distance...

Thanks for your many efforts.

On 4/1/2021 9:06 PM, John Carlson wrote:
>  From what I see online, the @rotation X,Y,Z should be normalized.
> Therefore, the min/max ranges in Roy's X3D JSON schema should be maintained.
> 
> I will go ahead and copy/paste Roy's rotation sub-schema into the X3D
> JSON schema generator, in hopes that the normalization requirements will
> fit into X3DUOM at some point.
> 
> Thanks,
> 
> John
> 
> On 4/1/21 8:53 PM, John Carlson wrote:
>> Is rotation "normalization" something the schematron finds? This seems
>> like something valuable that we don't want to lose. 

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