sketchpunk · January 7, 2021 20:59
diff --git a/QuadTreeID.html b/QuadTreeID.html
 <html>
 <script>

 window.onload = function(){
    let qID = 0;

    qID = QuadTreeID.set( qID, 2, QuadTreeID.A );
    qID = QuadTreeID.set( qID, 0, QuadTreeID.C );
    qID = QuadTreeID.set( qID, 3, QuadTreeID.D );
    qID = QuadTreeID.set( qID, 1, QuadTreeID.B );
    qID = QuadTreeID.set( qID, 4, QuadTreeID.C );

    QuadTreeID.debug( qID );
    /* Max Level :  4
    Bits : 0010 01 10 00 11 01
    LVL: 0  :  C-01
    LVL: 1  :  B-10
    LVL: 2  :  A-00
    LVL: 3  :  D-11
    LVL: 4  :  C-01 */
 };

 /*
 32 Bytes
 - 4 bytes for Total Levels
 28
 - Last bit defines negative, 
 so only have 26 bytes left.
 26/2 = 13

 Maximum level of LOD of 13 using ints
 1,2,4,8
 */

 class QuadTreeID{
    static A = 0;
    static B = 1;
    static C = 2;
    static D = 3;

    static set( qid, lvl, quad ){
        let shift   = (lvl * 2) + 4;             // How many bits to shift based on level
        let i       = quad << shift;             // Quad ID at Bit Level
        let mask    = ~( (3 << shift) + 15 );    // Create Mask to clear out lvl and quad of old ID : ex. 111100110000
        lvl         = Math.max( lvl, qid & 15 ); // Grab the first 4 Bits which defines the level.
        return (qid & mask) ^ lvl ^ i;           // Rebuild ID with new level and Quadrant ID
    }

    static debug( id ){
        let i, v, q, lvl = id & 15;
        console.log( "Max Level : ", lvl );
        
        let bits = "Bits : "; // ex output : BITS: 1000 10 11 01
        let end = (id & 15) * 2 + 6;
        for( i=0; i < end; i++ ) bits += ((id >> i) & 1) + (( (i & 1) && i > 2 )?" ":"");
        console.log( bits );

        for( i=0; i <= lvl; i++ ){
            v = ( id >> ((i * 2) + 4) ) & 3;
            switch( v ){
                case this.A : q = "A-00"; break;
                case this.B : q = "B-10"; break;
                case this.C : q = "C-01"; break;
                case this.D : q = "D-11"; break;
                default: q = "X";   // error
            }
            console.log( "LVL:", i, " : ", q);
        }
    }
 }

 </script>
 </html>
	<html>
	<script>

	window.onload = function(){
	let qID = 0;

	qID = QuadTreeID.set( qID, 2, QuadTreeID.A );
	qID = QuadTreeID.set( qID, 0, QuadTreeID.C );
	qID = QuadTreeID.set( qID, 3, QuadTreeID.D );
	qID = QuadTreeID.set( qID, 1, QuadTreeID.B );
	qID = QuadTreeID.set( qID, 4, QuadTreeID.C );

	QuadTreeID.debug( qID );
	/* Max Level : 4
	Bits : 0010 01 10 00 11 01
	LVL: 0 : C-01
	LVL: 1 : B-10
	LVL: 2 : A-00
	LVL: 3 : D-11
	LVL: 4 : C-01 */
	};

	/*
	32 Bytes
	- 4 bytes for Total Levels
	28
	- Last bit defines negative,
	so only have 26 bytes left.
	26/2 = 13

	Maximum level of LOD of 13 using ints
	1,2,4,8
	*/

	class QuadTreeID{
	static A = 0;
	static B = 1;
	static C = 2;
	static D = 3;

	static set( qid, lvl, quad ){
	let shift = (lvl * 2) + 4; // How many bits to shift based on level
	let i = quad << shift; // Quad ID at Bit Level
	let mask = ~( (3 << shift) + 15 ); // Create Mask to clear out lvl and quad of old ID : ex. 111100110000
	lvl = Math.max( lvl, qid & 15 ); // Grab the first 4 Bits which defines the level.
	return (qid & mask) ^ lvl ^ i; // Rebuild ID with new level and Quadrant ID
	}

	static debug( id ){
	let i, v, q, lvl = id & 15;
	console.log( "Max Level : ", lvl );

	let bits = "Bits : "; // ex output : BITS: 1000 10 11 01
	let end = (id & 15) * 2 + 6;
	for( i=0; i < end; i++ ) bits += ((id >> i) & 1) + (( (i & 1) && i > 2 )?" ":"");
	console.log( bits );

	for( i=0; i <= lvl; i++ ){
	v = ( id >> ((i * 2) + 4) ) & 3;
	switch( v ){
	case this.A : q = "A-00"; break;
	case this.B : q = "B-10"; break;
	case this.C : q = "C-01"; break;
	case this.D : q = "D-11"; break;
	default: q = "X"; // error
	}
	console.log( "LVL:", i, " : ", q);
	}
	}
	}

	</script>
	</html>