example/threejs/asset/three.js
function( t ) {

		var delta = 0.0001;
		var t1 = t - delta;
		var t2 = t + delta;

		// Capping in case of danger

		if ( t1 < 0 ) t1 = 0;
		if ( t2 > 1 ) t2 = 1;

		var pt1 = this.getPoint( t1 );
		var pt2 = this.getPoint( t2 );

		var vec = pt2.clone().sub( pt1 );
		return vec.normalize();

	}
function( t ) {

		var delta = 0.0001;
		var t1 = t - delta;
		var t2 = t + delta;

		// Capping in case of danger

		if ( t1 < 0 ) t1 = 0;
		if ( t2 > 1 ) t2 = 1;

		var pt1 = this.getPoint( t1 );
		var pt2 = this.getPoint( t2 );

		var vec = pt2.clone().sub( pt1 );
		return vec.normalize();

	}
function ( t ) { var delta = 0.0001 ; var t1 = t - delta ; var t2 = t + delta ; // Capping in case of danger if ( t1 < 0 ) t1 = 0 ; if ( t2 > 1 ) t2 = 1 ; var pt1 = this . getPoint ( t1 ) ; var pt2 = this . getPoint ( t2 ) ; var vec = pt2 . clone ( ) . sub ( pt1 ) ; return vec . normalize ( ) ; }
Returns a unit vector tangent at t In case any sub curve does not implement its tangent derivation, 2 points a small delta apart will be used to find its gradient which seems to give a reasonable approximation
Returns a unit vector tangent at t In case any sub curve does not implement its tangent derivation 2 points a small delta apart will be used to find its gradient which seems to give a reasonable approximation