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+/**
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+ * Spline from Tween.js, slightly optimized
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+ * http://sole.github.com/tween.js/examples/05_spline.html
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+ *
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+ * @author mrdoob / http://mrdoob.com/
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+ */
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+
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+THREE.Spline = function () {
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+
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+ var c = [], v3 = { x: 0, y: 0, z: 0 },
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+ point, intPoint, weight, w2, w3,
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+ pa, pb, pc, pd;
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+
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+ this.get2DPoint = function ( points, k ) {
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+
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+ point = ( points.length - 1 ) * k;
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+ intPoint = Math.floor( point );
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+ weight = point - intPoint;
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+
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+ c[ 0 ] = intPoint == 0 ? intPoint : intPoint - 1;
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+ c[ 1 ] = intPoint;
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+ c[ 2 ] = intPoint > points.length - 2 ? intPoint : intPoint + 1;
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+ c[ 3 ] = intPoint > points.length - 3 ? intPoint : intPoint + 2;
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+
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+ pa = points[ c[ 0 ] ];
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+ pb = points[ c[ 1 ] ];
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+ pc = points[ c[ 2 ] ];
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+ pd = points[ c[ 3 ] ];
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+
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+ w2 = weight * weight;
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+ w3 = weight * w2;
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+
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+ v3.x = interpolate( pa.x, pb.x, pc.x, pd.x, weight, w2, w3 );
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+ v3.y = interpolate( pa.y, pb.y, pc.y, pd.y, weight, w2, w3 );
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+ v3.z = interpolate( pa.z, pb.z, pc.z, pd.z, weight, w2, w3 );
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+
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+ return v3;
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+
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+ }
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+
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+ // Catmull-Rom
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+
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+ function interpolate( p0, p1, p2, p3, t, t2, t3 ) {
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+
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+ var v0 = ( p2 - p0 ) * 0.5,
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+ v1 = ( p3 - p1 ) * 0.5;
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+
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+ return ( 2 * ( p1 - p2 ) + v0 + v1 ) * t3 + ( - 3 * ( p1 - p2 ) - 2 * v0 - v1 ) * t2 + v0 * t + p1;
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+
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+ }
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+
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+};
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alteredq