function supertriangle(vertices) {
    var xmin = Number.POSITIVE_INFINITY;
    var ymin = Number.POSITIVE_INFINITY;
    var xmax = Number.NEGATIVE_INFINITY;
    var ymax = Number.NEGATIVE_INFINITY;
    var i, dx, dy, dmax, xmid, ymid;

    for (i = vertices.length; i--; ) {
        if (vertices[i][0] < xmin) { xmin = vertices[i][0]; }
        if (vertices[i][0] > xmax) { xmax = vertices[i][0]; }
        if (vertices[i][1] < ymin) { ymin = vertices[i][1]; }
        if (vertices[i][1] > ymax) { ymax = vertices[i][1]; }
    }

    dx = xmax - xmin;
    dy = ymax - ymin;
    dmax = Math.max(dx, dy);
    xmid = xmin + dx * 0.5;
    ymid = ymin + dy * 0.5;

    return [
        [xmid - 20 * dmax, ymid -      dmax],
        [xmid            , ymid + 20 * dmax],
        [xmid + 20 * dmax, ymid -      dmax]
    ];
}
Clone a new Blend1D clip
@param {boolean} cloneInputs True if clone the input clips
@return {clay.animation.Blend1DClip}