function transformPoint(m, v, dst) {
    dst = dst || v3.create();
    var v0 = v[0];
    var v1 = v[1];
    var v2 = v[2];
    var d = v0 * m[0 * 4 + 3] + v1 * m[1 * 4 + 3] + v2 * m[2 * 4 + 3] + m[3 * 4 + 3];

    dst[0] = (v0 * m[0 * 4 + 0] + v1 * m[1 * 4 + 0] + v2 * m[2 * 4 + 0] + m[3 * 4 + 0]) / d;
    dst[1] = (v0 * m[0 * 4 + 1] + v1 * m[1 * 4 + 1] + v2 * m[2 * 4 + 1] + m[3 * 4 + 1]) / d;
    dst[2] = (v0 * m[0 * 4 + 2] + v1 * m[1 * 4 + 2] + v2 * m[2 * 4 + 2] + m[3 * 4 + 2]) / d;

    return dst;
  }
Takes a 4-by-4 matrix and a vector with 3 entries,
interprets the vector as a point, transforms that point by the matrix, and
returns the result as a vector with 3 entries.
@param {module:twgl/m4.Mat4} m The matrix.
@param {Vec3} v The point.
@param {Vec3} dst optional vec3 to store result
@return {Vec3} dst or new vec3 if not provided
@memberOf module:twgl/m4