// evaluate a point on a bezier-curve. t goes from 0 to 1
  static VT bezierAt(VT) (float t, const(VT)[] pts...) if (IsVectorDim!(VT, 2)) {
    assert(pts.length == 3 || pts.length == 4); // quadratic or cubic
    VT[4][2] xpts;
    xpts[0][0..pts.length] = pts[];
    int curidx = 0;
    foreach (immutable lc; 1..pts.length) {
      foreach (immutable idx; 0..pts.length-lc) xpts[1-curidx][idx] = xpts[curidx][idx].lerp(xpts[curidx][idx+1], t);
      curidx ^= 1;
    }
    return xpts[curidx][0];
  }

  enum BezierPoints = 16;
  foreach (immutable int pn; 0..BezierPoints) {
    float t = cast(float)pn/cast(float)(BezierPoints-1);
    auto pt = bezierAt(t, pt0, pt1, pt2); // you may add pt3 too
    drawPixel(pt);
  }

VT[4] bezier2cubic(VT) (in auto ref VT v0, in auto ref VT v1, in auto ref VT v2) if (IsVectorDim!(VT, 2)) {
  auto np0 = v0+(v1-v0)*2/3;
  auto np1 = v2+(v1-v2)*2/3;
  return [v0, np0, np1, v2];
}