private GetX ( System.Windows.Vector v ) : System.Double | ||
v | System.Windows.Vector | |
return | System.Double |
/// <summary> /// Attempts to find a slightly better parameterization for u on the given curve. /// </summary> protected void Reparameterize(int first, int last, CubicBezier curve) { List <VECTOR> pts = _pts; List <FLOAT> u = _u; int nPts = last - first; for (int i = 1; i < nPts; i++) { VECTOR p = pts[first + i]; FLOAT t = u[i]; FLOAT ti = 1 - t; // Control vertices for Q' VECTOR qp0 = (curve.p1 - curve.p0) * 3; VECTOR qp1 = (curve.p2 - curve.p1) * 3; VECTOR qp2 = (curve.p3 - curve.p2) * 3; // Control vertices for Q'' VECTOR qpp0 = (qp1 - qp0) * 2; VECTOR qpp1 = (qp2 - qp1) * 2; // Evaluate Q(t), Q'(t), and Q''(t) VECTOR p0 = curve.Sample(t); VECTOR p1 = ((ti * ti) * qp0) + ((2 * ti * t) * qp1) + ((t * t) * qp2); VECTOR p2 = (ti * qpp0) + (t * qpp1); // these are the actual fitting calculations using http://en.wikipedia.org/wiki/Newton%27s_method // We can't just use .X and .Y because Unity uses lower-case "x" and "y". FLOAT num = ((VectorHelper.GetX(p0) - VectorHelper.GetX(p)) * VectorHelper.GetX(p1)) + ((VectorHelper.GetY(p0) - VectorHelper.GetY(p)) * VectorHelper.GetY(p1)); FLOAT den = (VectorHelper.GetX(p1) * VectorHelper.GetX(p1)) + (VectorHelper.GetY(p1) * VectorHelper.GetY(p1)) + ((VectorHelper.GetX(p0) - VectorHelper.GetX(p)) * VectorHelper.GetX(p2)) + ((VectorHelper.GetY(p0) - VectorHelper.GetY(p)) * VectorHelper.GetY(p2)); FLOAT newU = t - num / den; if (Math.Abs(den) > EPSILON && newU >= 0 && newU <= 1) { u[i] = newU; } } }