コード例 #1
0
  protected final void compute() {
    if (!(f.isDefined() && P.isDefined())) {
      tangent.setUndefined();
      return;
    }

    // first derivative
    if (df == null || !df.isDefined()) {
      tangent.setUndefined();
      return;
    }

    // calc the tangent;
    double feval[] = new double[2];
    double dfeval[] = new double[2];

    double tvalue = f.getClosestParameter(P, f.getMinParameter());
    f.evaluateCurve(tvalue, feval);
    df.evaluateCurve(tvalue, dfeval);
    tangent.setCoords(-dfeval[1], dfeval[0], feval[0] * dfeval[1] - dfeval[0] * feval[1]);

    if (!pointOnCurve) T.setCoords(feval[0], feval[1], 1.0);
  }
コード例 #2
0
ファイル: AlgoDirectrix.java プロジェクト: kovzol/geogebra
  // calc axes
  protected final void compute() {
    // only parabola has directrix
    if (c.type == GeoConic.CONIC_PARABOLA) {
      // directrix has direction of second eigenvector
      // through point (b - p/2* eigenvec1)
      directrix.x = -eigenvec[1].y;
      directrix.y = eigenvec[1].x;
      double px = b.x - c.p / 2.0 * eigenvec[0].x;
      double py = b.y - c.p / 2.0 * eigenvec[0].y;
      directrix.z = -(directrix.x * px + directrix.y * py);

      P.setCoords(px, py, 1.0);
    } else directrix.setUndefined();
  }