public static void Arrow(IPaintTo3D paintTo3D, GeoPoint base1, GeoPoint base2, GeoPoint apex)
{
GeoVector nor1 = (apex - base1) ^ (apex - base2);
nor1.Norm();
double l = base1 | base2;
GeoPoint c = new GeoPoint(base1, base2);
GeoPoint base3 = c + l / 2.0 * nor1;
GeoPoint base4 = c - l / 2.0 * nor1;
GeoVector nor2 = (apex - base3) ^ (apex - base4);
paintTo3D.Triangle(new GeoPoint[] { apex, base1, base2 }, new GeoVector[] { nor1, nor1, nor1 }, new int[] { 0, 1, 2 });
paintTo3D.Triangle(new GeoPoint[] { apex, base3, base4 }, new GeoVector[] { nor2, nor2, nor2 }, new int[] { 0, 1, 2 });
}
void IFeedBack.PaintTo3D(IPaintTo3D paintTo3D)
{
paintTo3D.UseZBuffer(true);
paintTo3D.Blending(true);
paintTo3D.SetColor(color);
GeoPoint[] pnts = new GeoPoint[4];
pnts[0] = pln.ToGlobal(new GeoPoint2D(-width / 2, -height / 2));
pnts[1] = pln.ToGlobal(new GeoPoint2D(width / 2, -height / 2));
pnts[2] = pln.ToGlobal(new GeoPoint2D(width / 2, height / 2));
pnts[3] = pln.ToGlobal(new GeoPoint2D(-width / 2, height / 2));
GeoVector[] norm = new GeoVector[4];
norm[0] = pln.Normal;
norm[1] = pln.Normal;
norm[2] = pln.Normal;
norm[3] = pln.Normal;
int[] ind = new int[6];
ind[0] = 0;
ind[1] = 1;
ind[2] = 2;
ind[3] = 0;
ind[4] = 2;
ind[5] = 3;
paintTo3D.Triangle(pnts, norm, ind);
paintTo3D.Blending(false);
paintTo3D.UseZBuffer(true);
}