public SplineObject GenerateCircle(double rad)
{
const double TANG = 0.415;
double sn, cs;
int i, sub = 4;
SplineObject op = SplineObject.Alloc(sub * 2, SPLINETYPE.SPLINETYPE_BEZIER);
if (null == op || null == op.MakeVariableTag(C4dApi.Tsegment, 2))
{
C4dApi.blDelete_cs(op);
return(null);
}
op.GetDataInstance().SetBool(C4dApi.SPLINEOBJECT_CLOSED, true);
Segment seg = new Segment();
seg.closed = true;
seg.cnt = sub;
op.SetSegmentAt(0, seg);
op.SetSegmentAt(1, seg);
for (i = 0; i < sub; i++)
{
double angle = 2.0 * Math.PI * (double)i / (double)sub;
sn = Math.Sin(angle);
cs = Math.Cos(angle);
double3 vOuter = new double3(cs * rad, sn * rad, 0.0);
double3 vOuterTangentL = new double3(sn * rad * TANG, -cs * rad * TANG, 0.0);
double3 vOuterTangentR = -vOuterTangentL;
double3 vInner = vOuter * 0.5;
double3 vInnerTangentL = vOuterTangentL * 0.5;
double3 vInnerTangentR = -vInnerTangentL;
op.SetPointAt(i, vOuter);
Tangent outerTangent = new Tangent();
outerTangent.vl = vOuterTangentL;
outerTangent.vr = vOuterTangentR;
op.SetTangentAt(i, outerTangent);
op.SetPointAt(i + sub, vInner);
Tangent innerTangent = new Tangent();
innerTangent.vl = vInnerTangentL;
innerTangent.vr = vInnerTangentR;
op.SetTangentAt(i + sub, innerTangent);
}
op.Message(C4dApi.MSG_UPDATE);
return(op);
}