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Nurbs curve curiosity


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I'm trying to create a nurbs curve that's a half circle w/ 10'R. My base curve for comparison is drawn with a half arc and converted to nurbs. So I used code with parameters so that every vertex in the oip looks like the base curve.

code:

h1 := CreateNurbsCurve(-120, 0, 0, true, 2);

AddVertex3D(h1, -120, 120, 0);

AddVertex3D(h1, 0, 120, 0);

AddVertex3D(h1, 120, 120, 0);

AddVertex3D(h1, 120, 0, 0);

NurbsSetWeight(h1, 0, 1, sin(Deg2Rad(45)));

NurbsSetWeight(h1, 0, 3, sin(Deg2Rad(45)));
[/code]

Except the curves don't match visually, even though everything in the OIP looks the same.

code:

h1 := CreateNurbsCurve(-120, 0, 0, false, 2);

AddVertex3D(h1, -120*sin(Deg2Rad(45)), 120*sin(Deg2Rad(45)), 0);

AddVertex3D(h1, 0, 120, 0);

AddVertex3D(h1, 120*sin(Deg2Rad(45)), 120*sin(Deg2Rad(45)), 0);

AddVertex3D(h1, 120, 0, 0);
[/code]

So I changed the code to the second sample--with byCtrlPts false--and now the curve matches the base curve visually. My question is why the first code doesn't match the base curve, even though every vertex looks the same in the OIP?

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