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Anonymous
en respuesta a: jimbir

Hi jimbir, 

 

For your case, it may be best to plot the final control vertex and then re-adjust the previous vertices to fit the curve close to what you were trying to match. 

 

When drawing NURBS (non-rational uniform b-splines), there is a difference in how the curvature of the spline is calculated based on where the CV (control vertices) are but also whether the CV is the end (sometimes called a knot) of the spline. When you are plotting CVs for a spline, the computer will calculate the curvature of the spline assuming that the next CV you place is not the endpoint. This is because each CV is weighted in a sense based on the two adjacent CVs at least. Imagine if you had a long, thin strip of wood that you had to bend around pegs on pegboard. The curvature of the strip of wood changes depending on whether it is bent around a peg versus whether it is the end of the strip of wood that is affixed

 

Leeminardi gave a really great answer that covers the fundamentals of NURBS modelling/drafting. In the context of drafting curvy objects precisely, it will help a lot to take the time to understand some of the quirks of this workflow. 

 

I hope this helps! If I got anything wrong, please correct me.