You may remember that I did some posts around splines for AutoCAD 2011. If you believed that a lot of progress was made, you are right. However, there were a couple of aspects we wanted to enhance. The most important one was to get periodic splines in AutoCAD.
So what does this mean to you? Let’s say you created a spline in AutoCAD 2011 (or previous), and came up with something symmetric. I just created one in AutoCAD 2012 using the corners of this square. Note that I can close with right click menu, and not have to define end tangency.
If I select the spline and show its properties, I can see 4 control vertices.
In the past, you would have seen 5 control vertices. Nothing shocking until you wanted to rebuild the spline. At that point, the shape would become asymmetrical, with a concentration of CVs (control vertices) around the place where you closed the spline.
As you can see, in AutoCAD 2012, even after rebuilding the spline, we get the right shape and the right amount of control vertices (in the right place).
This will also directly impact (in a good way) any shape you create based on these periodic splines. I just copied the spline along the Z axis, and scaled one of them, so as to get a nice loft. By the way, have you noticed that the loft is giving a real time preview as you select cross sections? This is just another enhancement in AutoCAD 2012.
After getting the loft, I just made another exercise. By converting the loft into a NURBS surface, and showing the CVs, you can see the same symmetry from the splines.