Quadrant snap not accurate


Quadrant snap is not always accurate. Has been like this for a while. See screenshot for example. The quadrant snap hover over is actually not showing up on the screenshot. Degree 5 curve.

Hope this can be fixed. Thank you.

Can you please post the Rhino file?

I think I can repeat it.
Windows Rhino has the same problem.

Reported as RH-30431
Thanks for sending it in.

Turns out it is only a problem on single span degree 5 (6 points) and degree 7 (8 point) curves. Quadrant on a degree 9 single span curve seems OK.

This has been fixed and tested for V6.
It looks like the fix is too risky for V5 as it will likely break other things.

Here’s a note from the developer:
“This is a side effect of the method used in IsEllipse() test for determining if the curve has a shape of an ellipse. It samples the curve at six points, and checks if an ellipse through those six points can be built, and then checks each curve span at 6 points to see if they are within tolerance to the ellipse.
In this case the curve wiggles pretty far from the exact ellipse, but is very near at the 6 tested points where it crosses the ellipse. Attached “BumQuad_with_clarifying_ellipse.3dm” shows the ellipse. It also explains why the quad point is so far from the curve.”

Thanks, good to hear it will be fixed for V6.