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Snapping with splines is incorrect #32
It seems that there is a precision issue / bug with the snap-to-intersection mode if splines are involved.
To reproduce, draw two splines, or a line segment and a spline, that intersect each other. Enter the snap-to-intersection mode and hover above the intersection point. In many cases, the intersection point indicated by Fifi will be displaced slightly from the actual intersection.
A test case is here; I placed orange marks on the intersection points that Ipe indicates. Here is a screenshot of the worst case I could find:
I'm using Ipe 7.1.10 on Kubuntu (Linux).
This is extremely annoying behavior. I'd like to spline to respect the intersections at the grid points that I tell it to.
This makes it next to impossible to draw horizontal and vertical lines to the axes at various points (unless I'm just a noob and there is some way to force lines to be horizontal and vertical!).
@derekwolfson I'm sorry, but I have no idea what you are trying to say. What does "I'd like to spline to respect the intersections at the grid points that I tell it to." mean?
To force horizontal and vertical lines, set the angular grid to 90 degrees, and turn on angular snapping (F8) or automatic snapping (F9), depending on your needs.
I don't understand what horizontal/vertical lines have to do with intersections of splines.
@otfried -- it is the same behavior that is mentioned above. Using this picture
I want the spline to respect that I want it to intersect at the grid point underneath the orange circle, even as I add more points to the spline.
However, the work-around you gave re: the horizontal and vertical lines allows me to have intersections of a spline and a line with webbing back to the axes, even when the intersection of the spline and the line are not on a grid-point:
Thanks for dealing with my n00bness.