Along a line with varying intersections, mark midpoints between intersections

along a line with varying intersections, mark midpoints between intersections

Don’t know what you’re asking for here, but the “Between” object snap should do this (but one-by one), otherwise this should be something relatively simple to set up in Grasshopper, I think…

Quickie GH def and video (10.4 KB)


thanks. What I need is to indicate holes for pins to guide piano keys, these holes always being along the middle of each key lever. The lines I have indicate the edges of key, before these are sawn out of the glued-up panel, and their widths vary in a regular pattern repeating in each octave, in the narrow division behind the keyfronts, where the ivory or other coverings are glued, while at the rear of each key they all are of equal width. I can send the drawing I made, which is a lot easier than trying to put a keyboard layout in words. I have lines drawn for pin location, and these locations alternate in the same way the black and white keys are laid out. I don’t know the protocol for sending drawings. thanks again

points snap to the middle of the location line on some but not all keys, very few, and my questrion is what entity do you have to create so that the snap will recognize a section of a line as a place that has a middle.

Create temporary copies of the lines lines using Copy with the InPlace option. Use Divide with Split=Yes and number of segments = 2 to split the temporary lines in half. Midpoint snap to the middle of the split temporary lines.

Edit: If needed use Split to split the temporary line at the iintersections before using Divide.

this didn’t work, but that’s me. Tween surfaces worked adequately, but still the fact that a point location could snap midway on some few keys and then not is the issue for me

I lucked: building the tween point locations for one octave, then copying and pasting the result onto each octave, gave me deep satisfaction, and I have this forum to thank. might learn the thing…

tween curves works only between parallel lines

Hi Paul - if you did not get this sorted out, can you please export the curves you’re asking about and post the file here?


wonderful. Thanks. the holes to be drilled are indicated in the center of
each key lever at the front, in a point. The same pattern of natural and
accidental keys (sorry for nomenclature) the holes alternating back and
forth in a repeat pattern for each octave, must guide where the centers are
determined at the middle (sort of ) fulcrum hole shown in two nearly
parallel lines. The don’t share a tween surface line, the lines we see,
because the keys are splayed as indicated in the dimensions indicated.
What a job, but fun if I find the steps.
Thanks. Paul

this is the keyboard and its parts copied off to the left

grafkeypanel2017correctedarraytestemail.dwg (79.7 KB)

Hi Paul -Can you place a few points, even just approximately, so that I have some idea what I’m shooting for?


What i would do is use Split command to split the line with
all its intersecting curves and then mid snap will work on each segment.

After you have made the points you can copy them to clipboard and undo back to before you split the line and paste the points in, if you don’t want the line to remain split.

in excelsis

The points thus made can only be selected one by one? Getting this far in one day is a wonder, thanks

grafkeypanel2017correctedarraytestemail2.dwg (88.7 KB)

center points derived, not quite feasible to selct out the points in order to erase lines which located these points, but it doesn’t matter, since this area is covered over with a key button, as it’s called

Depending on how you created the geometry you could do this in a few different ways, like SelLast or SelPrev or SelCrv.
For example, if everything else is hidden and you create your points. SelLast will select these points and you can use Lock, then SelAll and Delete…