Hi, you can see in the top view two closed planar curves. The two curves are positioned in a diagonal axis. I am trying to find the two external tangents that are connecting the two curves. The problem is that I just can find tangent components that are relating to circles. I know that the two curv…

First of all, thank you! Unfortunatly I cannot simplify the curves. I need a more precise result, relating to my original curves.

Maybe there is a native GH compnent but if no, here is simple code that does it: CurveCurveTangent.gh (6.4 KB) [Canvas%20at%2019%3B49%3B07] (RhinoCommon)

Thanks for your work. Because I am not that familiar with coding, I hope that you can explain the process behind the code. Maybe this can help me to understand the process and trying to translate it into native components. More over can you explain you Prm1 and 2 Value?

Here is the link to the method that does the job: Line.TryCreateBetweenCurves Method Creates a line segment between a pair of curves such that the line segment is either tangent or perpendicular to each of the curves. Most of GH components are wraps around c…

Quick approximate solution, divide your curves into many, many points (like, thousands), put all those points into a single list and use Convex Hull on it. The hull should contain lots of very short segments but two long ones. That’s your tangent lines.

This is the same method of @RadovanG using Python ,with care to avoid intersections when curves are not flipped right tangent curves.gh (11.7 KB) [image]

[image] RadovanG: curve parameter on each curve If you are after absolute performance (of course you are) I would suggest to exploit PlanB: get “start” circles, do the classic tangents + end prox pts etc etc … and thus limit the forward/backward recursion considerably (for big N of curves has…

I made this component with Python ( my first component :smile: ) Right now after some tests it work fine Tangent Lines.ghpy (37 KB)

congrats! nice work! although, I just noticed: at 0:14 it should have produced a second tangent and it didn’t. Back to work you lazy scallywag!!! :stuck_out_tongue: :stuck_out_tongue: :stuck_out_tongue:

There’d be two tangents at 0:14, you want both, the shortest one, the longest one, the inner most one, the outermost one, the one which doesn’t intersect the rest of the curve, … lot of decisions to be made here.

How to find external tangents between two closed planar curves (not circles)?

Grasshopper

markz October 19, 2019, 3:58am 20

works pretty well for multiple curves

Tan on single curve

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How to find external tangents between two closed planar curves (not circles)?

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