How to draw a Clothoide?

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TheEnglishPatient
Active Member
Posts: 35
Joined: Sun Feb 19, 2012 12:56 pm

How to draw a Clothoide?

Post by TheEnglishPatient » Fri Apr 27, 2018 9:28 am

Does anyone know how to draw a proper Clothoide (Cornu-Spiral)?

I am particularly interested in the 'flat' bit around the origin, say up to 30 degrees, as this is commonly used as transition element in the geometry of road or track design between straights/and or circular arcs.

I had a look at the Spiral script example, but I fear the implementation of solving elliptical Integrals in QCAD's script language is currently beyond me.

Does anyone have something off the peg? I think it should be sufficient to specify start radius (curvature), end radius, length, and maybe a sample interval to get some sort of polyline approximation.

Thanks in advance for any help.

CVH
Premier Member
Posts: 764
Joined: Wed Sep 27, 2017 4:17 pm
Location: Belgium; Antwerp

Re: How to draw a Clothoide?

Post by CVH » Mon May 14, 2018 3:43 pm

https://en.wikipedia.org/wiki/Euler_spiral for the math.
Misc\Examples\MathExamples\ExMathSpiral.js as base for a script.

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