双箭头

hbghlyj

How to define a custom ArrowHead in Asymptote?
In this figure, in order to draw "DoubleHead", I made a precedure to draw SimpleHead repetitively, but can we define an ArrowHead "DoubleHead", similar to \draw[->>] in TikZ?

Related
Asymptote FAQ - Section 5 Questions about arrows
Q5.1 How do I draw two arrows at arbitrary positions along a path? Assuming that at least one of the arrowheads is to be filled, you can do this: ...

hbghlyj

在Aops community / Aops blog使用的TeXeR支持的Asymptote, 自动import olympiad.asy和CSE5.asy

The Asymptote CSE5 package is another package that is supported on the AoPS forum

在olympiad中有一个pathticks可以画1#的多重箭头

查看源码

1. // A picture marking a path g with n ticks spaced spacing apart, with length s in ps points
2. // such that the middle tick mark (or one of the two if n is even) is normal to g
3. // and located r of the way along path g:
4. picture pathticks(path g, int n=1, real r=.5, real spacing=6, real s=8, pen p=currentpen)
5. {
6.         picture pict;
7.         pair A,B,C,direct;
8.         real t,l=arclength(g), space=spacing*markscalefactor, halftick=s*markscalefactor/2, startpt;
9.         if (n>0)
10.         {  
11.                 direct=unit(dir(g,arctime(g,r*l)));  
12.                 startpt=r*l-(n-1)/2*space;  
13.                 for (int i=0; i<n; ++i)  
14.                 {  
15.                         t=startpt+i*space;  
16.                         B=point(g,arctime(g,t))+(0,1)*halftick*direct;  
17.                         C=B+2*(0,-1)*halftick*direct;  
18.                         draw(pict,B--C,p);  
19.                 }
20.         }
21.         return pict;
22. }

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在geometry.asy有一个markangle用来标角, 见tex.stackexchange.com/questions/597937
而在olympiad.asy有anglemark, 应该是功能扩展的. 和rightanglemark用来标直角. 例如
filldraw(anglemark((5,0),(0,0),(3,4)),green,red+linewidth(1));