[metapost] Problem with quartercircle

[Pétiard François]

Taco Hoekwater a écrit le 15/02/2006 19:39 :
> Pétiard François wrote:
> 
>> Why the second quartercircle isn't cut after z1 ?
> 
> 
> The point z1 is not *on* the path qd, but only coincident with it.
> 
> Do it like this:
> 
>   z1=point(xpart (qd intersectiontimes((0,0)--(4cm,4cm)))) of qd;
> 
> Cheers, Taco
> 

Sorry, but I don't understand ; consider the following file :

prologues:=1;

beginfig(1);
path qc,qd,qe,qf;

qc:=quartercircle scaled(3.05cm);
z0=qc intersectionpoint((0,0)--(3cm,3cm));
labels(0);
draw qc cutafter(z0) withcolor blue;  %OK

qd:=quartercircle scaled(3cm);
z1=qd intersectionpoint((0,0)--(3cm,3cm));
labels(1);
draw qd cutafter(z1);   %Not correct

qe:=quartercircle scaled(5.11cm);
z2=qe intersectionpoint((0,0)--(3.00009cm,3.0001cm));
labels(2);
draw qe cutafter(z2) withcolor red;  %OK

qf:=quartercircle scaled(5cm);
z3=qf intersectionpoint((0,0)--(3.00009cm,3.0001cm));
labels(3);
draw qf cutafter(z3);  %Not correct

endfig;
end;


Why qc and qe are cut, and not qd and qf ?

F. Pétiard

-- 
petiard.francois at free.fr