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Ray-casting algorithm: Difference between revisions
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exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
in$out: procedure expose point. poly.; parse arg p;
do side=1 to poly.0 by 2; #=#+intersect(p,side); end /*side*/
return # //
/*──────────────────────────────────────────────────────────────────────────────────────*/
intersect: procedure expose point. poly.; parse arg ?,s; sp=s+1
epsilon='1e' || (-digits()%2); infinity="1e" || (digits() *2)
Px=point.?.x; Ax=poly.s.x; Ay=poly.s.y
Py=point.?.y; Bx=poly.sp.x; By=poly.sp.y /* [↓] do a swap.*/
if Ay>By then parse value Ax Ay Bx By with Bx By Ax Ay
if Py=Ay | Py=By then Py=Py + epsilon
if Py<Ay | Py>By | Px>max(Ax,Bx) then return 0
if Px<min(Ax,Bx) then return 1
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if Ax\=Px then m_blue=(Py-Ay) / (Px-Ax)
else return 1
return m_blue >= m_red
/*──────────────────────────────────────────────────────────────────────────────────────*/
points: wx=0; wy=0; do j=1 for arg(); parse value arg(j) with xx yy
call value point.0, j-1
return
/*──────────────────────────────────────────────────────────────────────────────────────*/
poly: @='POLY.'; parse arg Fx Fy
n=0
do j=1 for arg(); n=n+1;
call value @ || n'.X', xx ; call value @ || n".Y", yy
if n//2 then iterate; n=n+1
call value @ || n'.X', xx ; call value @ || n
n=n+1
call value @ || n'.X', Fx; call value @ || n".Y", Fy; call value @'0',n
return /*POLY.0
/*──────────────────────────────────────────────────────────────────────────────────────*/
test: say; do k=1 for point.0;
say right(' ['arg(1)"] point:", 30),
right( right(point.k.x, wx)', 'right(point.k.y, wy),
right( word('outside inside', in$out(k)+1), 7)
end /*k*/
return</lang>
'''output'''
<pre>
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