Artlet2Dの円弧のバグ

#include "a2d.hsp"
; 0
alCreateImage 0, 640, 480
if stat = -1 : dialog "GDI+ " : end
d = 600.0 //
// s0=1.5200
f = d*0.9 //
px = -d/2 + 20
py = -d/2 + 20
r0 = 0.0 //
r1 = 90.0 //
s0 = 0.0 //
// s0 = 1.5
r0 -= s0
r1 += s0*2
//
alColor 0, 0,0, 255
alPenWidth 1
alDrawLine px+d/2,py+d/2, px+d*2,py+d/2
alDrawLine px+d/2,py+d/2, px+d/2,py+d*2
//
alColor 255, 0,0, 127
alPenWidth f
alDrawArc px,py, d,d, r0,r1
alCopyImageToScreen 0, 0
redraw
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