#!/usr/local/bin/yabasic
rem This program was coded by Hermang Mansilla
rem and released under GPL license :-)
rem This Program draws  rotating polygons
dim x(6),y(6), X(6),Y(6)
R=90
rem origin coordinats
OX=R+6:OY=R+6
rem size of Window
SX=3*R:SY=3*R
open window SX,SY
kk=0.15
label inicio
input "Number of sides (2<N<7)=" N
if N>6 or N<3 then end fi
clear window
k=N-2
rem pone cordenad en x(), y()
for i=0 to k+1
x(i)=R*sin(2*pi*i/(k+2))
y(i)=R*cos(2*pi*i/(k+2))
gosub transfcor
rem The following print lines are for diagnostic, you can comment them
print
print "cordenadas (x,y)=",x(i),y(i),"-->(",X(i),",",Y(i),")"
next i
gosub dibuja
goto inicio
end 

label transfcor
X(i)=x(i)+OX
Y(i)=OY-y(i)
if Y(i)<0 then Y(i)=-Y(i) endif
return

label dibuja

for i=1 to 10+5*k
X(k+2)=X(0):Y(k+2)=Y(0)
for j=0 to k+1
X1=X(j):Y1=Y(j)
X2=X(j+1):Y2=Y(j+1)
line X1,Y1 to X2,Y2
X(j)=X(j)+kk*( X(j+1)-X(j) )
Y(j)=Y(j)+kk*( Y(j+1)-Y(j) )
next j
next i
return