Bouncy maze

levels=5
fastgraphics
graphsize 600,600
clg
dim board$ (16,levels)
board$ [0,0]= "xxxxxxxxxxxxxxxxxxxxxxxxxx"
board$ [1,0]= "x                        x"
board$ [2,0]= "x                        x"
board$ [3,0]= "x    xxxxxxxxxxxxxxxx    x"
board$ [4,0]= "x                   x    x"
board$ [5,0]= "x                   x    x"
board$ [6,0]= "xxxxxxxxxxxxxxx     x    x"
board$ [7,0]= "x                   x    x"
board$ [8,0]= "x                   x    x"
board$ [9,0]= "x         xxxxxxxxxxx    x"
board$ [10,0]="x         x         x    x"
board$ [11,0]="x         x         x    x"
board$ [12,0]="x    x    x    x    x    x"
board$ [13,0]="x              x         x"
board$ [14,0]="x              x         x"
board$ [15,0]="xxxxxxxxxxxxxxxxxxxxxxxxxx"
font "courier" ,25,200
#initial speed and position
px=100
py=140
ax=2
ay=2
# main loop
do
for y =  0 to 15
text 0,y*25,board$[y,0]
next y

circle px,py,10
refresh
clg
if mid(board$[floor(py/25-.2),0],ceil(px/19+0.4),1)="x" then
ax=-ax
end if
if mid(board$[floor(py/25-.2),0],ceil(px/19+0.2),1)="x" then
ax=-ax
end if
if mid(board$[floor(py/25-.1),0],ceil(px/19+0.3),1)="x" then
ay=-ay
end if
if mid(board$[floor(py/25-.3),0],ceil(px/19+0.3),1)="x" then
ay=-ay
end if
px=px+ax
py=py+ay
until 3=2