%!

% set units to inches
72 72 scale
0.01 setlinewidth
2 2 translate

% draw the boundary of the picture
newpath
0 0 moveto
4 0 lineto
4 3 lineto
0 3 lineto
closepath
stroke

% restrict all subsequent drawing to inside that boundary by clipping
newpath
0 0 moveto
4 0 lineto
4 3 lineto
0 3 lineto
closepath
clip

% draw the water in the pool
newpath
0 0 moveto
4 0 lineto
4 1.5 lineto
0 1.5 lineto
closepath
0.8 0.9 1 setrgbcolor
fill

% move the origin to the centre of the pool
2 1.5 translate

/depth 1 def
/A -20 def
/dA 20 def

% draw 3 rays at angles -20, 0, 20, 
% incrementing A each time through the loop

3 {

1 0 0 setrgbcolor
newpath
0 depth -1 mul moveto
A sin A cos div 0 lineto
/s A sin 1.33 mul def
/c 1 s s mul sub sqrt def
s 2 mul c 2 mul rlineto
stroke

/A A dA add def

} repeat

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