rem                            AREA_PGN.CDL

rem        Copy Right by International Technology Transfer Corp.
rem        revision 1.0 7/30/99   


rem        Area of Triangle Polygon Mesh



clear

:start
count = 0
s = 0
getmenu "Select Polygon","Single","Window","Polygon","All Dsp"
on ( @key + 3 ) goto exit,start,

selno=@key
if (selno==4)
	selno=7
if (selno==3)
	selno=4
if (selno==2)
	selno=3
getentm selno,nument

:polygon
count=count+1
if (count>nument)
	goto hyouji
getnext enttype,count
if (enttype!=6)
	goto polygon
if (@intdat[10]!=3)
	goto polygon
	
wx1 = @fltdat[0]
wy1 = @fltdat[1]
wz1 = @fltdat[2]
wx2 = @fltdat[3]
wy2 = @fltdat[4]
wz2 = @fltdat[5]
wx3 = @fltdat[6]
wy3 = @fltdat[7]
wz3 = @fltdat[8]
a = (wy2 - wy1) * (wz3 - wz1) - (wz2 - wz1) * (wy3 - wy1)
b = (wz2 - wz1) * (wx3 - wx1) - (wx2 - wx1) * (wz3 - wz1)
c = (wx2 - wx1) * (wy3 - wy1) - (wy2 - wy1) * (wx3 - wx1)
s = sqrt(a * a + b * b + c * c) / 2 + s
goto polygon

:hyouji
pause "Area of Triangle Polygon Mesh = %.3f", s

:exit