rem        *********************  Ang_2Ln.cdl ***********************

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


rem        Angle between 2 lines

rem        Procedure
rem        1. Select 1st Line
rem        2. Select 2nd Line
rem        3. Display angle
rem        ********************************************************************


clear
:start
getent "Select First Line",enttype
	on (@key + 3) goto exit,start,
	if (enttype!=2)
		goto start
	x1 = @fltdat[0]
	y1 = @fltdat[1]
	z1 = @fltdat[2]
	x2 = @fltdat[3]
	y2 = @fltdat[4]
	z2 = @fltdat[5]
	
	f1 = x2 - x1
	g1 = y2 - y1
	h1 = z2 - z1
	
	
:second
	getent "Select Second Line",enttype
	on (@key + 3) goto exit, start, second, 
	if (enttype!=2)
		goto second
	
	x3 = @fltdat[0]
	y3 = @fltdat[1]
	z3 = @fltdat[2]
	x4 = @fltdat[3]
	y4 = @fltdat[4]
	z4 = @fltdat[5]
	
	f2 = x4 - x3
	g2 = y4 - y3
	h2 = z4 - z3

	r1 = sqrt(f1 * f1 + g1 * g1 + h1 * h1)
	r2 = sqrt(f2 * f2 + g2 * g2 + h2 * h2)

rem     from following equation
rem     cos(angle) = (f1*f2 + g1*g2 + h1*h2) / (r1 * r2)

	ang = acos( (f1*f2 + g1*g2 + h1*h2) / (r1 * r2) )
	if (ang>90)
		ang = 180 - ang

	pause "Angle= %.3f", ang
	goto start
:exit