rem                            L_Para.cdl


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


rem        Parallel Line


rem        ********************************************************************
rem         Create Parallel Line

rem        1. Select Line
rem        2. Select Position to draw Line
rem        3. Create Parellel Line
rem        ********************************************************************

clear
defopt = 2

:start
	getent "Select Line",enttype
	on (@key + 3) goto exit, start, start,
	if (enttype!=2)
		goto start

	x1 = @fltdat[0]
	y1 = @fltdat[1]
	z1 = @fltdat[2]
	x2 = @fltdat[3]
	y2 = @fltdat[4]
	z2 = @fltdat[5]

	f = x2 - x1
	g = y2 - y1
	h = z2 - z1

:pos
	getpos "Indicate Position",defopt
	on (@key + 3) goto exit, start, pos, 
	defopt=@key

	x0 = @xworld
	y0 = @yworld
	z0 = @zworld


	t = (f * (x1-x0) + g * (y1-y0) + h * (z1-z0))/(f*f + g*g + h*h)

	x3 = x0 + f * t
	y3 = y0 + g * t
	z3 = z0 + h * t

	t = (f * (x2-x0) + g * (y2-y0) + h * (z2-z0))/(f*f + g*g + h*h)

	x4 = x0 + f * t
	y4 = y0 + g * t
	z4 = z0 + h * t

	line x3, y3, z3, x4, y4, z4

	redraw
	goto start
:exit