00001
00002 c
00003 c Copyright (c) 1986,1987,1988,1989,1990,1991,1992,1993,
00004 c by Steve McMillan, Drexel University, Philadelphia, PA.
00005 c
00006 c All rights reserved.
00007 c
00008 c Redistribution and use in source and binary forms are permitted
00009 c provided that the above copyright notice and this paragraph are
00010 c duplicated in all such forms and that any documentation,
00011 c advertising materials, and other materials related to such
00012 c distribution and use acknowledge that the software was developed
00013 c by the author named above.
00014 c
00015 c THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
00016 c IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
00017 c WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
00018 c
00019
00020
00021 subroutine arrow(xtail,ytail,xhead,yhead,mode)
00022 save
00023 c
00024 c Draw arrow from (x,y)-tail to (x,y)-head.
00025 c If mode = 0, x and y are user units.
00026 c If mode = 1, x and y are in inches.
00027 c
00028 common/scales/xl,xr,dinchx,ybot,ytop,dinchy,rlen,slen
00029 data open,pi/.5236,3.141593/head_size/-1.0/
00030
00031 if(mode.eq.0)then
00032 rtail=(xtail-xl)*dinchx
00033 stail=(ytail-ybot)*dinchy
00034 dr=(xhead-xtail)*dinchx
00035 ds=(yhead-ytail)*dinchy
00036 else
00037 rtail=xtail
00038 stail=ytail
00039 dr=xhead-xtail
00040 ds=yhead-ytail
00041 end if
00042
00043 c Draw the shaft of the arrow.
00044
00045 theta=atan2(ds,dr)
00046 call plot(rtail,stail,3)
00047
00048 rhd=rtail+dr
00049 shd=stail+ds
00050 call plot(rhd,shd,2)
00051
00052 c Draw the point, scaled to shaft size if not otherwise specified.
00053
00054 alpha=theta+pi-open
00055 shaft=sqrt(dr*dr+ds*ds)
00056
00057 if (head_size.le.0.0) then
00058 if(shaft.gt.1.)then
00059 point=.15*shaft
00060 else if(shaft.lt..5)then
00061 point=max(.05,.2*shaft)
00062 else
00063 point = 2.*(shaft-.5)*.15*shaft
00064 & + 2.*(1.-shaft)*max(.05,.2*shaft)
00065 end if
00066 else
00067 point = head_size
00068 end if
00069
00070 r=rhd+point*cos(alpha)
00071 s=shd+point*sin(alpha)
00072 call plot(r,s,2)
00073 call plot(rhd,shd,3)
00074 alpha=alpha+2.*open
00075 r=rhd+point*cos(alpha)
00076 s=shd+point*sin(alpha)
00077 call plot(r,s,2)
00078
00079 return
00080
00081 entry set_arrow_head(size)
00082
00083 c Specify arrowhead size, in "inches".
00084
00085 head_size = size
00086
00087 end
