;************************************************* ; tdpack_6.ncl ;************************************************ load "\$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl" begin ; ; Set the desired minimum and maximum values of U, V, and W. ; umin = -1 vmin = -1. wmin = -1. umax = 1. vmax = 1. wmax = 1. ; ; Set the desired values of parameters determining the eye position. ; ang1 is a bearing angle, ang2 is an elevation angle, and rmul is a ; multiplier of the length of the diagonal of the data box, specifying ; the distance from the center of the box to the eye. ; ang1 = -35. ang2 = 25. rmul = 2.9 ; ; Define the number of points to be used in defining the curve. ; ncrv = 1001 ; ; Define the conversion constant from degrees to radians. ; dtor = .017453292519943 ; ; Define labels for the edges of the box. ; unlb = " -1 -.8 -.6 -.4 -.2 0 .2 .4 .6 .8 1 " vnlb = " -1 -.8 -.6 -.4 -.2 0 .2 .4 .6 .8 1 " wnlb = " -1 -.8 -.6 -.4 -.2 0 .2 .4 .6 .8 1 " uilb = "U Coordinate Values" vilb = "V Coordinate Values" wilb = "W Coordinate Values" ; ; Define the curve. ; ii = ispan(0,ncrv-1,1)*1. xcrv = .75*cos(dtor*(ii/(ncrv-1))*720.) ycrv = .75*sin(dtor*(ii/(ncrv-1))*720.) zcrv = -.75+1.5*ii/(ncrv-1) ; ; Open workstation. ; wks = gsn_open_wks("ps","tdpack") ; ; Use a 25-degree (instead of the default 20-degree) field of view. ; tdsetp ("FOV",25.) ; ; Make TDPACK characters a bit bigger. ; tdsetp ("cs1",1.25) ; ; Find the midpoint of the data box (to be used as the point looked at). ; umid = .5*(umin+umax) vmid = .5*(vmin+vmax) wmid = .5*(wmin+wmax) ; ; Determine the distance (R) from which the data box will be viewed and, ; given that, the eye position. ; r = rmul*sqrt((umax-umin)^2+(vmax-vmin)^2+(wmax-wmin)^2) ueye = umid+r*cos(dtor*ang1)*cos(dtor*ang2) veye = vmid+r*sin(dtor*ang1)*cos(dtor*ang2) weye = wmid+r*sin(dtor*ang2) ; ; Initialize TDPACK. ; tdinit ((/ueye,veye,weye/),(/umid,vmid,wmid/),(/umid,vmid,wmid+r/),0.) ; ; Draw labels for the axes. ; tdlbls (wks,(/umin,vmin,wmin/),(/umax,vmax,wmax/),(/unlb,vnlb,wnlb/), \ (/uilb,vilb,wilb/),1) ; ; Draw the sides of the box that could be hidden. ; tdgrds (wks,(/umin,vmin,wmin/),(/umax,vmax,wmax/),(/.1*(umax-umin), \ .1*(vmax-vmin), \ .1*(wmax-wmin)/),12,1) ; ; Draw the curve in pieces, with an arrowhead on each one. ; do j=1,ncrv-1,100 ; ; Compute the number of points on this piece. ; npts=min((/100,ncrv-j+1/)) j1 = j-1 j2 = j1 + npts ; ; Draw a curve. The fourth argument says whether or not there is to be ; an arrowhead on the end of the curve and, if so, how many points are ; to be used in drawing its conical base (48, in the third case) and how ; many of those points are to be connected to the tip (12, in the third ; case). ; ; tdcurv (wks,xcrv(j1:j2),ycrv(j1:j2),zcrv(j1:j2),0,.2,.1) ; tdcurv (wks,xcrv(j1:j2),ycrv(j1:j2),zcrv(j1:j2),1,.2,.1) ; tdcurv (wks,xcrv(j1:j2),ycrv(j1:j2),zcrv(j1:j2),12048,.2,.1) tdcurv (wks,xcrv(j1:j2),ycrv(j1:j2),zcrv(j1:j2),12048,.2,.1) end do ; ; Draw the sides of the box that could not be hidden. ; tdgrds (wks,(/umin,vmin,wmin/),(/umax,vmax,wmax/),(/.1*(umax-umin), \ .1*(vmax-vmin), \ .1*(wmax-wmin)/),12,0) ; ; Advance the frame. ; frame(wks) end