Draws perimeters, ticks, and grid lines on the six sides of a box (for use with selected TDPACK routines).
Available in version 4.3.1 and later.
procedure tdgrds ( wks  : graphic, uvwmin  : float, uvwmax  : float, uvwstep  : float, igrt  : integer, ihide  : integer )
Float arrays of 3 elements each specifying the minimum and maximum coordinate values defining the data box in 3-space.uvwstep
Float array of 3 elements specifying step sizes between ticks or grid lines in the U direction, the V direction, and the W direction, respectively. If one of these values is less than or equal to zero, the ticks or grid lines in the associated direction are omitted.igrt
An integer input value of the form 10*igrn+igrf, where igrn is a value specifying what to draw on the near sides of the box and igrf is a value specifying what to draw on the far sides of the box, where "near" and "far" are as defined by the current line of sight.
Each of igrn and igrf can have one of the values 0 (draw nothing), 1 (draw just a perimeter), 2 (draw a perimeter with inward-pointing ticks), or 3 (draw a perimeter with a grid). For example, to draw grids on the far side of the box and just perimeters on the near sides of the box, use igrt = 13.ihide
An integer input value set to 0 to draw only those sides of the box that cannot be hidden by something inside the box or to 1 to draw only those sides of the box that can be hidden by something inside the box.
Standard operating procedure is to call tdgrds before drawing surfaces inside a box, with ihide set to 1, and then call it again after drawing surfaces inside a box, with ihide set to 0.
This routine is part of the low-level TDPACK package, which is a group of Fortran and C callable routines for projecting objects from a 3-dimensional coordinate system having U, V, and W axes to a 2-dimensional projection plane having X and Y axes and/or for drawing the projections of those objects. This can be referred to somewhat loosely as "drawing objects in three dimensions".
Please see the documentation on TDGRDS for a full description of this procedure.
Grid drawing routines: tdgrid
The following code produces a sample 3D scatter plot:
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl" ; ; Function for generating random data. ; function dsrnd1(ifrst,nextn) begin MPLIER = 16807 MODLUS = 2147483647 MOBYMP = 127773 MOMDMP = 2836 JSEED = 123456789 if (ifrst .eq. 0) then nextn = JSEED ifrst = 1 end if hvlue = nextn / MOBYMP lvlue = nextn % MOBYMP testv = MPLIER*lvlue - MOMDMP*hvlue if (testv .gt. 0) then nextn = testv else nextn = testv + MODLUS end if return((1.*nextn)/(1.*MODLUS)) end begin N = 1331 NEAREST = 500 MTRI = 150000 FARTHER = N - NEAREST ; ; Create our input and work arrays. ; x = new(N,float) y = new(N,float) z = new(N,float) rtri = new((/MTRI,10/),float) rtwk = new((/MTRI,2/),float) ; ; Fill up the dummy input arrays. ; ifrst = 0 nextn = 0 do i = 0,N-1 x(i) = dsrnd1(ifrst,nextn) y(i) = dsrnd1(ifrst,nextn) z(i) = dsrnd1(ifrst,nextn) end do ; ; Specify the reference point from which we want to find the NEAREST ; nearest points. ; px = 0.5 py = 0.5 pz = 0.5 wks = gsn_open_wks("ps","scatter") ; ; Set some TDPACK parameters and initialize. These four are viewport ; specifiers. ; tdsetp("VPB", 0.09) tdsetp("VPT", 0.99) tdsetp("VPL", 0.11) tdsetp("VPR", 1.00) tdinit((/4.6, 3.0, 3.3/), (/0.5, 0.5, 0.5/), (/0.5, 0.5, 2.7/), 0.) ; ; Set up some colors using the standard TDPACK entry for that. ; tdclrs(wks, 1, 0., 0.8, 8, 37, 8) ; ; Define style indices for shades of gray, green, and red. ; tdstrs(1, 8, 37, 8, 37, 1, 1, 0, 0.05, 0.05, 0.) tdstrs(3, 8, 37, 68, 97, 1, 1, 0, 0.05, 0.05, 0.) tdstrs(4, 8, 37, 98, 127, 1, 1, 0, 0.05, 0.05, 0.) ; ; Store the indices of the nearest points in npts and the complement ; of that set (with respect to the entire input dataset) in mpts. ; npts = new(NEAREST,integer) mpts = new(FARTHER,integer) npts(0) = shgetnp(px,py,pz,x,y,z,0) do i=2,N if (i .le. NEAREST) then npts(i-1) = shgetnp(px,py,pz,x,y,z,1) else mpts(i-1-NEAREST) = shgetnp(px,py,pz,x,y,z,1) end if end do ; ; Plot the near points in green. ; ntri = 0 dotsize = 0.02 do i = 0, NEAREST-1 tdmtri(-5, (/x(npts(i)-1), y(npts(i)-1), z(npts(i)-1)/), dotsize, \ rtri, ntri, 4, (/0.,0.,0./),(/1.,1.,1./)) end do ; ; Plot the farther points in gray. ; do i = 0, FARTHER-1 tdmtri(-5, (/x(mpts(i)), y(mpts(i)), z(mpts(i))/), dotsize, \ rtri, ntri, 1, (/0.,0.,0./),(/1.,1.,1./)); end do ; ; Mark the reference point in red. ; tdmtri(-5,(/px,py,pz/),1.2*dotsize,rtri,ntri,3,(/0.,0.,0./),(/1.,1.,1./)) ; ; Order and draw triangles. ; itwk = tdotri(rtri, ntri, rtwk, 0) tddtri(wks,rtri, ntri, itwk) ; ; Draw a box around the perimeter. ; tdgrds(wks,(/0., 1., 0./), (/1., 0., 1./), (/-1., -1., -1./),11,0) tdgrds(wks,(/0., 1., 0./), (/1., 0., 1./), (/-1., -1., -1./),11,1) frame(wks) endAlso, see examples 3, 4, and 6 on the three-dimensional graphics applications page.