SYNOPSISCALL DANDR (NV,NW,ST1,LX,NX,NY,IS2,IU,S,IOBJS,MV)
STATUSThis routine is part of the obsolete Isosrfhr utility. Isosrfhr has been replaced by the Isosurface utility. To see the Isosurface utility overview man page, type "man isosurface".
- (an input expression of type INTEGER) defines the range to be used for the V dimension of the 3-D UVW grid.
- (an input expression of type INTEGER) defines the range to be used for the W dimension of the 3-D UVW grid.
- (an input array of type REAL) used as scratch work space. It must be dimensioned at least of size NV*NW*2 words.
- (an input array of type INTEGER) which is the first dimension of array IS2. It must be of a length to hold NX bits. On a 64 bit machine it would be LX=(NX-1)/64+1.
- (an input expression of type INTEGER) defines the range of cells in the X-direction of the XY pixel model of the image plane. A silhouette of the parts of the picture processed so far is stored in this model. Lines to be drawn are tested for visibility by examining the silhouette. Lines in the silhouette are hidden. Lines out of the silhouette are visible. The solution is approximate because the silhouette is not formed exactly. See IS2.
- (an input expression of type INTEGER) defines the range of cells in the Y-direction of the XY pixel model of the image plane. NY is also the second dimension of array IS2.
(an input array of type INTEGER) which holds the XY pixel
model of the image plane. It is dimensioned LX by NY.
The pixel model contains NX by NY elements. The sizes of
NX and NY vary with the choice of options. For example,
if hidden lines are drawn, NX and NY (and LX) can be smaller than
when hidden lines are not drawn. If some visible lines
are not drawn, NX and NY (and LX) must be made larger.
As a guide, some examples which have been adequate are:
GIVEN USE NU NV NW NX NY -------------------------------- 100 100 60 200 200 60 60 60 110 110 40 40 40 75 75
- (an input expression of type INTEGER) defines the unit number of a scratch file for the package. ST1 will be written NU times on this file.
(an input array of type REAL, dimensioned 4) contains
the world coordinates of the area where the picture
is to be drawn. That is, all plotting
coordinates generated will be bounded as
follows: X coordinates will be between S(1)
and S(2), Y coordinates will be between S(3)
and S(4). To prevent distortion, have
S(2)-S(1) = S(4)-S(3).
All coordinates should be in a range between 10. and 1010.
(an input array of type INTEGER) which describes the
objects to be drawn in VW space. It is of size
NV by NW. The actual first dimension of IOBJS in the
calling program is MV.
Entry DANDR is called NU times to process any object contours in the VW cross sections defined by IOBJS. Slabs are processed from back to front such that on the I-th call to DANDR, the slab at U = NU+1-I is processed. IOBJS(J,K) = 1 if any object contains the point (NU+1-I,J,K) and IOBJS(J,K) = 0 otherwise.
- (an input expression of type INTEGER) defines the actual first dimension of the array IOBJS in the calling program. When plotting all of IOBJS, NV = MV.
USAGEEntries DANDR and DANDR must be used in tandem to create a plot. First call entry DANDR to create a set of 2-D perspective planes which are output to a scratch file. Then, in the calling program you must loop over the U dimension of UVW space starting at the last slab, NU, and moving forward to slab 1. Initially set all elements of IOBJS to zeros. Then, at all locations (J,K) where the surface of an object would appear, set IOBJS(J,K) = 1. When IOBJS(J,K) has been defined for that VW slab (U = NU - I + 1), call the entry DANDR, which draws any object contours based on the 2-D perspective defined for that slab.
An Isosrfhr example of the logical structure of a program follows:
C Entry DANDR writes NU 2-D perspective planes, ST1(NV,NW,2), C of the UVW grid, viewed from the position EYE, to a scratch file. C CALL DANDR(EYE,NU,NV,NW,ST1,LX,NY,IS2,IU,S) C C NU is the extent of the U dimension. C DO 1 IBKWDS = 1,NU I = NU+1-IBKWDS C C You must define the presence of the objects at each VW grid point for C all slabs in the U direction. Ones are used to indicate the presence C of an object. Zeros indicate no object. C C IF (OBJ.EQ.YES) IOBJS(J,K) = 1 C IF (OBJ.EQ.NO) IOBJS(J,K) = 0 C C DANDR reads ST1(NV,NW,2) for slab I. C 1 CALL DANDR(NV,NW,ST1,LX,NX,NY,IS2,IU,S,IOBJS,MV)
EXAMPLESUse the ncargex command to see the following relevant examples: tisohr
ACCESSTo use DANDR load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in that order.
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University Corporation for Atmospheric Research
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