gevtm - Evaluate a transform matrix and construct GKS segment
GEVTM (Evaluate transformation matrix) - Constructs a GKS segment
transformation matrix starting from a given point, a shift vector, a
rotation angle, and X and Y scale factors.
CALL GEVTM(X0,Y0,DX,DY,PHI,FX,FY,SW,MOUT)
#include <ncarg/gks.h>
void geval_tran_matrix(const Gpoint *point, const Gvec *shift,
Gdouble angle, const Gvec *scale, Gcoord_switch coord_switch, Gtran_matrix
tran_matrix);
- X0
- (Real, Input) - An X coordinate value for a fixed point to be used for the
scaling and rotation parts of the output transformation. X is either in
world coordinates or normalized device coordinates depending on the
setting of the argument SW described below.
- Y0
- (Real, Input) - A Y coordinate value for a fixed point to be used for the
scaling and rotation parts of the output transformation. Y is either in
world coordinates or normalized device coordinates depending on the
setting of the argument SW described below.
- DX
- (Real, Input) - The X component of a shift vector to be used for the
scaling part of the output transformation. DX is either in world
coordinates or normalized device coordinates depending on the setting of
the argument SW described below.
- DY
- (Real, Input) - The Y component of a shift vector to be used for the
scaling part of the output transformation. DY is either in world
coordinates or normalized device coordinates depending on the setting of
the argument SW described below.
- PHI
- (Real, Input) - The rotation angle, in radians, to be used for the
rotation part of the output transformation.
- FX
- (Real, Input) - An X coordinate scale factor to be used in the scaling
part of the output transformation.
- FY
- (Real, Input) - A Y coordinate scale factor to be used in the scaling part
of the output transformation.
- SW
- (Integer, Input) - A coordinate switch to indicate whether the values for
the arguments X0, Y0, DX, and DY (described above) are in world
coordinates or normalized device coordinates. SW=0 indicates world
coordinates and SW=1 indicates normalized device coordinates.
- MOUT
- (Real, Output) - A 2x3 array that contains the GKS transformation matrix
in a form that can be used as input to other GKS functions such as
GSSGT.
If world coordinates are used, the shift vector and the fixed
point are transformed by the current normalization transformation.
The order of the transformation operations as built into the
output matrix is: scale (relative to the fixed point); rotate (relative to
the fixed point; shift.
Elements MOUT(1,3) and MOUT(2,3) are in normalized device
coordinates and the other elements of MOUT are unitless.
The following code
PI = 3.1415926
CALL GEVTM(.5,.5,.25,0.,45.*PI/180.,.5,1.5,0,TM)
would produce a transformation matrix in TM that would: scale the
X coordinates by .5, scale the Y coordinates by 1.5 (relative to the fixed
point of (.5,.5) ); rotate by 45 degrees (relative to the fixed point
(.5,.5) ); and shift by .25 in X and 0. in Y. The input values for the fixed
point and shift vector are in world coordintes.
To use GKS routines, load the NCAR GKS-0A library ncarg_gks.
Online: gactm, gclsg, gcrsg, gcsgwk, gdsg, gqopsg, gqsgus, gssgt.,
geval_tran_matrix
Hardcopy: "User's Guide for NCAR GKS-0A Graphics"
Copyright (C) 1987-2009
University Corporation for Atmospheric Research
The use of this Software is governed by a License Agreement.