Provided by: libncarg-dev_6.1.2-7_amd64 
NAME
gactm - Accumulate (GKS) transformation matrix
DESCRIPTION
GACTM (Accumulate transformation matrix) - Constructs a GKS segment transformation matrix
by starting with an existing matrix and composing it with a shift vector, a rotation
angle, and X and Y scale factors to create a new transformation matrix. The rotation and
scaling are done with respect to a user-defined fixed point.
SYNOPSIS
CALL GACTM(MINP,X0,Y0,DX,DY,PHI,FX,FY,SW,MOUT)
C-BINDING SYNOPSIS
#include <ncarg/gks.h>
void gaccum_tran_matrix(const Gtran_matrix t_matrix, const Gpoint *point, const Gvec
*shift, Gdouble angle, const Gvec *scale, Gcoord_switch coord_switch, Gtran_matrix
tran_matrix);
DESCRIPTION
MINP (Real, Input) - A 2x3 GKS transformation 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. This
matrix is constructed by composing the scale, rotate, and shift input,
described above, with the original input matrix MINP.
USAGE
If world coordinates are used, the shift vector and the fixed point are transformed by the
current normalization transformation.
The order in which the transformations are applied is: input matrix, scale, rotate, and
shift.
Elements MOUT(1,3) and MOUT(2,3) are in normalized device coordinates and the other
elements of MOUT are unitless.
GACTM can be used to construct more general transformation matrices than GEVTM. The most
common usage of GACTM is to change the order in which the operations of scale, rotate, and
shift are applied (which is fixed in GEVTM). The example below shows how to construct a
transformation matrix that shifts first and then rotates.
EXAMPLE
Assuming that the input matrix TIN is initially the identity, the following code
PI = 3.1415926
CALL GACTM(TIN,.5,.5,.25,0.,0.,1.,1.,0,TOUT)
DO 20 I=1,2
DO 30 J=1,3
TIN(I,J) = TOUT(I,J)
30 CONTINUE
20 CONTINUE
CALL GACTM(TIN,.5,.5,0.,0.,45.*PI/180.,1.,1.,0,TOUT)
would produce a transformation matrix in TOUT that would shift by (.25,0.) first, and then
rotate by 45 degrees.
ACCESS
To use GKS routines, load the NCAR GKS-0A library ncarg_gks.
SEE ALSO
Online: gevtm, gclsg, gcrsg, gcsgwk, gdsg, gqopsg, gqsgus, gssgt., gaccum_tran_matrix
Hardcopy: "User's Guide for NCAR GKS-0A Graphics"
COPYRIGHT
Copyright (C) 1987-2009
University Corporation for Atmospheric Research
The use of this Software is governed by a License Agreement.