Provided by: libncarg-dev_6.6.2.dfsg.1-1_amd64 
NAME
geval_tran_matrix - Connstruct GKS segment by evaluating a transform matrix
DESCRIPTION
geval_tran_matrix (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.
SYNOPSIS
#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);
DESCRIPTION
point.x (Gfloat, Input) - An X coordinate value for a fixed point to be used for the
scaling and rotation parts of the output transformation. point.x is either in
world coordinates or normalized device coordinates depending on the setting of
the argument coord_switch described below.
point.y (Gfloat, Input) - A Y coordinate value for a fixed point to be used for the
scaling and rotation parts of the output transformation. point.y is either in
world coordinates or normalized device coordinates depending on the setting of
the argument coord_switch described below.
shift.delta_x
(Gfloat, Input) - The X component of a shift vector to be used for the scaling
part of the output transformation. shift.delta_x is either in world
coordinates or normalized device coordinates depending on the setting of the
argument coord_switch described below.
shift.delta_y
(Gfloat, Input) - The Y component of a shift vector to be used for the scaling
part of the output transformation. shift.delta_y is either in world
coordinates or normalized device coordinates depending on the setting of the
argument coord_switch described below.
angle (Input) - The rotation angle, in radians, to be used for the rotation part of
the output transformation.
scale.delta_x
(Gfloat Input) - An X coordinate scale factor to be used in the scaling part
of the output transformation.
scale.delta_y
(Gfloat Input) - A Y coordinate scale factor to be used in the scaling part of
the output transformation.
coord_switch
(Input) - A coordinate switch to indicate whether the values for the arguments
shift and scale (described above) are in world coordinates or normalized
device coordinates. Possible values include:
GCOORD_WC
World coordinates
GCOORD_NDC
Normalized device coordinates
tran_matrix (Gfloat, 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 gset_seg_tran.
USAGE
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 tran_matrix[0][2] and tran_matrix[1][2] are in normalized device coordinates and
the other elements of tran_matrix are unitless.
EXAMPLE
The following code
pi = 3.1415926;
point.x = point.y = 0.5;
shift.delta_x = 0.25;
shift.delta_y = 0.;
scale.delta_x = 0.5;
scale.delta_y = 1.5;
geval_tran_matrix(&point,&shift,45.*pi/180.,&scale,GCOORD_WC,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.
ACCESS
To use the GKS C-binding routines, load the ncarg_gks and ncarg_c libraries.
SEE ALSO
Online: gaccum_tran_matrix(3NCARG), gclose_seg(3NCARG), gcreate_seg(3NCARG),
gcopy_seg_ws(3NCARG), gdel_seg(3NCARG), ginq_name_open_seg(3NCARG),
ginq_set_seg_names(3NCARG), gset_seg_tran(3NCARG), gks(3NCARG), ncarg_gks_cbind(3NCARG)
Hardcopy: User's Guide for NCAR GKS-0A Graphics; NCAR Graphics Fundamentals, UNIX Version
COPYRIGHT
Copyright (C) 1987-2009
University Corporation for Atmospheric Research
The use of this Software is governed by a License Agreement.