ncl_ngritd (3) - Linux Manuals

ncl_ngritd: Given the coordinates of a point, this routine performs a rotation

NAME

NGRITD - Given the coordinates of a point, this routine performs a rotation of that point about a specified axis by a specified angle.

SYNOPSIS

CALL NGRITD (IAXS,ANGL,UCRD,VCRD,WCRD)

C-BINDING SYNOPSIS

#include <ncarg/ncargC.h>

void c_ngritd(int iaxs, float angl, float *ucrd, float *ycrd,
float *wcrd)

DESCRIPTION

IAXS

(an input expression of type INTEGER) specifies the axis about which rotation is to be done (1 for the U axis, 2 for the V axis, and 3 for the W axis).

ANGL

(an input expression of type REAL) specifies the magnitude, in degrees, of the rotation angle.

UCRD

(an input/output variable of type REAL) specifies the U coordinate of the point being rotated.

VCRD

(an input/output variable of type REAL) specifies the V coordinate of the point being rotated.

WCRD

(an input/output variable of type REAL) specifies the W coordinate of the point being rotated.

C-BINDING DESCRIPTION

The C binding argument descriptions are the same as the FORTRAN argument descriptions.

USAGE

This routine is used by NGGCOG and NGGSOG to effect the rotations that are used to generate an object of a specified shape at a specified point on the surface of the globe.

NGRITD assumes that the UVW coordinate system is right-handed. Positive values of ANGL give counter-clockwise rotations and negative values of ANGL give clockwise rotations. (When IAXS = 1, ANGL = 90 carries the positive V axis into the positive W axis; when IAXS = 2, ANGL = 90 carries the positive W axis into the positive U axis; when IAXS = 3, ANGL = 90 carries the positive U axis into the positive V axis.)

EXAMPLES

Use the ncargex command to see the following relevant example: cpex10.

ACCESS

To use NGRITD or c_ngritd, load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in that order.

MESSAGES

None.

COPYRIGHT

Copyright (C) 1987-2009
University Corporation for Atmospheric Research
The use of this Software is governed by a License Agreement.