NAME

spps_converters - A set of functions, each of which transforms a coordinate from one of the NCAR Graphics coordinate systems to another. The complete list of functions is as follows: CFUX, CFUY, CMFX, CMFY, CMUX, CMUY, CPFX, CPFY, CPUX, CPUY, CUFX, CUFY, KFMX, KFMY, KFPX, KFPY, KMPX, KMPY, KPMX, KPMY, KUMX, KUMY, KUPX, and KUPY.

STATUS

Plotter Address Units (PAUs) and Metacode Units (MUs) are no longer used in NCAR Graphics; thus, all functions with either an M or a P as the second or third letter of the function name are considered obsolete.

The current recognized coordinate systems are GKS world coordinates, GKS normalized device coordinates, NCAR Graphics fractional coordinates, and NCAR Graphics user coordinates. See the NCAR Graphics document "NCAR Graphics Fundamentals, UNIX Version" for descriptions of these coordinate systems.

The following definitions of the PAU coordinate system and the MU coordinate system are provided for the purpose of interpreting and converting codes which use PAUs or MUs:

The plotter coordinates of a point are integers IPX and IPY, where IPX is between 1 and 2**MX and IPY is between 1 and 2**MY. MX and MY are internal parameters of SPPS; each has a default value of 10. Values of MX and MY can be set by calling the routines SETI or SETUSV and retrieved by calling the routines GETSI or GETUSV.

The metacode coordinates of a point are integers IMX and IMY between 0 and 32767 inclusive. The area addressed is a square in a "metacode space" that is usually mapped into a square subset of the addressable area of the plotting device. Metacode coordinates were used in calls to the routine PLOTIT and are returned in calls to FL2INT.

SYNOPSIS

Current:
X = CFUX (RX), Y = CFUY(RY)
X = CUFX (RX), Y = CUFY(RY)
Obsolete:
X = CMUX (IX), Y = CMUY(IY)
X = CPUX (IX), Y = CPUY(IY)
X = CMFX (IX), Y = CMFY(IY)
X = CPFX (IX), Y = CPFY(IY)
I = KFMX (RX), J = KFMY(RY)
I = KUMX (RX), J = KUMY(RY)
I = KFPX (RX), J = KFPY(RY)
I = KUPX (RX), J = KUPY(RY)
I = KPMX (IX), J = KPMY(IY)
I = KMPX (IX), J = KMPY(IY)

C-BINDING SYNOPSIS

#include <ncarg/ncargC.h>

float c_cfux (float rx)

float c_cfuy (float ry)

float c_cufx (float rx)

float c_cufy (float ry)

DESCRIPTION

RX

(an input expression of type REAL) is an X coordinate in the coordinate system specified by the second letter of the function name. In a reference to CFUX, RX is a fractional X coordinate; in a reference to CUFX, RX is a user X coordinate.

RY

(an input expression of type REAL) is a Y coordinate in the coordinate system specified by the second letter of the function name. In a reference to CFUY, RY is a fractional Y coordinate; in a reference to CUFY, RY is a user Y coordinate.

IX and IY occur as arguments only in references to some of the obsolete functions; they represent input expressions of type INTEGER, specifying the X and Y coordinates of a point in either PAUs or MUs (depending on the second letter of the function name).

The first letter of the function name is a C if the result is of type REAL and a K if the result is of type INTEGER (the latter only happens for some of the obsolete ones). This conforms to the usual FORTRAN convention for implicit typing.

The second letter of the function name specifies the coordinate system of the argument.

The third letter of the function name specifies the coordinate system of the functional result. In references to CFUX and CFUY, the result is in the user system; in references to CUFX and CUFY, the result is in the fractional system.

The fourth letter of the function name is an X or a Y, depending on whether an X or a Y coordinate is being converted.

C-BINDING DESCRIPTION

The C-binding argument description is the same as the FORTRAN argument description.

EXAMPLES

Use the ncargex command to see the following relevant examples which use coordinate converters: mpex10, cbex10, sfex02, epltch.

The command "ncargex -n mpex10" will load the driver mpex10.f into your current working directory where you can examine the file using a local editor, or the UNIX more command.

ACCESS

There were 24 conversion functions in the original set. These functions (12 for the X coordinate of a point, and 12 for the Y coordinate), allowed one to convert between any combination of PAUs, MUs, fractional coordinates, and user coordinates. PAUs and MUs are now obsolete; thus, only four of the conversion functions are still pertinent: CFUX and CFUY allow one to convert the X and Y coordinates of a point from the fractional system to the user system, while CUFX and CUFY do the opposite.

To use any of the conversion routines, load the load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in that order.

COPYRIGHT

Copyright (C) 1987-2009
University Corporation for Atmospheric Research

The use of this Software is governed by a License Agreement.