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GL3.2 for AIX: Graphics Library (GL) Technical Reference

## polarview Subroutine

### Purpose

Defines the viewer's position in polar coordinates.

### Libraries

Graphics Library

C (libgl.a)

FORTRAN (libfgl.a)

### C Syntax

```void polarview
(Coord distance,
Angle azimuth,
Angle incidence,
Angle twist)```

### FORTRAN Syntax

```VOID POLARV(distance, azimuth, incidence, twist)
REAL distance
INTEGER*4 azimuth, incidence, twist```

### Description

The polarview subroutine defines the viewer's position in polar coordinates. Normally, the polarview subroutine is used to set up the mapping from world coordinates to eye coordinates (equivalently, to define the location of the viewer's eye in world coordinates).

If the polarview subroutine is the first transformation subroutine called after projection matrix is set up and the matrix stack is initialized, it sets up such a mapping. The eye is located a distance, given in the distance parameter, from the world space origin. The line of sight extends from the eye through the world space origin (that is, the viewer is looking squarely upon the origin). The incidence and azimuth are measured with respect to the world coordinate system.

The polarview subroutine can also be used as a modeling transformation. Whether it behaves as a viewing transformation or a modeling transformation depends entirely on the order in which it is called with respect to the drawing subroutines.

### Parameters

 distance Specifies the distance from the eye to the world space origin. azimuth Specifies the azimuthal angle in the x-y plane, measured clockwise from the positive y axis. The angle must be specified as an integer, in tenths of a degree. incidence Specifies the angle of incidence in the y-z plane, measured from the z axis. The incidence angle is the angle of the line from origin to eye with respect to the z axis (the angle away from direct vertical, if you think of standing on the x-y plane. The angle must be specified as an integer, in tenths of a degree. twist Specifies the amount that the viewpoint is to be rotated around the line of sight using the right-hand rule. The angle must be specified as an integer, in tenths of a degree.

### Implementation Specifics

This subroutine is part of GL in the AIXwindows Environment/6000 Version 1, Release 2 with AIXwindows/3D Feature.

### Files

 /usr/include/gl/gl.h Contains C language constant and variable type definitions for GL. /usr/include/gl/fgl.h Contains FORTRAN constant and variable type definitions for GL.

### Related Information

Defining a viewing transformation with the lookat subroutine.

AIX Graphics Library Overview and Working with Coordinate Systems.

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