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

## circ Subroutine

### Purpose

Outlines a circle.

### Libraries

Graphics Library

C (**libgl.a**)

FORTRAN (**libfgl.a**)

### C Syntax

**void circ(Coord ***x***, Coord ***y***, Coord** *radius***)**

**void circi(Icoord ***x***, Icoord** *y***, Icoord** *radius***)**

**void circs(Scoord ***x***, Scoord** *y***, Scoord** *radius***)**

### FORTRAN Syntax

**SUBROUTINE CIRC(***x***, ***y***, ***radius***)**
**REAL ***x***, ***y***, ***radius*

**SUBROUTINE CIRCI(***x***, ***y***, ***radius***)**
**INTEGER*4 ***x***, ***y***, ***radius*

**SUBROUTINE CIRCS(***x***, ***y***, ***radius***)**
**INTEGER*2 ***x***, ***y***, ***radius*

**Note: **For FORTRAN users, the INTEGER*2 version, the **CIRCS** subroutine, should not be called with integer constant parameters. For example, 2 is an integer constant; JJ is an integer variable. The XL FORTRAN compiler, invoked by the **xlf** command, stores all integer constants as long integers (INTEGER*4), not as short integers (INTEGER*2). Invoking the short version of this subroutine with an integer constant will result in unexpected behavior.

### Description

The **circ **subroutine draws an unfilled circle in the *x*-*y *plane (*z =* 0). The system draws the circle using the current line attributes:
color,
linestyle,
linewidth,
repeat factor, and
writemask.

To create a circle that does not lie in the *x*-*y *plane, draw the circle in the *x*-*y* plane, then rotate or translate the circle. Circles rotated outside the 2-D *x*-*y *plane appear as ellipses.

All of the routines listed in the syntax are functionally the same. They differ only in the type declarations for the coordinates.

### Parameters

*x* |
Specifies the *x* coordinate of the center of the circle specified in modeling coordinates. |

*y* |
Specifies the *y* coordinate of the center of the circle specified in modeling coordinates. |

*radius* |
Specifies the length of the radius of the circle. |

### Example

The example C language program **boxcirc.c** uses the **circi** subroutine to draw a red circle.

### 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

Drawing a circular arc with the **arc** subroutine.

Drawing a filled circular arc with the **arcf** subroutine.

Drawing a filled circle with the **circf** subroutine.

Drawing a curve with the **crv** subroutine.

AIX Graphics Library Overview, Setting Drawing Attributes, and Drawing Rectangles, Circles, Arcs, and Polygons.

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