[ Previous | Next | Contents | Glossary | Home | Search ]
GL3.2 for AIX: Graphics Library (GL) Technical Reference

concave Subroutine

Purpose

Forces the system to draw accurate concave polygons.

Libraries

Graphics Library

C (libgl.a)

FORTRAN (libfgl.a)

C Syntax

void concave(Int32 bool)

FORTRAN Syntax

SUBROUTINE CONCAV(bool)
LOGICAL bool

Description

The concave subroutine forces the system to draw accurate concave polygons. When the bool parameter is True (1), the system draws accurate concave polygons. When the value of the bool parameter is False (0) (the default), the results of drawing a concave polygon are unpredictable.

The system draws polygons significantly faster if checking for concavity is turned off. Therefore, unless you specifically want to draw concave polygons, you should generally operate with the bool parameter set to False.

Parameter

bool Specifies a value for the state of concavity. The settings for the bool parameter are:
True System draws accurate concave and convex polygons.
False System draws only accurate convex polygons. This is the default.

Implementation Specifics

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

On the POWERgraphics GXT1000, the value of the concave flag is ignored when drawing into the overlay planes.

If the concave flag has been set to TRUE, then the GXT1000 limits the number of vertices that can appear between a bgnline and endline pair to 255 vertices. Otherwise, an unlimited number of vertices can be specified.

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 vertex-based polygon with the bgnpolygon subroutine.

Specifying the next point in a polygon with the pdr subroutine.

Specifying the starting point for a polygon with the pmv subroutine.

Drawing a filled polygon with the polf subroutine.

Drawing a polygon with the poly subroutine.

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


[ Previous | Next | Contents | Glossary | Home | Search ]