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

curveit Subroutine


Draws a curve segment by iterating the forward difference matrix.


Graphics Library

C (libgl.a)

FORTRAN (libfgl.a)

C Syntax

void curveit(Int16 count)


INTEGER*4 count
Note: For FORTRAN users, this subroutine accepts long integer parameters (INTEGER*4) when invoked from a FORTRAN program, although it accepts short integers when invoked from a C program. The C and FORTRAN syntax shown here reflect this difference.


The curveit subroutine repeats the forward difference algorithm with the current matrix (the one on top of the matrix stack) for the number of times assigned by the count parameter. Each iteration draws one of the line segments that approximate the curve. The curveit subroutine accesses low-level hardware capabilities for curve drawing.


count Specifies the number of times to repeat the current matrix.


The example C language program curve3.c uses the curveit subroutine to draw a Bezier curve segment after building the correct transformation matrix.

Implementation Specifics

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


/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 cubic spline curve with the crv subroutine.

AIX Graphics Library Overview, Drawing NURBS Curves and Surfaces, and Drawing Wire Frame Curves and Surface Patches.

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