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

curvebasis Subroutine


Sets the current cubic spline curve basis matrix.


Graphics Library

C (libgl.a)

FORTRAN (libfgl.a)

C Syntax

void curvebasis(Int32 basis_id)


INTEGER*4 basis_id


The curvebasis subroutine sets a basis matrix as defined by the defbasis subroutine as the current basis matrix to draw curve segments. The basis matrix determines how the system uses the control points when drawing a curve.

Depending on the basis matrix, the system draws Bezier curves, Cardinal spline curves, B-spline curves, and others. The system does not restrict you to a limited set of basis matrices. You can define basis matrices to match whatever constraints you want to place on the curve.


basis_id Specifies the basis identifier of the basis matrix to use when drawing a curve.


The example C language program curve1.c uses the curvebasis subroutine to select each of three previously defined basis matrices, then draws a curve using each basis 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.

Drawing a series of curve segments with the crvn subroutine.

Setting the number of line segments that compose a cubic spline curve with the curveprecision subroutine.

Defining a cubic spline basis matrix with the defbasis subroutine.

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

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