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

## defbasis Subroutine

### Purpose

Defines a cubic spline basis matrix.

### Libraries

Graphics Library

C (**libgl.a**)

FORTRAN (**libfgl.a**)

### C Syntax

**void defbasis(Int32 ***id***, Matrix ***mat***)**

### FORTRAN Syntax

**SUBROUTINE DEFBAS(***id***,*** mat***)**
**INTEGER*4 ***id*
**REAL ***mat***(4,4)**

### Description

The **defbasis** subroutine assigns a basis matrix identifier for use by subroutines that generate curves and patches. Use the basis matrix identifier in subsequent calls to the **curvebasis** and **patchbasis** subroutines.

**Note: **This subroutine cannot be used to add to a
display list.

### Parameters

*id* |
Specifies the basis identifier to assign to the matrix. |

*mat* |
Specifies the matrix to which to assign the basis identifier. |

### Example

The example C language program **curve1.c** uses the **defbasis** subroutine to define three basis matrices for drawing curves.

### 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 cubic spline curve with the **crv** subroutine.

Drawing a series of curve segments with the **crvn** subroutine.

Setting the current cubic spline curve basis matrix with the **curvebasis** subroutine.

Setting the number of line segments that draw a curve segment with the **curveprecision** subroutine.

Drawing surface patches with the **patch** subroutine.

Setting the current spline surface basis matrices with the **patchbasis** subroutine.

Setting the number of curves used to represent a patch with the **patchcurves** subroutine.

Setting the precision at which curves are drawn with the **patchprecision** subroutine.

Drawing a rational curve with the **rcrv** subroutine.

Drawing a series of rational curve segments with the **rcrvn** subroutine.

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

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