glGetMap Subroutine

OpenGL 1.1 for AIX: Reference Manual

glGetMap Subroutine

Purpose

Returns evaluator parameters.

Library

OpenGL C bindings library: libGL.a

C Syntax

void glGetMapdv(GLenum Target,
                GLenum Query, 
                GLdouble *v)

void glGetMapfv(GLenum Target,
               GLenum Query,
               GLfloat *v)

void glGetMapiv(GLenum Target,
               GLenum Query,
               GLint *v)

Parameters

Target	Specifies the symbolic name of a map. Accepted values are GL_MAP1_COLOR_4, GL_MAP1_INDEX, GL_MAP1_NORMAL, GL_MAP1_TEXTURE_COORD_1, GL_MAP1_TEXTURE_COORD_2, GL_MAP1_TEXTURE_COORD_3, GL_MAP1_TEXTURE_COORD_4, GL_MAP1_VERTEX_3, GL_MAP1_VERTEX_4, GL_MAP2_COLOR_4, GL_MAP2_INDEX, GL_MAP2_NORMAL, GL_MAP2_TEXTURE_COORD_1, GL_MAP2_TEXTURE_COORD_2, GL_MAP2_TEXTURE_COORD_3, GL_MAP2_TEXTURE_COORD_4, GL_MAP2_VERTEX_3, and GL_MAP2_VERTEX_4.
Query	Specifies which parameter to return. Symbolic names GL_COEFF, GL_ORDER, and GL_DOMAIN are accepted.
v	Returns the requested data.

Description

The glMap1 and glMap2 subroutines define evaluators. The glGetMap subroutine returns evaluator parameters. Target chooses a map, Query selects a specific parameter, and v points to storage where the values are returned. (See the glMap1 and glMap2 subroutines for a description of the acceptable values for the Target parameter.)

Query can assume the following values:

GL_COEFF	v returns the control points for the evaluator function. One-dimensional (1D) evaluators return order control points, and two-dimensional (2D) evaluators return uorder x vorder control points. Each control point consists of 1, 2, 3, or 4 integer, single-precision floating-point, or double-precision floating-point values, depending on the type of the evaluator. Two-dimensional control points are returned in row major order, incrementing the uorder index quickly, and the vorder index after each row. Integer values, when requested, are computed by rounding the internal floating-point values to the nearest integer values.
GL_ORDER	v returns the order of the evaluator function. One-dimensional evaluators return a single value, order. Two-dimensional evaluators return two values, uorder and vorder.
GL_DOMAIN	v returns the linear u and v mapping parameters. One-dimensional evaluators return two values, u1 and u2, as specified by glMap1. Two-dimensional evaluators return four values, u1, u2, v1, and v2, as specified by glMap2. Integer values, when requested, are computed by rounding the internal floating-point values to the nearest integer values.

Notes

If an error is generated, no change is made to the contents of v.

Errors

GL_INVALID_ENUM	Either Target or Query is not an accepted value.
GL_INVALID_OPERATION	The glGetMap subroutine is called between a call to glBegin and the corresponding call to glEnd.

Files

/usr/include/GL/gl.h

Contains C language constants, variable type definitions, and ANSI function prototypes for OpenGL.

Related Information

The glBegin or glEnd subroutine, glEvalCoord subroutine, glMap1 subroutine, glMap2 subroutine.

OpenGL Overview.