1991-2006 Silicon Graphics, Inc.
glGetMap 3G
glGetMap return evaluator parameters

## C Specification

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

glMap1 and glMap2 define evaluators. `glGetMap` returns evaluator parameters. target chooses a map, query selects a specific parameter, and v points to storage where the values will be returned.

The acceptable values for the target parameter are described in the glMap1 and glMap2 reference pages.

query can assume the following values:

`GL_COEFF`

  v returns the control points for the evaluator function. One-dimensional evaluators return order control points, and two-dimensional evaluators return uorder × vorder control points. Each control point consists of one, two, three, or four integer, single-precision floating-point, or double-precision floating-point values, depending on the type of the evaluator. The GL returns two-dimensional control points 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. The initial value is 1. Two-dimensional evaluators return two values, uorder and vorder. The initial value is 1,1.

`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` is generated if either target or query is not an accepted value.

`GL_INVALID_OPERATION` is generated if `glGetMap` is executed between the execution of glBegin and the corresponding execution of glEnd.

## See Also

glEvalCoord, glMap1, glMap2

## Copyright

Copyright 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.