glGetMap
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## Name

glGetMapdv, glGetMapfv, glGetMapiv — 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`);`

## Python Specification

``glGetMapdv`` | `(` | ``target`, `query`) → `v``
``glGetMapfv`` | `(` | ``target`, `query`) → `v``
``glGetMapiv`` | `(` | ``target`, `query`) → `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

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