glGetMapfv function

Article
03/09/2021

The glGetMapdv, glGetMapfv, and glGetMapiv functions return evaluator parameters.

Syntax

void WINAPI glGetMapfv(
   GLenum  target,
   GLenum  query,
   GLfloat *v
);

Parameters

target

The symbolic name of a map. The following are accepted values: 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. The following symbolic names are accepted.

Value	Meaning
GL_COEFF	The v parameter returns the control points for the evaluator function. One-dimensional evaluators return order control points, and two-dimensional evaluators return uorder x 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. 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	The v parameter 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	The v parameter returns the linear u and v mapping parameters. One-dimensional evaluators return two values, u 1 and u 2, 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.

v

Returns the requested data.

Return value

This function does not return a value.

Error codes

The following error codes can be retrieved by the glGetError function.

Name	Meaning
GL_INVALID_ENUM	target or query was not an accepted value.
GL_INVALID_OPERATION	The function was called between a call to glBegin and the corresponding call to glEnd.

Remarks

The glGetMap function returns evaluator parameters. (The glMap1 and glMap2 functions define evaluators.) The target parameter specifies 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 glMap1 and glMap2.

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

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Header	Gl.h
Library	Opengl32.lib
DLL	Opengl32.dll

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