GLGETMAP


HOME

GLGETMAP

NAME
C SPECIFICATION
PARAMETERS
DESCRIPTION
NOTES
ERRORS
SEE ALSO

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 )

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 $uorder ~times~ vorder$ 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(3G), glMap1(3G), glMap2(3G)






Opportunity


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.





Free Software


Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.


Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.





Free Books


The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.


Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.





Education


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.


Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.