135 lines
3.6 KiB
Plaintext
135 lines
3.6 KiB
Plaintext
'\" te
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'\"! tbl|eqn | mmdoc
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'\"macro stdmacro
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.ds Vn Version 1.2
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.ds Dt 24 September 1999
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.ds Re Release 1.2.1
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.ds Dp Jan 14 18:30
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.ds Dm 01 getmap.gl
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.ds Xs 19970 5 getmap.gl
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.TH GLGETMAP 3G
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.SH NAME
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.B "glGetMapdv, glGetMapfv, glGetMapiv
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\- return evaluator parameters
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.SH C SPECIFICATION
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void \f3glGetMapdv\fP(
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GLenum \fItarget\fP,
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.nf
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.ta \w'\f3void \fPglGetMapdv( 'u
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GLenum \fIquery\fP,
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GLdouble \fI*v\fP )
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.fi
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void \f3glGetMapfv\fP(
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GLenum \fItarget\fP,
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.nf
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.ta \w'\f3void \fPglGetMapfv( 'u
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GLenum \fIquery\fP,
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GLfloat \fI*v\fP )
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.fi
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void \f3glGetMapiv\fP(
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GLenum \fItarget\fP,
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.nf
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.ta \w'\f3void \fPglGetMapiv( 'u
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GLenum \fIquery\fP,
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GLint \fI*v\fP )
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.fi
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.EQ
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delim $$
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.EN
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.SH PARAMETERS
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.TP \w'\f2target\fP\ \ 'u
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\f2target\fP
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Specifies the symbolic name of a map.
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Accepted values are
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\%\f3GL_MAP1_COLOR_4\fP,
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\%\f3GL_MAP1_INDEX\fP,
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\%\f3GL_MAP1_NORMAL\fP,
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\%\f3GL_MAP1_TEXTURE_COORD_1\fP,
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\%\f3GL_MAP1_TEXTURE_COORD_2\fP,
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\%\f3GL_MAP1_TEXTURE_COORD_3\fP,
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\%\f3GL_MAP1_TEXTURE_COORD_4\fP,
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\%\f3GL_MAP1_VERTEX_3\fP,
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\%\f3GL_MAP1_VERTEX_4\fP,
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\%\f3GL_MAP2_COLOR_4\fP,
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\%\f3GL_MAP2_INDEX\fP,
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\%\f3GL_MAP2_NORMAL\fP,
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\%\f3GL_MAP2_TEXTURE_COORD_1\fP,
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\%\f3GL_MAP2_TEXTURE_COORD_2\fP,
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\%\f3GL_MAP2_TEXTURE_COORD_3\fP,
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\%\f3GL_MAP2_TEXTURE_COORD_4\fP,
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\%\f3GL_MAP2_VERTEX_3\fP, and
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\%\f3GL_MAP2_VERTEX_4\fP.
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.TP
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\f2query\fP
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Specifies which parameter to return.
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Symbolic names
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\%\f3GL_COEFF\fP,
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\%\f3GL_ORDER\fP, and
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\%\f3GL_DOMAIN\fP are accepted.
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.TP
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\f2v\fP
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Returns the requested data.
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.SH DESCRIPTION
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\%\f3glMap1\fP and \%\f3glMap2\fP define evaluators.
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\%\f3glGetMap\fP returns evaluator parameters.
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\f2target\fP chooses a map,
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\f2query\fP selects a specific parameter,
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and \f2v\fP points to storage where the values will be returned.
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.P
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The acceptable values for the \f2target\fP parameter are described
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in the \%\f3glMap1\fP and \%\f3glMap2\fP reference pages.
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.P
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\f2query\fP can assume the following values:
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.TP 15
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\%\f3GL_COEFF\fP
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\f2v\fP returns the control points for the evaluator function.
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One-dimensional evaluators return $order$ control points,
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and two-dimensional evaluators return $uorder ~times~ vorder$ control points.
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Each control point consists of one, two, three, or four integer,
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single-precision floating-point,
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or double-precision floating-point values,
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depending on the type of the evaluator.
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The GL returns two-dimensional control points in row-major order,
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incrementing the $uorder$ index quickly
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and the $vorder$ index after each row.
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Integer values,
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when requested,
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are computed by rounding the internal floating-point values to the
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nearest integer values.
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.TP
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\%\f3GL_ORDER\fP
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\f2v\fP returns the order of the evaluator function.
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One-dimensional evaluators return a single value,
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$order$. The initial value is 1.
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Two-dimensional evaluators return two values,
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$uorder$ and $vorder$. The initial value is 1,1.
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.TP
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\%\f3GL_DOMAIN\fP
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\f2v\fP returns the linear $u$ and $v$ mapping parameters.
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One-dimensional evaluators return two values,
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$u1$ and $u2$,
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as specified by \%\f3glMap1\fP.
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Two-dimensional evaluators return four values
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($u1$, $u2$, $v1$, and $v2$)
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as specified by \%\f3glMap2\fP.
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Integer values,
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when requested,
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are computed by rounding the internal floating-point values to the
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nearest integer values.
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.SH NOTES
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If an error is generated,
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no change is made to the contents of \f2v\fP.
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.SH ERRORS
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\%\f3GL_INVALID_ENUM\fP is generated if either \f2target\fP or \f2query\fP is not
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an accepted value.
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.P
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\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glGetMap\fP
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is executed between the execution of \%\f3glBegin\fP
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and the corresponding execution of \%\f3glEnd\fP.
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.SH SEE ALSO
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\%\f3glEvalCoord(3G)\fP,
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\%\f3glMap1(3G)\fP,
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\%\f3glMap2(3G)\fP
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