142 lines
3.5 KiB
Plaintext
142 lines
3.5 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 mapgrid.g
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.ds Xs 53033 5 mapgrid.gl
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.TH GLMAPGRID 3G
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.SH NAME
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.B "glMapGrid1d, glMapGrid1f, glMapGrid2d, glMapGrid2f
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\- define a one- or two-dimensional mesh
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.SH C SPECIFICATION
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void \f3glMapGrid1d\fP(
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GLint \fIun\fP,
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.nf
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.ta \w'\f3void \fPglMapGrid1d( 'u
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GLdouble \fIu1\fP,
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GLdouble \fIu2\fP )
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.fi
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void \f3glMapGrid1f\fP(
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GLint \fIun\fP,
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.nf
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.ta \w'\f3void \fPglMapGrid1f( 'u
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GLfloat \fIu1\fP,
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GLfloat \fIu2\fP )
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.fi
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void \f3glMapGrid2d\fP(
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GLint \fIun\fP,
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.nf
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.ta \w'\f3void \fPglMapGrid2d( 'u
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GLdouble \fIu1\fP,
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GLdouble \fIu2\fP,
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GLint \fIvn\fP,
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GLdouble \fIv1\fP,
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GLdouble \fIv2\fP )
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.fi
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void \f3glMapGrid2f\fP(
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GLint \fIun\fP,
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.nf
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.ta \w'\f3void \fPglMapGrid2f( 'u
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GLfloat \fIu1\fP,
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GLfloat \fIu2\fP,
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GLint \fIvn\fP,
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GLfloat \fIv1\fP,
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GLfloat \fIv2\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'\f2un\fP\ \ 'u
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\f2un\fP
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Specifies the number of partitions in the grid range interval
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[\f2u1\fP, \f2u2\fP].
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Must be positive.
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.TP
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\f2u1\fP, \f2u2\fP
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Specify the mappings for integer grid domain values $i~=~0$ and $i~=~"un"$.
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.TP
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\f2vn\fP
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Specifies the number of partitions in the grid range interval
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[\f2v1\fP, \f2v2\fP]
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.br
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(\%\f3glMapGrid2\fP only).
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.TP
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\f2v1\fP, \f2v2\fP
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Specify the mappings for integer grid domain values $j~=~0$ and $j~=~"vn"$
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.br
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(\%\f3glMapGrid2\fP only).
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.SH DESCRIPTION
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\%\f3glMapGrid\fP and \%\f3glEvalMesh\fP are used together to efficiently
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generate and evaluate a series of evenly-spaced map domain values.
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\%\f3glEvalMesh\fP steps through the integer domain
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of a one- or two-dimensional grid,
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whose range is the domain of the evaluation maps specified by
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\%\f3glMap1\fP and \%\f3glMap2\fP.
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.P
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\%\f3glMapGrid1\fP and \%\f3glMapGrid2\fP specify the linear grid mappings
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between the $i$
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(or $i$ and $j$)
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integer grid coordinates,
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to the $u$
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(or $u$ and $v$)
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floating-point evaluation map coordinates.
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See \%\f3glMap1\fP and \%\f3glMap2\fP for details of how $u$ and $v$ coordinates
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are evaluated.
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.P
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\%\f3glMapGrid1\fP specifies a single linear mapping
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such that integer grid coordinate 0 maps exactly to \f2u1\fP,
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and integer grid coordinate \f2un\fP maps exactly to \f2u2\fP.
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All other integer grid coordinates $i$ are mapped so that
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.sp
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.ce
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.EQ
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u ~=~ i ("u2" - "u1") / "un" ~+~ "u1"
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.EN
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.sp
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\%\f3glMapGrid2\fP specifies two such linear mappings.
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One maps integer grid coordinate $i~=~0$ exactly to \f2u1\fP,
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and integer grid coordinate $i~=~"un"$ exactly to \f2u2\fP.
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The other maps integer grid coordinate $j~=~0$ exactly to \f2v1\fP,
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and integer grid coordinate $j~=~"vn"$ exactly to \f2v2\fP.
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Other integer grid coordinates $i$ and $j$ are mapped such that
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.P
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.ce
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.EQ
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u ~=~ i ("u2" - "u1") / "un" ~+~ "u1"
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.EN
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.P
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.ce
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.EQ
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v ~=~ j ("v2" - "v1") / "vn" ~+~ "v1"
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.EN
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.P
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The mappings specified by \%\f3glMapGrid\fP are used identically by
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\%\f3glEvalMesh\fP and \%\f3glEvalPoint\fP.
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.SH ERRORS
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\%\f3GL_INVALID_VALUE\fP is generated if either \f2un\fP or \f2vn\fP is not
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positive.
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.P
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\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glMapGrid\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 ASSOCIATED GETS
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\%\f3glGet\fP with argument \%\f3GL_MAP1_GRID_DOMAIN\fP
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.br
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\%\f3glGet\fP with argument \%\f3GL_MAP2_GRID_DOMAIN\fP
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.br
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\%\f3glGet\fP with argument \%\f3GL_MAP1_GRID_SEGMENTS\fP
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.br
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\%\f3glGet\fP with argument \%\f3GL_MAP2_GRID_SEGMENTS\fP
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.SH SEE ALSO
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\%\f3glEvalCoord(3G)\fP,
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\%\f3glEvalMesh(3G)\fP,
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\%\f3glEvalPoint(3G)\fP,
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\%\f3glMap1(3G)\fP,
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\%\f3glMap2(3G)\fP
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