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doc/gl-docs/GL/gl/mapgrid.3gl

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+'\" te
+'\"! tbl|eqn | mmdoc
+'\"macro stdmacro
+.ds Vn Version 1.2
+.ds Dt 24 September 1999
+.ds Re Release 1.2.1
+.ds Dp Jan 14 18:30
+.ds Dm 01 mapgrid.g
+.ds Xs 53033 5 mapgrid.gl
+.TH GLMAPGRID 3G
+.SH NAME
+.B "glMapGrid1d, glMapGrid1f, glMapGrid2d, glMapGrid2f
+\- define a one- or two-dimensional mesh
+
+.SH C SPECIFICATION
+void \f3glMapGrid1d\fP(
+GLint \fIun\fP,
+.nf
+.ta \w'\f3void \fPglMapGrid1d( 'u
+	GLdouble \fIu1\fP,
+	GLdouble \fIu2\fP )
+.fi
+void \f3glMapGrid1f\fP(
+GLint \fIun\fP,
+.nf
+.ta \w'\f3void \fPglMapGrid1f( 'u
+	GLfloat \fIu1\fP,
+	GLfloat \fIu2\fP )
+.fi
+void \f3glMapGrid2d\fP(
+GLint \fIun\fP,
+.nf
+.ta \w'\f3void \fPglMapGrid2d( 'u
+	GLdouble \fIu1\fP,
+	GLdouble \fIu2\fP,
+	GLint \fIvn\fP,
+	GLdouble \fIv1\fP,
+	GLdouble \fIv2\fP )
+.fi
+void \f3glMapGrid2f\fP(
+GLint \fIun\fP,
+.nf
+.ta \w'\f3void \fPglMapGrid2f( 'u
+	GLfloat \fIu1\fP,
+	GLfloat \fIu2\fP,
+	GLint \fIvn\fP,
+	GLfloat \fIv1\fP,
+	GLfloat \fIv2\fP )
+.fi
+
+.EQ
+delim $$
+.EN
+.SH PARAMETERS
+.TP \w'\f2un\fP\ \ 'u 
+\f2un\fP
+Specifies the number of partitions in the grid range interval
+[\f2u1\fP, \f2u2\fP].
+Must be positive.
+.TP
+\f2u1\fP, \f2u2\fP
+Specify the mappings for integer grid domain values $i~=~0$ and $i~=~"un"$.
+.TP
+\f2vn\fP
+Specifies the number of partitions in the grid range interval
+[\f2v1\fP, \f2v2\fP]
+.br
+(\%\f3glMapGrid2\fP only).
+.TP
+\f2v1\fP, \f2v2\fP
+Specify the mappings for integer grid domain values $j~=~0$ and $j~=~"vn"$
+.br
+(\%\f3glMapGrid2\fP only).
+.SH DESCRIPTION
+\%\f3glMapGrid\fP and \%\f3glEvalMesh\fP are used together to efficiently
+generate and evaluate a series of evenly-spaced map domain values.
+\%\f3glEvalMesh\fP steps through the integer domain
+of a one- or two-dimensional grid,
+whose range is the domain of the evaluation maps specified by
+\%\f3glMap1\fP and \%\f3glMap2\fP.
+.P
+\%\f3glMapGrid1\fP and \%\f3glMapGrid2\fP specify the linear grid mappings
+between the $i$
+(or $i$ and $j$)
+integer grid coordinates,
+to the $u$
+(or $u$ and $v$)
+floating-point evaluation map coordinates.
+See \%\f3glMap1\fP and \%\f3glMap2\fP for details of how $u$ and $v$ coordinates
+are evaluated.
+.P
+\%\f3glMapGrid1\fP specifies a single linear mapping
+such that integer grid coordinate 0 maps exactly to \f2u1\fP,
+and integer grid coordinate \f2un\fP maps exactly to \f2u2\fP.
+All other integer grid coordinates $i$ are mapped so that
+.sp
+.ce
+.EQ
+u ~=~ i ("u2" - "u1") / "un" ~+~ "u1"
+.EN
+.sp
+\%\f3glMapGrid2\fP specifies two such linear mappings.
+One maps integer grid coordinate $i~=~0$ exactly to \f2u1\fP,
+and integer grid coordinate $i~=~"un"$ exactly to \f2u2\fP.
+The other maps integer grid coordinate $j~=~0$ exactly to \f2v1\fP,
+and integer grid coordinate $j~=~"vn"$ exactly to \f2v2\fP.
+Other integer grid coordinates $i$ and $j$ are mapped such that
+.P
+.ce
+.EQ
+u ~=~ i ("u2" - "u1") / "un" ~+~ "u1"
+.EN
+.P
+.ce
+.EQ
+v ~=~ j ("v2" - "v1") / "vn" ~+~ "v1"
+.EN
+.P
+The mappings specified by \%\f3glMapGrid\fP are used identically by
+\%\f3glEvalMesh\fP and \%\f3glEvalPoint\fP.
+.SH ERRORS
+\%\f3GL_INVALID_VALUE\fP is generated if either \f2un\fP or \f2vn\fP is not
+positive.
+.P
+\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glMapGrid\fP
+is executed between the execution of \%\f3glBegin\fP
+and the corresponding execution of \%\f3glEnd\fP.
+.SH ASSOCIATED GETS
+\%\f3glGet\fP with argument \%\f3GL_MAP1_GRID_DOMAIN\fP
+.br
+\%\f3glGet\fP with argument \%\f3GL_MAP2_GRID_DOMAIN\fP
+.br
+\%\f3glGet\fP with argument \%\f3GL_MAP1_GRID_SEGMENTS\fP
+.br
+\%\f3glGet\fP with argument \%\f3GL_MAP2_GRID_SEGMENTS\fP
+.SH SEE ALSO
+\%\f3glEvalCoord(3G)\fP,
+\%\f3glEvalMesh(3G)\fP,
+\%\f3glEvalPoint(3G)\fP,
+\%\f3glMap1(3G)\fP,
+\%\f3glMap2(3G)\fP