glMapGrid(3G)		       OpenGL Reference			 glMapGrid(3G)



NAME
     glMapGrid1d, glMapGrid1f, glMapGrid2d, glMapGrid2f	- define a one-	or
     two-dimensional mesh


C SPECIFICATION
     void glMapGrid1d( GLint un,
		       GLdouble	u1,
		       GLdouble	u2 )
     void glMapGrid1f( GLint un,
		       GLfloat u1,
		       GLfloat u2 )
     void glMapGrid2d( GLint un,
		       GLdouble	u1,
		       GLdouble	u2,
		       GLint vn,
		       GLdouble	v1,
		       GLdouble	v2 )
     void glMapGrid2f( GLint un,
		       GLfloat u1,
		       GLfloat u2,
		       GLint vn,
		       GLfloat v1,
		       GLfloat v2 )


PARAMETERS
     un	 Specifies the number of partitions in the grid	range interval [u1,
	 u2].  Must be positive.

     u1, u2
	 Specify the mappings for integer grid domain values i=0 and i=un.

     vn	 Specifies the number of partitions in the grid	range interval [v1,
	 v2] (glMapGrid2 only).

     v1, v2
	 Specify the mappings for integer grid domain values j=0 and j=vn
	 (glMapGrid2 only).


DESCRIPTION
     glMapGrid and glEvalMesh are used in tandem to efficiently	generate and
     evaluate a	series of evenly spaced	map domain values.  glEvalMesh steps
     through the integer domain	of a one- or two-dimensional grid, whose range
     is	the domain of the evaluation maps specified by glMap1 and glMap2.

     glMapGrid1	and glMapGrid2 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 glMap1 and glMap2 for details of
     how u and v coordinates are evaluated.




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glMapGrid(3G)		       OpenGL Reference			 glMapGrid(3G)



     glMapGrid1	specifies a single linear mapping such that integer grid
     coordinate	0 maps exactly to u1, and integer grid coordinate un maps
     exactly to	u2.  All other integer grid coordinates	i are mapped such that

			       u = i(u2-u1)/un + u1

     glMapGrid2	specifies two such linear mappings.  One maps integer grid
     coordinate	i=0 exactly to u1, and integer grid coordinate i=un exactly to
     u2.  The other maps integer grid coordinate j=0 exactly to	v1, and
     integer grid coordinate j=vn exactly to v2.  Other	integer	grid
     coordinates i and j are mapped such that

			       u = i(u2-u1)/un + u1

			       v = j(v2-v1)/vn + v1

     The mappings specified by glMapGrid are used identically by glEvalMesh
     and glEvalPoint.

ERRORS
     GL_INVALID_VALUE is generated if either un	or vn is not positive.

     GL_INVALID_OPERATION is generated if glMapGrid is executed	between	the
     execution of glBegin and the corresponding	execution of glEnd.

ASSOCIATED GETS
     glGet with	argument GL_MAP1_GRID_DOMAIN
     glGet with	argument GL_MAP2_GRID_DOMAIN
     glGet with	argument GL_MAP1_GRID_SEGMENTS
     glGet with	argument GL_MAP2_GRID_SEGMENTS


SEE ALSO
     glEvalCoord, glEvalMesh, glEvalPoint, glMap1, glMap2





















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