fglMapGrid(3G) OpenGL Reference fglMapGrid(3G)NAME
fglMapGrid1d, fglMapGrid1f, fglMapGrid2d, fglMapGrid2f - define a one- or
two-dimensional mesh
FORTRAN SPECIFICATION
SUBROUTINE fglMapGrid1d( INTEGER*4 un,
REAL*4 u1,
REAL*4 u2 )
SUBROUTINE fglMapGrid1f( INTEGER*4 un,
REAL*4 u1,
REAL*4 u2 )
SUBROUTINE fglMapGrid2d( INTEGER*4 un,
REAL*4 u1,
REAL*4 u2,
INTEGER*4 vn,
REAL*4 v1,
REAL*4 v2 )
SUBROUTINE fglMapGrid2f( INTEGER*4 un,
REAL*4 u1,
REAL*4 u2,
INTEGER*4 vn,
REAL*4 v1,
REAL*4 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] (fglMapGrid2 only).
v1, v2
Specify the mappings for integer grid domain values j = 0 and j = vn
(fglMapGrid2 only).
DESCRIPTION
fglMapGrid and fglEvalMesh are used together to efficiently generate and
evaluate a series of evenly-spaced map domain values. fglEvalMesh steps
through the integer domain of a one- or two-dimensional grid, whose range
is the domain of the evaluation maps specified by fglMap1 and fglMap2.
fglMapGrid1 and fglMapGrid2 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 fglMap1 and fglMap2 for details of
how u and v coordinates are evaluated.
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fglMapGrid(3G) OpenGL Reference fglMapGrid(3G)
fglMapGrid1 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 so that
u = i(u2-u1)/un + u1
fglMapGrid2 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 fglMapGrid are used identically by fglEvalMesh
and fglEvalPoint.
ERRORS
GL_INVALID_VALUE is generated if either un or vn is not positive.
GL_INVALID_OPERATION is generated if fglMapGrid is executed between the
execution of fglBegin and the corresponding execution of fglEnd.
ASSOCIATED GETS
fglGet with argument GL_MAP1_GRID_DOMAIN
fglGet with argument GL_MAP2_GRID_DOMAIN
fglGet with argument GL_MAP1_GRID_SEGMENTS
fglGet with argument GL_MAP2_GRID_SEGMENTS
SEE ALSO
fglEvalCoord, fglEvalMesh, fglEvalPoint, fglMap1, fglMap2
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