glMapGrid1d,
glMapGrid1f, glMapGrid2d, glMapGrid2f
[New
- Windows 95, OEM Service Release 2]
These
functions define a one- or two-dimensional mesh.
void glMapGrid1d(
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GLint un, |
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GLdouble u1, |
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GLdouble u2 |
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); |
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void glMapGrid1f(
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GLint un, |
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GLfloat u1, |
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GLfloat u2 |
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); |
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void glMapGrid2d(
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GLint un, |
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GLdouble u1, |
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GLdouble u2, |
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GLint vn, |
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GLdouble v1, |
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GLdouble v2 |
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); |
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void glMapGrid2f(
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GLint un, |
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GLfloat u1, |
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GLfloat u2, |
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GLint vn, |
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GLfloat v1, |
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GLfloat v2 |
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); |
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Parameters
un
The number of
partitions in the grid range interval [u1, u2]. Must be positive.
u1,
u2
The mappings
for integer grid domain values i = 0 and i = un.
vn
The number of
partitions in the grid range interval [v1, v2] (glMapGrid2
only).
v1,
v2
The mappings
for integer grid domain values j = 0 and j = vn (glMapGrid2
only).
Remarks
The glMapGrid
and glEvalMesh
functions are used in tandem to efficiently generate and evaluate a series of
evenly spaced map domain values. The glEvalMesh function 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.
The glMapGrid1
and glMapGrid2 functions 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.
The glMapGrid1
function 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
The
glMapGrid2 function 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.
The following
functions retrieve information related to glMapGrid:
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
Error Codes
The following
are the error codes generated and their conditions.
|
Error
Code |
Condition |
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GL_INVALID_VALUE
|
Either un
or vn was not positive. |
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GL_INVALID_OPERATION
|
glMapGrid was called between a call to glBegin and the
corresponding call to glEnd. |
See Also