glEvalPoint1 function
The glEvalPoint1 and glEvalPoint2 functions generate and evaluate a single point in a mesh.
Syntax
void glEvalPoint1(
GLint i
);
Parameters
-
i
-
The integer value for grid domain variable i.
Return value
This function does not return a value.
Remarks
The glMapGrid and glEvalMesh functions are used in tandem to efficiently generate and evaluate a series of evenly spaced map domain values. You can use glEvalPoint to evaluate a single grid point in the same gridspace that is traversed by glEvalMesh. Calling glEvalPoint1 is equivalent to calling
glEvalCoord1 (i ?u +u1 );
where
?u = (u2 u1 )/n
and n, u1 , and u2 are the arguments to the most recent glMapGrid1 function. The one absolute numeric requirement is that if i = n, then the value computed from (i ?u + u1 ) is exactly u2 .
In the two-dimensional case, glEvalPoint2, let
?u = (u2 u1 )/n
?v = (v2 v1 )/m
where n, u1 , u2 , m, v1 , and v2 are the arguments to the most recent glMapGrid2 function. Then the glEvalPoint2 function is equivalent to calling
glEvalCoord2 (i ?u + u1 , j ?v + v1 );
The only absolute numeric requirements are that if i=n, then the value computed from (i ?u + u1 ) is exactly u2 , and if j = m, then the value computed from (j ?v + v1 ) is exactly v2 .
The following functions retrieve information relating to glEvalPoint1 and glEvalPoint2:
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
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client |
Windows 2000 Professional [desktop apps only] |
| Minimum supported server |
Windows 2000 Server [desktop apps only] |
| Header |
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| Library |
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| DLL |
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