glEvalPoint2 function

The glEvalPoint1 and glEvalPoint2 functions generate and evaluate a single point in a mesh.

Syntax


void glEvalPoint2(
   GLint i,
   GLint j
);

Parameters

i

The integer value for grid domain variable i.

j

The integer value for grid domain variable j .

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 Δu +u₁ );

where

Δu = (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 Δu + u₁ ) is exactly u₂ .

In the two-dimensional case, glEvalPoint2, let

Δu = (u₂ u₁ )/n

Δv = (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 Δu + u₁ , j Δv + v₁ );

The only absolute numeric requirements are that if i=n, then the value computed from (i Δu + u₁ ) is exactly u₂ , and if j = m, then the value computed from (j Δv + 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

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Gl.h

Library

Opengl32.lib

DLL

Opengl32.dll

See also

glEvalCoord
glEvalMesh
glGet
glMap1
glMap2
glMapGrid

 

 

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