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glEvalPoint2 function

Applies to: desktop apps only

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

Minimum supported server

Windows 2000 Server

Header

Gl.h

Library

Opengl32.lib

DLL

Opengl32.dll

See also

glEvalCoord
glEvalMesh
glGet
glMap1
glMap2
glMapGrid

 

 

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Build date: 3/6/2012

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