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Manual Reference Pages  - GLEVALPOINT (3G)

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glEvalPoint1, glEvalPoint2 - generate and evaluate a single point in a mesh

CONTENTS

C Specification
Parameters
Description
Associated Gets
See Also

void glEvalPoint1( GLint i )

void glEvalPoint2( GLint i,

                 GLint j )

i	Specifies the integer value for grid domain variable i.
j	Specifies the integer value for grid domain variable j ( glEvalPoint2 only).

 glMapGrid and  glEvalMesh are used in tandem to efficiently generate and evaluate a series of evenly spaced map domain values.  glEvalPoint can be used to evaluate a single grid point in the same gridspace that is traversed by  glEvalMesh. Calling  glEvalPoint1 is equivalent to calling

	glEvalCoord1( i . DELTAu + u1 );

DELTAu = (u₂-u₁) / n

and n, u₁, and u₂ are the arguments to the most recent  glMapGrid1 command. The one absolute numeric requirement is that if i = n, then the value computed from i . DELTAu + u₁ is exactly u₂.

In the two-dimensional case,  glEvalPoint2, let

where n, u₁, u₂, m, v₁, and v₂ are the arguments to the most recent  glMapGrid2 command. Then the  glEvalPoint2 command is equivalent to calling

 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

 glEvalCoord(3G),  glEvalMesh(3G),  glMap1(3G),  glMap2(3G),  glMapGrid(3G)

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