GLEVALPOINT(3G)

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

C SPECIFICATION
void glEvalPoint1( GLint i )
void glEvalPoint2( GLint i,
	GLint j )

PARAMETERS

i   Specifies the integer value for grid domain variable i.

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

DESCRIPTION
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 dot DELTA(u) + u1 );

where

DELTA(u) = ( 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 dot DELTA(u) + u1 is exactly u2.

In the two-dimensional case, glEvalPoint2, let

    DELTA(u) = ( u2 - u1 ) / n

    DELTA(v) = ( v2 - v1 ) / m,

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

    glEvalCoord2( i dot DELTA(u) + u1, j dot DELTA(v) + v1 );

The only absolute numeric requirements are that if i=n, then the value computed from i dot DELTA(u) + u1 is exactly u2, and if j=m, then the value computed from i dot DELTA(v) + v1 is exactly v2.

ASSOCIATED GETS
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

SEE ALSO
glEvalCoord, glEvalMesh, glMap1, glMap2, glMapGrid