glEvalPoint.3G man page

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 · Δu+u1 );

where

Δu=(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 · 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 command. Then the glEvalPoint2 command 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  i · Δv+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(3G), glEvalMesh(3G), glMap1(3G), glMap2(3G), glMapGrid(3G)

Referenced By

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

The man pages glEvalPoint1.3G(3) and glEvalPoint2.3G(3) are aliases of glEvalPoint.3G(3).