glEvalPoint.3G - Man Page

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$·\Delta u+u_1$ );

where

$\Delta u=(u_2-u_1)/n$

and $n$, $u_1$, and $u_2$ are the arguments to the most recent glMapGrid1 command. The one absolute numeric requirement is that if $i=n$, then the value computed from  $i·\Delta u+u_1$ is exactly $u_2$.

In the two-dimensional case, glEvalPoint2, let

$\Delta u=(u_2-u_1)/n$

$\Delta v=(v_2-v_1)/m,$

where $n$, $u_1$, $u_2$, $m$, $v_1$, and $v_2$ are the arguments to the most recent glMapGrid2 command. Then the glEvalPoint2 command is equivalent to calling

glEvalCoord2( i$·\Delta u+u_1$, j$·\Delta v+v_1$ );

The only absolute numeric requirements are that if $i=n$, then the value computed from $i·\Delta u+u_1$ is exactly $u_2$, and if $j=m$, then the value computed from  $i·\Delta v+v_1$ is exactly $v_2$.

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)

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).