Интерактивная система просмотра системных руководств (man-ов)
glEvalPoint (3)
>> glEvalPoint (3) ( Разные man: Библиотечные вызовы )
NAME
glEvalPoint1, glEvalPoint2
- generate and evaluate a single point in a mesh
C SPECIFICATION
void glEvalPoint1(
GLint i )
void glEvalPoint2(
GLint i,
GLint j )
delim $$
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$^cdot^DELTA u ~+~ u sub 1$ );
where
$DELTA u ~=~ ( u sub 2 - u sub 1 ) ^/^ n$
and $n$, $u sub 1$, and $u sub 2$
are the arguments to the most recent glMapGrid1 command.
The one absolute numeric requirement is that if $i~=~n$,
then the value computed from
$i ^cdot^ DELTA u ~+~ u sub 1$ is exactly $u sub 2$.
In the two-dimensional case, glEvalPoint2, let
$DELTA u ~=~ mark ( u sub 2 - u sub 1 ) ^/^ n$
$DELTA v ~=~ mark ( v sub 2 - v sub 1 ) ^/^ m,$
where $n$, $u sub 1$, $u sub 2$, $m$, $v sub 1$, and $v sub 2$
are the arguments to the most recent glMapGrid2 command.
Then the glEvalPoint2 command is equivalent to calling
glEvalCoord2( i$^cdot^DELTA u ~+~ u sub 1$, j$^cdot^DELTA v ~+~ v sub 1$ );
The only absolute numeric requirements are that if $i~=~n$,
then the value computed from
$i ^cdot^DELTA u ~+~ u sub 1$ is exactly $u sub 2$,
and if $j~=~m$, then the value computed from
$i ^cdot^DELTA v ~+~ v sub 1$ is exactly $v sub 2$.
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
