HP c3700 - Workstation, Reference Manual, Page: 143 / 486

E
glEvalMesh
Chapter 5
143
glEvalMesh
glEvalMesh1, glEvalMesh2
: compute a one- or two-dimensional grid of points or
lines.
C Specification
void glEvalMesh1(
GLenum mode,
GLint i1,
GLint i2)
void glEvalMesh2(
GLenum mode,
GLint i1,
GLint i2,
GLint j1,
GLint j2)
Parameters
mode In glEvalMesh1, specifies whether to compute a one-dimensional mesh
of points or lines. Symbolic constants GL_POINT and GL_LINE are
accepted.
i1, i2 Specify the first and last integer values for grid domain variable i.
mode In glEvalMesh2, specifies whether to compute a two-dimensional mesh
of points, lines, or polygons. Symbolic constants GL_POINT, GL_LINE,
and GL_FILL are accepted.
i1, i2 Specify the first and last integer values for grid domain variable i.
j1, j2 Specify the first and last integer values for grid domain variable j.
Description
glMapGrid and glEvalMesh are used in tandem to efficiently generate and evaluate a
series of evenly-spaced map domain values. glEvalMesh steps through the integer
domain of a one- or two-dimensional grid, whose range is the domain of the evaluation
maps specified by glMap1 and glMap2. mode determines whether the resulting vertices
are connected as points, lines, or filled polygons.
In the one-dimensional case, glEvalMesh1, the mesh is generated as if the following code
fragment were executed:
glBegin (type);
for (i = i1; i
≤
i2; i += 1)
glEvalCoord1(i-
∆
u + u
1
)
glEnd();
where
∆
u = (u
2
−
u
1
) / n