glLineStipple   - specify the line stipple pattern  C
Specification    void glLineStipple( GLint factor,
GLushort pattern )     factor   Specifies a multiplier for each
bit in the line stipple pattern.            If factor is 3, for
example, each bit in the pattern will be used            three
times before the next bit in the pattern is used.  factor is
clamped to the range [1, 256] and defaults to one.    pattern
Specifies a 16-bit integer whose bit pattern determines which
fragments of a line will be drawn when the line is rasterized.
Bit zero is used first, and the default pattern is all ones.
Line stippling masks out certain fragments produced by
rasterization; those   parameters: the 16-bit line stipple
pattern pattern, the repeat count   factor, and an integer
stipple counter s.    Counter s is reset to zero whenever
glBegin is called, and before each line   segment of a
glBegin(GL_LINES)/glEnd sequence is generated.  It is
incremented after each fragment of a unit width aliased line
segment