Maris:
> Unfortunately this is a quite big problem for GRASS if nobody
> from -dev ML can not explain how GRASS internal stuff works :(
It's not so bad, Radim did leave notes. e.g. in lib/vector/Vlib/buffer.c in
the case of public functions they are even Doxygen-ized so they appear in the
programmer's manual. For me "grep" does the job.
/*!
\brief Create parrallel line
\param InPoints input line
\param distance create parrallel line in distance
\param tolerance maximum distance between theoretical arc and polygon segments
\param rm_end remove end points falling into distance
\param[out] OutPoints output line
\return
*/
void
Vect_line_parallel ( ... )
{
....
}
here is the relevant code:
Vect_line_buffer()
....
dangle = 2 * acos( 1-tolerance/fabs(distance) ); /* angle step */
parallel_line()
....
atol = 2 * acos( 1-tol/fabs(d) );
....
/* TODO: a <= PI can probably fail because of representation error */
if ( a <= PI && a > atol)
{
na = (int) (a/atol);
atol2 = a/(na+1) * side;
for (j = 0; j < na; j++)
{
av+=atol2;
nx = x[i+1] + fabs(d) * cos(av);
ny = y[i+1] + fabs(d) * sin(av);
Vect_append_point ( nPoints, nx, ny, 0 );
}
}
Hamish
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