v.parallel2 cycles

[akbgf]

GRASS-7.0 r44543

There are occasions that v.parallel can not create parallel lines to a line, v.parallel cycles forever.

Attached please find a small raster r35.txt and vector v35.txt which has a line and a centroid. The following sequence of commands will create an infinite loop:

r.in.ascii -i --overwrite input=r35.txt output=r35
v.in.ascii --overwrite input=v35.txt output=v35 format=standard fs='space'
v.parallel -b input=v35 layer=-1 output=v35b distance=10 side=both --overwrite

Andres Kuusk, Tartu Observatory, Estonia, andres@…

[akbgf]

Raster 26x37 (clos-rows)

[akbgf]

ASCII vector: 1 line, 1 centroid

[yawl]

The function

void link__set_next(VOID_T * a, VOID_T * b) 

in lib/linkm/next.c corrupted the

struct Slink
{
    double x;
    struct Slink *next;
};

defined in lib/vector/Vlib/poly.c by modifying x instead of *next.

The patch is attached as grass.diff

[yawl]

Patch

[mmetz]

Applies to v.parallel2, not to v.parallel.

[neteler]

v.parallel2 only exists in GRASS 6, downgrading milestone.

[mmetz]

Replying to neteler:

v.parallel2 only exists in GRASS 6, downgrading milestone.

v.parallel2 has been renamed to v.parallel in GRASS 7, restoring milestone.

[martinl]

Seems to be fixed in G74.