Points that clipping creates along a feature's edges, other than at the
existing vertices, and the vertices of tiny polygon placeholders, are
not vertices of the original geometry, so they are now marked as not
being shared nodes instead of being looked up in the global list of
shared nodes when they are simplified. This could only change the output
where a vertex of some other feature happens to fall exactly on one of
these new points, and in practice none of them ever turned out to be
shared nodes.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P2nBqZisxNQfmEmon3vE9v
Geometry that was clipped to --clip-bounding-box while it was being
serialized can already have node states in its operation bytes, so the
unmasked comparison against VT_MOVETO and VT_LINETO failed to recognize
those vertices and lost track of where the following vertices began.
Also stop with an error instead of continuing if the operation is not
one that can appear in serialized geometry.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P2nBqZisxNQfmEmon3vE9v
Vertices that are already going to be kept, because they begin a ring
or are on the tile boundary, can't be affected by whether they are also
global shared nodes, so skip looking them up. These are most of the
vertices that clipping creates, which don't know their node state.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P2nBqZisxNQfmEmon3vE9v
With --no-simplification-of-shared-nodes, simplify_lines() used to offset
every vertex of every feature to world coordinates and check it against
the Bloom filter and the global sorted list of shared nodes, in every
tile at every zoom level.
Whether a vertex is a shared node depends only on its world coordinates,
so now it is found once, after the list of shared nodes has been made
and before the geometry is sorted, by a parallel pass over each reader's
geometry that marks each vertex in place, in the upper bits of its
serialized operation byte. Decoding puts that state into a new field of
draw (which still fits in 16 bytes), and it is carried through clipping,
the copies across the antimeridian at z0, and the geometry written for
the next zoom level. Polygon cleaning of coalesced features restores the
state of any output vertex with the same coordinates as an input vertex.
Vertices whose state is still unknown, because they were created by
clipping or polygon cleaning or came back from a prefilter, are still
looked up in the global list when they are simplified, so the output is
unchanged.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P2nBqZisxNQfmEmon3vE9v
Claude