The in-place-only arena still fell back to a full batched rebuild on add/remove —
re-uploading the entire wire instance buffer, which on a drawing whose wires
expand to millions of segments (~265 MB) stalls ~1s per add/remove on a
shared-memory GPU. Only move/edit avoided it.
Add append/tombstone so add/remove patch the instance buffer too: a new or
segment-count-changed entity bump-allocates a slab at the tail (buffers carry
1.5x headroom); an erased entity is tombstoned (blanked at const slot 0). The
huge instance buffer only grows/blanks by the changed entity.
Three correctness points make add/remove safe (each verified by an adversarial
review, findings folded in):
- draw_depth_map normalises each entity`s z-bias by the block entity count, so a
structural change re-scales every entity`s bias. Keep a CPU mirror of the const
array; on any structural change refresh every slab`s draw_depth and re-upload
the small (~1 MB) const buffer, leaving the instance buffer untouched.
- a tail-appended entity draws last, which only mis-orders wires whose overlap
resolves by submission order rather than the z-bias: transparency, and 3D-solid
fallback edges (Solid3D/Region/Body/Surface are excluded from draw_depth_map, so
their opaque edges share depth 0). `append_unsafe` bails to a full rebuild when
the set contains either.
- an in-place edit also flushes its consts to the GPU (a colour change is not
structural, so the whole-buffer refresh would otherwise skip it).
Still behind OCS_WIRE_GPU_PATCH (default off); every uncertain case returns false
and the caller does the identical full rebuild, so correctness never rides on the
fast path.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
On a geometry edit the resident set gets a fresh content id, so the batched wire
path (build_wire_buffers) re-emits and re-uploads EVERY wire instance — the whole
buffer even when one line moved. Behind the OCS_WIRE_GPU_PATCH flag (default off,
native only), add a persistent per-entity instance arena: one long-lived
VERTEX|COPY_DST instance buffer + its WireConst storage, with a per-entity slab
table. An in-place edit (move / rotate / scale / colour — same segment count)
becomes a queue.write_buffer of just that entity`s slab.
Scope is deliberately IN-PLACE ONLY. draw_depth_map normalises each entity`s
draw-order z-bias by the block`s entity count, so an Add or Remove re-scales EVERY
entity`s z-bias — which a per-slab patch can`t honour — and a segment-count change
relocates the entity. patch() returns false for any of those (and for mesh-edge /
scissored sets), and the caller falls back to the identical full batched rebuild,
so correctness never rides on the fast path. An adversarial review of an earlier
append/tombstone design surfaced exactly these draw-order hazards; restricting to
in-place removes them while keeping the common interactive-edit win.
The Scene hands the changed handles to the arena via model_wire_gpu_patch,
recorded by try_resident_patch for the Model block and matched by content id in
prepare(); scissored paper viewports and mixed 2D/3D sets keep the batched path.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
