Hakan SevenandClaude Sonnet 4.6
d1ecaf4695
Add two complementary render caches that make mouse navigation essentially free regardless of file size: Option A – Wire tessellation cache: entity_wires_arc() caches the tessellated Vec<WireModel> keyed by geometry_epoch and returns an Arc, so navigation frames (no preview wires) incur zero Vec clones and zero tessellation work. Primitive::wires changed to Arc<Vec<WireModel>>. Option B – GPU buffer cache: Pipeline stores cached_epoch; prepare() skips all upload_wires/hatches/images/meshes calls when the epoch is unchanged, writing only the 192-byte camera uniform instead. geometry_epoch is a process-wide AtomicU64 incremented by every Scene mutation (add/erase entity, selection, layer visibility, layout switch, populate_*, grip, transform, copy, clear, preview wires). Using a global counter rather than a per-scene counter prevents two tabs that happen to have the same local bump count from sharing a cached_epoch value, which was causing the first file's geometry to remain on screen after opening a second file. Co-Authored-By: Claude Sonnet 4.6 <[email protected]>
4.8 KiB
Performance Optimization Plan
Problem
The application lags severely when large files are open — even simple mouse movement causes noticeable frame drops.
Root Cause
Every frame (triggered by any mouse event), Iced calls shader::Program::draw() → build_primitive().
This function:
- Re-tessellates every entity from scratch —
wires_for_block()iterates all document entities and callstessellate_one()for each, every single frame. - Recreates all GPU buffers —
prepare()callsupload_wires/hatches/images/meshes(), each of which allocates newwgpu::Bufferobjects for every entity, every frame. - Linear-scans all objects to find
SortEntitiesTableon every frame.
During pure mouse navigation (pan/zoom), nothing in the geometry data changes — only the camera matrix (uniforms) changes. Despite this, all work above is repeated for every mouse-move event.
Option A — Wire Tessellation Cache ✅ Implemented
Status: Done
Added wire_cache: RefCell<Option<(u64, Arc<Vec<WireModel>>)>> to Scene.
entity_wires_arc() checks the cache first; if geometry_epoch matches it returns the cached
Arc (O(1) refcount bump). On a cache miss it tessellates, wraps the result in Arc, stores it,
and returns a clone of the Arc.
build_primitive() uses entity_wires_arc() directly:
- No preview wires (navigation): stores the Arc as-is — zero Vec clones, zero tessellation.
- Command active (preview wires present): clones the cached entity Vec once, appends preview/interim wires, wraps in a new Arc — only one allocation instead of full tessellation.
Primitive::wires changed from Vec<WireModel> to Arc<Vec<WireModel>>.
Impact: During navigation in large files the per-frame cost of the wire step drops from O(entities × tessellation) to O(1). Combined with Option B the GPU upload is also skipped, making navigation frames nearly free regardless of file size.
Option B — GPU Buffer Cache ✅ Implemented
Status: Done
Add a geometry_epoch: u64 counter to Scene. Bump it whenever geometry-affecting state changes.
Carry the epoch through Primitive to Pipeline, which stores cached_epoch: u64.
In prepare():
- Always upload uniforms (camera changes every frame).
- Skip geometry buffer uploads (
upload_wires/hatches/images/meshes) whengeometry_epoch == cached_epoch. - After uploading, set
pipeline.cached_epoch = geometry_epoch.
Impact: During navigation, only a single 192-byte uniform write reaches the GPU instead of re-creating thousands of buffers. Fixes mouse-movement lag in large files.
Difficulty: Medium. Requires bumping the epoch in all geometry-mutation paths.
Epoch bump locations
| Method | Location |
|---|---|
add_entity() |
scene/mod.rs |
erase_entities() |
scene/mod.rs |
populate_hatches_from_document() |
scene/mod.rs |
populate_images_from_document() |
scene/mod.rs |
populate_meshes_from_document() |
scene/mod.rs |
set_preview_wires() |
scene/mod.rs |
clear_preview_wire() |
scene/mod.rs |
set_interim_wire() |
scene/mod.rs |
select_entity() |
scene/mod.rs |
deselect_all() |
scene/mod.rs |
expand_selection_for_groups() |
scene/mod.rs |
toggle_layer_visibility() |
scene/mod.rs |
transform_entities() |
scene/mod.rs |
copy_entities() |
scene/mod.rs |
apply_grip() |
scene/mod.rs |
clear() |
scene/mod.rs |
Option C — Parallel Tessellation (Rayon)
Status: Planned
Replace the sequential .flat_map(|e| self.tessellate_one(e)) chain in wires_for_block() with
rayon::par_iter().
Impact: Spreads tessellation across all CPU cores. Improves file-open time and post-edit refresh. Does not fix per-frame navigation lag (Option A/B address that).
Difficulty: Easy. Requires making tessellate_one free of interior mutability, or collecting
into a Vec first then parallel-processing.
Option D — Frustum / Viewport Culling
Status: Planned
Build a spatial index (R-tree or uniform grid) over entity bounding boxes.
During wires_for_block(), skip entities whose bounding box lies entirely outside the camera frustum.
Impact: Dramatic speedup for large drawings when zoomed in — only visible entities are tessellated and uploaded. No benefit when the full drawing is visible.
Difficulty: Hard. Requires maintaining an up-to-date spatial index and computing per-entity bounding boxes for all entity types.
Option E — SortEntitiesTable Scan Cache
Status: Planned
Cache the result of the SortEntitiesTable lookup that currently performs a linear scan over all
objects on every wires_for_block() call.
Impact: Minor. Removes one O(objects) scan per frame. Low priority compared to A–D.
Difficulty: Easy.