broad_phase: the broad phase, and an overflow-free key hash - #13
Merged
Merged
Conversation
aephysics.broad_phase, Box3D's broad_phase.c in Aether: a dynamic tree per body type with the shapes' proxies keyed by type in the low bits, and the pair update after a step: the dynamic tree against itself through the sibling pairs a moved node touched (cross-subtree only, so no duplicates) and against the static and kinematic trees from a breadth-first seeding; the candidates culled by the pair set, filtered by the client's visitor, a compound's pair expanded to one per overlapping child through the client's compound lookups, and the keys sorted so the contacts come out in an order the trees cannot change. The reference filters and creates contacts inside its world; here the update leaves the keys for the client, which adopts them into the set. test_broad_phase.ae (ours; the reference covers this through its world tests): keys and the sort, a grid of dynamic boxes over a static ground with a kinematic platform against a brute force across the first update, a quiet update, moves, a removed pair, the filter, one body's shapes, a forced static proxy, a destroyed proxy, and a compound's pairs one per child. 36 checks. The hash under every set and map, core's key_hash, multiplied signed longs: undefined in the C underneath, and gcc at -O2 made two inlined copies disagree, so a key stored by one copy was not found by the other (the broad phase test caught it; the mesh's maps had passed by luck). It now mixes both halves in 32-bit products. The mesh builds move from 199 to 221 ms with it. bench/broad_phase.ae runs alone (the reference's update has no free-standing counterpart): 10,000 moving boxes at 4.6 ms a step. scripts/bench.sh runs a layer without a reference pair.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The thirteenth layer: Box3D's broad_phase.c as
aephysics.broad_phase, world-free.broad_phase_create/destroy/move_proxy, marks,test_overlap.update_broad_phase_pairs(bp, visitors, has_compounds): the moved-sibling walk of the dynamic tree against itself, the breadth-first seeding against the static and kinematic trees, the pair set cull, the client'sshould_pairgauntlet, a compound's pair expanded per overlapping child throughcompound_tree_of/compound_transform, the keys sorted and deduplicated; the client reads them withpair_key_count/pair_keyand adopts them withadd_pair. Single-threaded; the seeds and siblings keep the reference's order.test_broad_phase.ae: 36 checks against a brute force (first update, quiet update, moves, removed pairs, the filter, one body's shapes, a forced static proxy, a destroyed proxy, a compound's children).core.key_hashmultiplied signed longs (UB in C); at -O2 two inlined copies disagreed and a key stored by one was not found by the other. Rewritten in 32-bit products mixing both halves; the mesh's builds move from 199 to 221 ms.bench/broad_phase.aeruns alone (the reference's pair update lives inside its world);scripts/bench.shnow runs a layer without a reference pair. 10,000 moving boxes at 4.6 ms a step.