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-rw-r--r--research/tech-stack.org10
1 files changed, 9 insertions, 1 deletions
diff --git a/research/tech-stack.org b/research/tech-stack.org
index ce0a9c1..3e43e44 100644
--- a/research/tech-stack.org
+++ b/research/tech-stack.org
@@ -436,6 +436,12 @@ my_mod/
* Deterministic Simulation Design
+NOTE: the authoritative plan is =research/deterministic-physics.org=. The
+section below predates the custom solver and assumes Box2D owns the simulation.
+It does not: the game is decided by the mass-spring solver in
+=src/game/build_graph.cpp=, and Box2D is idle. The determinism work targets that
+solver (strict IEEE-754 float, owned transcendentals), not Box2D.
+
For lockstep multiplayer, the simulation must be exactly identical on all
machines.
@@ -474,7 +480,9 @@ Projects to study during development:
* Open Questions
-- [ ] Fixed-point math fallback vs trusting Box2D v3 determinism
+- [X] Fixed-point math fallback vs trusting Box2D v3 determinism — resolved:
+ strict IEEE-754 float on the custom solver, fixed-point held in reserve. See
+ =research/deterministic-physics.org=.
- [ ] Exact rope simulation approach within Box2D (distance joints? soft
constraints? custom spring?)
- [ ] Fire propagation model (graph traversal along connected flammable