From d8cbb0c95bcb9670bec92d29ab522c63da9da9a0 Mon Sep 17 00:00:00 2001 From: Zwitschi Date: Tue, 10 Nov 2026 19:58:51 +0100 Subject: [PATCH] docs(vehicle): the visual and physics bodies are different vehicles SM_Vehicle_Body (hot hatch) is 150x400x122 (length along Y); SK_Vehicle_Sedan is 476x228x144 (length along X). They are built by different scripts and do not share a forward axis - the likely real cause of the reverse drive. MaxTorque sign was also a no-op. Next: reconcile the two meshes into one asset with one forward axis. --- MEMORY.md | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/MEMORY.md b/MEMORY.md index 9278ec7..fcaa211 100644 --- a/MEMORY.md +++ b/MEMORY.md @@ -1117,3 +1117,18 @@ Historical task context from 2026-11-09/10; later vehicle findings above may sup authoring is irrelevant. The inversion is in the **engine-torque / drive-force sign** (`FSimpleWheel`), not the assets. Next: check `GetEngineTorque()` sign, or override `SetupVehicle`/`ProcessMechanicalSimulation` in `UGigLineVehicleMovement` to negate the drive torque. + +## 2026-11-10 — Vehicle: the visual body and the physics body are different vehicles + +- `SM_Vehicle_Body` (the owner's **hot hatch** template, what the panels render) imports with + bounds **150 x 400 x 122 cm** — its length is along **Y**. `SK_Vehicle_Sedan` (the procedural + sedan that the Chaos solver drives) is **476 x 228 x 144** with the length along **X**. They + are built by different scripts (`vehicle_from_template.py` vs `vehicle_build.py`) and do not + even share a forward axis. +- This is almost certainly the real story behind the "reverse" drive: the solver applies the + drive force forward on the skeletal sedan (+X) while the visible car's nose is on a different + axis, so a forward physics motion reads as a sideways/backward car. `MaxTorque = -500` was also + a no-op (the torque curve normalises the magnitude), ruling out the engine torque sign. +- Next step is not more solver tracing: reconcile the two meshes — drive the **hot hatch** (make + it skeletal, or rebuild `SK_Vehicle_Sedan` to match the hot hatch's axis and dimensions) so the + visible and physics cars are one asset with one forward axis.