Last updated: October 7, 2026

Physics

Summary

The game keeps its rigid bodies in a physics world reached through the physics manager (0x0593d700 → +0x28 → +0x8). The world holds tables that everything else indexes into: bodies (0x90 bytes each, at +0x20), their motions (0x80 bytes each, at +0xe0), constraints (0x38 bytes each, at +0x128), and a list of listeners at +0x538 that are told when a body changes.

physics_instance_construct_01c0c2b0 (0x01c0c2b0) is the constructor of a physics instance: an object that owns a set of bodies in that world (a ragdoll or a breakable object would look like this; which one is still open). Reading it is a good lesson in how a constructor wires a new object into shared tables:

1. It asks the body-set constructor for its bodies, then moves every active body (flags +0x40 & 3) by the offset it was given.
2. It writes a 16-byte back-link for each of its bodies and constraints, and points the world's tables at them, so the world can find the instance from any body.
3. It copies the set's shape table (0x30 bytes per shape) into a buffer from a dedicated heap, handing it to a shape object, and builds a controller whose fixed frame step is 1/30 s and whose transform starts at the root body.
4. Unless the physics manager is in one of its two special modes (as it is while Iosefka's Clinic loads), it rescales each active body's four 16-bit motion values and tells the world's listeners about each body, removing listeners that are flagged for removal.
5. Last, it creates its own listener and a tracker, and collects the distinct motion types above 4 of its bodies.

How the motion values are rescaled

The four values are stored as the top halves of 32-bit floats (the format known as bfloat16): 16 bits holding a float's sign, exponent and the top of its mantissa. The code widens each back to a float by putting it in the upper half of a float's bit pattern, multiplies the first three by 0.2 and all four by 1.00390625, then keeps only the top 16 bits of each result again (an arithmetic shift of the bit pattern, then a saturating pack). It is a compact way to store floats at half the size, and an example of why a replacement has to reproduce the exact instructions: the truncation works on the float's bits, not its value.

Key functions

Address	Size	Name	Status	Notes
0x01c0c2b0	3222	physics_instance_construct_01c0c2b0	verified	physics instance constructor over a body set: back-links, shape copy, controller (step 1/30 s; 60 FPS patches 1/60), motion rescale, listeners

Structs and globals

• Physics manager (0x0593d700): world at +0x28 → +0x8; special-mode flags at +0x274 and +0x275.
• World: body table +0x20, motion table +0xe0, constraint table +0x128, listener list +0x538 (a tagged pointer: the low two bits are flags).
• Body (0x90 bytes): position +0x30, flags +0x40, motion index +0x68, back-link +0x88.
• Instance: body set +0x38, back-links +0x70/+0x78, shape object +0x88, controller +0x90 (frame step at +0x60), own listener +0x128.

Patch points

• The controller's frame step is 1/30 s; 60 FPS++ (and 90 FPS++, 60FPS (no deltatime)) make it 1/60 s. BB_TARGET_FPS=60 does the same.

Open questions

• What kind of object is a physics instance: ragdolls, breakables, or both?
• What do the physics manager's two special modes mean? Both are on while the clinic loads.