1Marrow Interaction Engine

The **1Marrow Interaction Engine** (or just the **Marrow Engine**), is a proprietary physics framework developed by Stress Level Zero for the Unity engine. Originating from BONEWORKS' mechanics, it contains all physics, solvers and logic used to create physics-based VR games such as BONELAB. Alex Knoll stated that 1Marrow is an internal framework and is unlikely to be licensable to third party studios.

## Development & Differences from BONEWORKS

### Hexabody vs Heptabody

*BONEWORKS* utilized the hexabody configuration, which consisted of a skeleton rig controlled by both the player's real-world movements influenced by a basic physics rig driven by six-point inverse kinematics and subsequent world interaction. Together, the real movement and physical feedback from the world drove the final pose solver for Ford.

1Marrow instead uses the updated Heptabody Configuration, consisting of a 7-point IK skeleton. Paired with a far more detailed and expansive physics asset (which covers the torso and head), it also can perform far more realistic inverse kinematics based on the player's movement. Additionally, the heptabody can be modified and configured to be changed to different body types and sizes.

The major changes include far more realistic collision. The Hexabody utilized basic collision shapes, and only gave collision to the hands, head, and foot-ball. However, the Heptabody has much more complex collisions that include the entire torso and jointed arms, as well as a detailed head mesh.

Hexabody's body shape and size was set - *BONEWORKS* scaled the player to Arthur Ford's proportions, while *BONELAB* does not. The Heptabody allows for modified movements while still keeping the IK and physics asset realistic.

## Function

The function of 1Marrow is not entirely explained, but snippets are located throughout *BONELAB,* explaining various functionality. The compiled notes and information can be found here. (Note that this information is presented in-universe, and thus was subject to modification to fit the game's lore and plot. A footnote has been provided for sections which have been modified from reality to fit the game's narrative.)

### Control

#### Virtual Crouching

Provides flexibility and accessibility in interacting with the world.

#### Locomotion

Traversing environments with a physically simulated body requires non-kinematic based locomotion. The physical inaccuracy of non-physics locomotion would create potential infinite forces. Body locomotion provides a more natural and try to universal rules method of movement. [sic]

#### Body Slots

Physical lock locations of the body provide immediate physical access to body-held items. Accuracy in grabbing location is increased due to Body Remapping.

#### Abstracted Inventory

Accessibility in self-interaction is a critical layer on top of the physical bodyslot points. Objects are held in parallel simulation until proxy-retrieved from abstracted inventory.

#### Force Pull

The void realms provide some paraphysical interaction options worthy of implementing in core interaction. Force pull/grab is an accessibility must for quicker confidence with object handling.

#### Two Handing

Elegant physics handling of objects requiring two hands is a cornerstone of controlling objects. Converting a physical open-loop (real world) body to the closed-loop (virtual) body is necessary for stable reactions. See Virtual Controller.

#### Full Body

A complete avatar body is required for physical interaction accuracy and immersive aesthetics. This is a quintessential aspect of inhabiting the void realms. See Rig Manager.

### Heptabody Configuration

#### Controller Rig

Controller Rig manages all incoming connections from real world hardware.

#### Real Hepta Rig

Realtime Hepta Skeleton works as a bind between the Controller Rig and the virtual Hepta Skeleton.

#### Virtual Hepta Rig

Simulated Hepta Skeleton contains all structural information for the virtual body.

#### Physics Rig

Physics Rig contains all the calculations, mass, and jointing for all body solver physics.

### Body Remapping

Physical proportions translate real-world kinesthetics to any virtual body. Height, chest, inseam, sacrum, and wingspan form the basis for remapping inverse kinematics.

### Avatar Stats

Physical proportions of an avatar must inform physical abilities and limits within MythOS.

#### Height

Determines an avatar's reach or ability to fit in vertically tighter spaces.

#### Mass

Avatar mass is calculated by the sum of limb proportions and circumference, against height.

#### Agility

A composite stat of limb proportion ratio to mass of an avatar will determine its agility, how quickly can the avatar change direction or accelerate.

#### Speed

Maximum locomotion velocity is a limitation measured by skeletal proportions.

#### Strength Upper

Upper body strength is measured by the avatar's wingspan proportional to the length of torso, mass, and height. This determines punching/lifting/pulling etc.

#### Strength Lower

Lower body strength is measured by the avatar's leg length proportional to the length of torso, mass, and height. This determines running/jumping etc.

#### Vitality

An avatar's ability to sustain repeated damage depends on mass, height, and circumference.

### Interaction

#### Object Mass

Accurate object mass is critical to physical believability in object interaction. Responsive handling of heavier mass objects depends on avatar stats.

#### Sounds

Impact, surface, grab, release, throw, mechanism interaction, action, ambient, item specific.

#### Simulation Scale

Safe range scale ranges usually from around 5cm-50cm depending on the object. Below this range runs the risk of physics step issues. Above this range generally creates cumbersome or clumsy interaction. Above this range enters mass scale ratio risks.

Range Examples
 Safe
 Risky
 Risky

#### Handling

**Pick Up** - proximity and importance measurement to determine pickup intent.

**Force Grab** - Measure between gaze, reach, importance to determine remote grab intent.

**Functionality** - Holdable objects must behave in a physically realistic manner with informed grip posing, secondary interactivity, and intelligent grip behavior.

**Shouldering** - Resting shoulder-able objects against the physics body while held creates a three-point VC chain for a more accurate "closed-loop" handling interaction.

**Throw** - Releasing objects on throw with physical weight requires a measurement of velocity over time for smarter release.

### Virtual Controller

The virtual controller's primary function is to inform the physics body on how to manipulate objects held with multiple force points. Transmitting physical force intention across realities can otherwise create anomalous physics behavior. Preventing unlimited forces and feedback loops is necessary for expectant physics interaction.

Advanced filtering considered for preventing opposing unintentional forces or optimizes force behavior when desirable. Stability and responsiveness prioritized in interaction.

### Vehicles / Seats

Highly experimental, additional R&D required for further data on vehicle operation. Continued development cycles necessary for broad determinations.

## Trivia

* The characters "*s u v a t*" in the logo are a reference to a set of equations for motion when acceleration is constant, and can be used to find an object's displacement, initial/final velocities, and acceleration.

## References

1. ↑ https://pastebin.com/rjiVUGJ9 -

	1. Q: What will the 1 Marrow interaction engine be? A unity asset?
	2. A: our internal mechanics
2. ↑ https://pastebin.com/rjiVUGJ9 -

	1. Q: Will 1marrow be available to license in the future?
	2. A: unlikely but unknown
3. ↑ This is the in-universe explanation. In reality, the inventory is simply stored until it is called to spawn whichever items it holds.
4. ↑ The first sentence is clearly not real, but the second sentence provides reasoning for force movements.
5. ↑ The second sentence is for narrative purposes.