Spatial variable standards

Spatial Variables are a powerful feature allowing you to define location-dependent values. To support seamless interaction between independently developed objects it is necessary to follow standards for naming, types, content and sampling of spatial variables.

This article collects several community-proposed standards made with the goal that other users - instead of creating their own - reuse them for compatibility with other creations.

Naming Conventions

To avoid the risk of naming conflicts it is recommended to follow the naming standard "Prefix.Variable" where a shared prefix groups related variables together.

Using PascalCase would make all future proposals consistent to the existing ones.

Sampling Mode

Standards should recommend a sampling mode where applicable.

Examples include:

HighestPriority: Only the value with the highest priority is considered. This will lead to abrupt transitions between areas.
Additive: All variables are added together. Variables with blend distance will avoid sharp transitions. It is not possible to create an area with an override. (priorities are ignored)
WeightedAverage: All variables are averaged. Variables with blend distance will avoid sharp transitions. It is not possible to create an area with an override. (priorities are ignored)
PrioritySortedBlend: This layers variables with higher priority on top of variables with lower priority. Variables with blend distance will avoid sharp transitions.

Default Value

Standards should recommend a sensible default value.

Configurable default values can be implemented by using dynamic variables of the "World" space with the same name as the spatial variable. (i.e. dynamic variable "World/Gravity" as a default for the spatial variable "Gravity")

This approach can also be used to extend existing standards for dynamic variables with location-based overrides.

Official Variables

The following variables are defaults used by FrooxEngine:


Variable	Type	Sampling Recommendation	Interpretation	Proposed by/when
Resonite.Audio.Filters	AudioDSP_Effect	Sample via the ReferenceSpatialVariableCollector	audio effects like reverb that are in effect in an area	Frooxius, 2025

As of 2025 spatial variables are a relatively recent feature which means that many of the community-made proposals are still young and may still be under construction. If you see a need for a new standard, feel free to add it to this page! You can discuss your ideas in detail on Discord or the Talk Page.

Simple Interactions

The following variables are made to be easily integrated into an object:

Variable	Type	Sampling Recommendation	Interpretation	Proposed by/when
Heat	float	Additive Default: 0	Positive: heat source Negative: heat sink suggested values: A few meters from a fire: 1 Cooking: 10 Slightly cold: -1 Freezing: -10	LucasRo7, 2025
Fire	bool	MaxPriority Default: false	sets things on fire	LucasRo7, alizard, Panda, 2025
Water	bool	MaxPriority Default: false	puts out fire and makes things wet	LucasRo7, Panda, 2025
Electric	bool	MaxPriority Default: false	shocks things or people, may turn devices on	LucasRo7, 2025
Wind	float3	Default: [0;0;0]	wind speed in m/s	LucasRo7, 2025

Physical Quantities

Temperature, pressure and other values can vary greatly between different locations. (i.e. temperature within fire vs. temperature of an ice cube)

Theoretically every such property could be made a spatial variable. The following proposals have been created from this idea.

Their usefulness varies: Some, like temperature or gravity, are more prominent in everyday interactions than others. (i.e. electric field)

Mature

The following proposals have been judged by their author as unlikely to need further changes and/or there are already items using them.


Variable	Type	Unit	Sampling Recommendation	Interpretation	Proposed by/when
Temperature ~~(formerly: Physics.Temperature)~~	Temperature	(included in type)	Mode: PrioritySortedBlend Default: dynamic variable World/Temperature 288.15K / 15°C	air/water/object temperature makes things freeze, boil or ignite can be measured with thermometers may be required for baking/cooking Simple games and interactive objects can use the following conditions: Freezing water: sampled <= 273.15K / 0°C Boiling water (sea level): sampled >= 373.15K / 100°C Cooking food: sampled >= 353K / 80°C for X minutes (higher temperature -> faster) Starting a fire: sampled >= 550K / 277°C A typical flame is around 1300K / 1027°C at its core and easily fulfills the requirements to start a fire! Realistic objects could use "real" temperatures but still be compatible with simplified objects: Igniting wood: sampled >= 553-613K / 280-340°C Igniting gasoline: sampled >= 493-733K / 220-460°C Igniting propane: sampled >= 743K / 470°C Wood flame (air): 1300K / 1027°C Gasoline flame: 1299K / 1026°C Propane flame (air): 1473-1973K / 1200-1700°C	TheAutopilot, 2025
Gravity ~~(formerly: Physics.Gravity)~~	float3	m/s²	Mode: PrioritySortedBlend Default: dynamic variable World/Gravity [0;-9.81;0] m/s²	global acceleration due to gravity accelerate users or items	TheAutopilot, 2025

In Progress

The following standards have been suggested by their authors but may need more work and/or adoption in practice.


Variable	Type	Unit	Sampling Recommendation	Interpretation	Proposed by/when
Physics.Pressure	float	Pa	Default: 101325 Pa	pressure expand or compress hollow objects Typical pressures for reference: sea level: 101325 Pa exponential decrease by 50% per 5400m altitude every 1m under water: add 9810 Pa	TheAutopilot, 2025
Physics.Force	float3	N	Default: [0;0;0] N	global force applied to all objects within the field	TheAutopilot, 2025
Physics.Density	float	kg/m³	Default: 1.225 kg/m³ (air)	density of the gas/liquid/solid at the sampled position detect if within vacuum (breathing) compute wind force together with variable "Wind"	TheAutopilot, 2025
Physics.ElectricField	float3	V/m	Default: [0;0;0] V/m Mode: Additive	vector of the global electric field at the sampled position	Papaltine, 2025
Physics.MagneticField	float3	T (Tesla)	Default: [0;0;0] T Mode: Additive	vector of the global magnetic field at the sampled position makes a compass point to another direction	Papaltine, 2025
Physics.ElectricPotential	float	V	Default: 0 V	electric potential allows measuring voltage between two points can be used to check if a user or item should be electrocuted	TheAutopilot, 2025

Retracted

The following proposals have been retracted by their author. (i.e. in favor of another one)


Variable	Type	Unit	Sampling Recommendation	Interpretation	Proposed by/when
~~Physics.Velocity~~	~~float3~~	~~m/s~~	~~Default: [0;0;0] m/s~~	~~global velocity of the gas or liquid at the sampled position~~ ~~compute wind force together with density~~	~~TheAutopilot, 2025~~ (retracted in favor of "Wind" by LucasRo7)

Location Descriptions

Variable	Type	Sampling Recommendation	Interpretation	Proposed by/when
Location.Tags	string	Default: null	space-separated list of tags describing location (recommended order: most general to most specific) Note: Simply checking Contains may lead to errors with partial matches!	Redd, 2025
Location.Slot	Slot	Default: null/Root (depends on use-case)	Slot representing the location a position is in This can be used to interact with dynamic impulses and dynamic variables.	TheAutopilot, 2025
Location.Indoors	bool	Default: false Blending: MaxPriority	describes whether a location is indoors	TheAutopilot, 2025
Location.Underwater	bool	Default: false Blending: MaxPriority	describes whether a location is underwater	TheAutopilot, 2025