JBeam Reference

1 Parts
2 Basic sections of a part
3 Comments in JBeam

This page is the basic reference book to get started building JBeam files. It covers the required and optional settings in every section, along with a quick description of what the settings do, and when available, links to more in depth explanations.

Parts

The jbeam system is designed to split the vehicle up into different parts. Each part is a block of jbeam that is read and loaded together. One can think of a part just like the part of a car; a door, fender, hood, etc. Any object that exists as a part of the vehicle can be a part in jbeam. Parts are organized into a hierarchy by use of the slot system. It does not matter which .jbeam file the part is contained in, or what the name of the .jbeam file is, as long as it is in the vehicle folder. This hierarchy design is important so that, for example, you can only load a wheel once you have loaded the suspension that it would connect to.

In jbeam, a part looks like this:

{
"example_part": {
        "information":{
        "authors":"example",
        "name":"Example",
        "value":5000000000000000,
        },
        "slotType" : "main",
        "slots": [
            ["type", "default", "description"]
        ],
        "refNodes":[
            ["ref:", "back:", "left:", "up:"]
        ],
        "flexbodies": [
             ["mesh", "[group]:", "nonFlexMaterials"],
        ],
        "nodes": [
            ["id", "posX", "posY", "posZ"],
        ],
        "beams": [
            ["id1:", "id2:"],
        ],    
        "triangles": [
            ["id1:","id2:","id3:"],
        ],
        "quads": [
            ["id1:", "id2:", "id3:", "id4:"],
        ],
    },
}

The very first and last curly brackets {} define the start and end of the file. Inside of these is another set of curly brackets. Within those, one can see a single part, with a part name "example_part". All of the data inside of the second set of curly brackets is read as a single part and given that name. In the above example part, there are a bunch of "sections" shown empty, except for a single line called the "header". All of the data of a part is placed within these sections.

Basic sections of a part

information

The information section defines some basic information about the part itself

example of an information section:

"information":{
    "authors":"BeamNG",
    "name":"Frame",
    "value":10000,
}

Name	Type	Optional	Default Value	Description
name	string	optional	""	Defines the name of the part
authors	string	optional	""	Defines the authors of the part
value	number	optional	n/a	Defines the value (cost) of the part

slots

Name	Type	Optional	Default Value	Description
type	string	required	n/a	Defines the "type" for this slot. The game will look for parts with a "slotType" which matches "type", and allow those matching parts to be loaded
default	string	required	n/a	The name of the default part to be loaded if one has not been chosen by a configuration file or by the parts selector/garage
description	string	optional	type	The description of this part, shown as description text in the parts selector/garage
nodeOffset	float3	optional	0,0,0	The offset of nodes and flexbodies of this slot
coreSlot	string	optional	n/a	If enabled, the choice to have the part empty is removed from the part selector/garage

refNodes

Example of reference nodes:

    "refNodes":[
        ["ref:", "back:", "left:", "up:", "leftCorner:", "rightCorner:"]
        ["fr9", "fr10", "fr9l", "fr11", "f7ll", "f7rr"]
    ],

This section defines a coordinate system from the vehicle nodes, so that the game can know the location and rotation of the vehicle. This reference is used by the cameras, the A.I, vehicle spawning, and also to trigger checkpoints in scenarios.

It is mandatory to have this section on the vehicle at all times!

Name	Type	Optional	Default Value	Description
ref	string	required	n/a	A node near the center and lowest point of the vehicle body (it doesn't need to be in the 0,0,0 node position, but usually is close to it)
back	string	required	n/a	A node directly behind the ref node (y axis)
left	string	required	n/a	A node directly left of the ref node (x axis)
up	string	required	n/a	A node directly above the ref node (z axis)
leftCorner	string	required	n/a	A node at the front left corner of the vehicle Used to trigger checkpoints.
rightCorner	string	required	n/a	A node at the front right corner of the vehicle. Used to trigger checkpoints.

nodes

Name	Type	Optional	Default Value	Description
id	string	required	n/a	Defines the node name
posX	number	required	n/a	The X (left/right) position in 3D space
posY	number	required	n/a	The Y (forward/back) position in 3D space
posZ	number	required	n/a	The Z (up/down) position in 3D space
nodeWeight	number	optional	options.nodeWeight	The weight of the node (kg)
collision	boolean	optional	true	If the node can collide with the world
selfCollision	boolean	optional	false	If the node can collide with the vehicle
group	string	optional	n/a	Groups a select set of nodes into a group
frictionCoef	number	optional	1.0	Friction coefficient of the node
nodeMaterial	string/bitmask	optional	options.nodeMaterial	Material of the node. Affects particles, skidmarks and sounds. Values used: "\|NM_RUBBER", "\|NM_METAL", "\|NM_PLASTIC", "\|NM_GLASS"
fixed	boolean	optional	false	Set to true to create a node that is locked in 3D space using its absolute coordinates
surfaceCoef	number	optional	0.1	Makes a node have more or less drag area in ground models with depth
volumeCoef	number	optional	0.1	Makes a node more or less buoyant in ground models with depth
pairedNode	number / node ID	optional	null	This can be used to i.e. link double tires together

beams

Anisotropic

Anisotropic beams have a special non linear behavior allowing different spring and damp if the beam is expanded or contracted. Special parameters are as follows:

Name	Type	Optional	Default Value	Description
springExpansion	number	optional	options.beamSpring	Spring of the beam when the beam has expanded beyond spawned length (N/m).
dampExpansion	number	optional	options.beamDamp	Damp of the beam when the beam has expanded beyond spawned length (N/m/s).
beamLongBound	number	optional	infinity
transitionZone	number	optional	0	This defines a range where the spring and damp move to springExpansion and dampExpansion. By default, the beam properties change instantly beyond spawned length, but adding transitionZone causes the values to ramp up over a zone. 0.1 would create a zone of 10% of beam spawned length.

Bounded

Bounded beams are a special type of beam that can change spring and damping depending on length and velocity. They are primarily used for shock absorbers and collision limiters. Once a bounded beam has reached a bound, its properties begin to change from the basic property to the limit property over a 1m distance. Use of bounded beams should be minimized since their advanced properties come with a performance cost. Special parameters are as follows:

Name	Type	Optional	Default Value	Description
beamLongBound	number	optional	1.0	How far the beam can expand before limit properties begin to apply. 0.0 would mean that the limit properties begin to apply as soon as the beam expands. 0.5 would mean that the beam can expand to 150% of its spawned length before limit properties begin to apply. 1.0 would mean that the beam can expand to 200% of its spawned length before limit properties begin to apply.
beamShortBound	number	optional	1.0	How short the beam can go before limit properties begin to apply. 0.0 would mean that the limit properties begin to apply as soon as the beam contracts. 0.5 would mean that the beam can contract to 50% of its spawned length limit properties begin to apply. 1.0 would mean that the beam can contract its entire length before limit properties begin to apply.
beamLimitSpring	number	optional	1.0	The spring that begins to be applied when the beam length reaches longBound or shortBound (N/m).
beamLimitDamp	number	optional	1.0	The damping that begins to be applied when the beam length reaches longBound or shortBound (N/m/s).
beamLimitDampRebound	number	optional	1.0	The damping that begins to be applied when the beam length reaches longBound or shortBound (N/m/s), but only when rate of expansion is > 0. beamLimitDamp will continue to affect the beam when rate of contraction is > 0 and the beam has reached a bound.
beamDampRebound	number	optional	beamDamp	The damping value applied only when the beam's rate of expansion is > 0 (N/m/s). beamDamp will continue to affect the beam when rate of contraction is > 0.
beamDampFast	number	optional	beamDamp	The damping value for the beam when the beam's rate of contraction or expansion is > beamDampVelocitySplit (N/m/s).
beamDampReboundFast	number	optional	beamDampRebound	The rebound damping value for the beam when the beam's rate of expansion is > beamDampVelocitySplit (N/m/s). beamDampFast will continue to affect the beam when rate of contraction is > beamDampVelocitySplit.
beamDampVelocitySplit	number	optional	infinity	The rate (m/s) of contraction/expansion over which beamDampFast and beamDampReboundFast take effect (m/s).

Support

Support beams are a special type of beam that can only resist compression. They can also break automatically at a set length. Primarily used for collision limiters. Special parameters are as follows:

Name	Type	Optional	Default Value	Description
beamLongBound	number	optional	1.0	When this bound is exceeded, the beam automatically breaks. 0.0 would mean the beam breaks if it expands at all. 0.5 would mean the beam breaks after expanding to 150% of its spawned length. 1.0 would mean the beam breaks after expanding to 200% of its spawned length.

Pressured

Pressured beams are mainly used in the hubWheel tire model to simulate air pressure with beams. Special parameters are as follows:

Name	Type	Optional	Default Value
pressure	number	optional
surface	number	optional	1.0
volumeCoef	number	optional	1.0
maxPressure	number	optional

L-Beam

L-Beams are primarily used in pressureWheels since 0.5.2.0. They are a type of beam that acts like an angular spring between two other beams. Special note: L-beams do not have deform or strength properties, but can break when either of the beams that form the "L" break. Special parameters are as follows:

Name	Type	Optional	Default Value	Description
id3	string	required	n/a	Name of the third node. The third node must already be connected to nodes [id1] and [id2] with beams. Any change in angle between beams [id1,id3] and [id2,id3] is then resisted by the L-Beam from [id1,id2]. Example L-Beam definition: ["node_id1","node_id2",{"id3:":"node_id3"}],

flexbodies

Flexbodies are the meshes that are mapped to your nodes. Without them, there's nothing to look at.

example of a basic flexbodies section:

"flexbodies": [
     ["mesh", "[group]:", "nonFlexMaterials"],
     ["barstow_trunk", ["barstow_trunk"]],
     ["barstow_lettering_barstow", ["barstow_trunk"]],
],

example of a flexbodies section with positioning:

"flexbodies": [
     ["mesh", "[group]:", "nonFlexMaterials"],
     //Rims
     ["offroadwheel_01a_17x9", ["wheel_FR","wheelhub_a_FR","wheelhub_b_FR"], [], {"pos":{"x":-0.8375, "y":-1.463, "z":0.46}, "rot":{"x":0, "y":0, "z":180}, "scale":{"x":1, "y":1, "z":1}}],
     ["offroadwheel_01a_17x9", ["wheel_FL","wheelhub_a_FL","wheelhub_b_FL"], [], {"pos":{"x": 0.8375, "y":-1.463, "z":0.46}, "rot":{"x":0, "y":0, "z":0}, "scale":{"x":1, "y":1, "z":1}}],
     //Tires
     ["offroadtire_01a_17x9_33", ["wheel_FR","wheelhub_a_FR","wheelhub_b_FR"], [], {"pos":{"x":-0.8375, "y":-1.463, "z":0.46}, "rot":{"x":0, "y":0, "z":0}, "scale":{"x":1, "y":1, "z":1}}],
     ["offroadtire_01a_17x9_33", ["wheel_FL","wheelhub_a_FL","wheelhub_b_FL"], [], {"pos":{"x": 0.8375, "y":-1.463, "z":0.46}, "rot":{"x":0, "y":0, "z":0}, "scale":{"x":1, "y":1, "z":1}}],
],

Name	Type	Optional	Default Value	Description
mesh	string	required	n/a	Name of the mesh (as named in the .dae file)
group	array	required	n/a	Array of node groups this flexbody will bind to
nonFlexMaterials	array	optional		nonFlexMaterials is a deprecated legacy feature that is not used or usable anymore
pos	float3	optional	0,0,0	The position offset of the flexbody
rot	float3	optional	0,0,0	The rotation of the flexbody
scale	float3	optional	1,1,1	The scale offset of the flexbody

triangles

Triangles are a type of surface with collision, drag/lift, and pressure/buoyancy effects. A triangle is defined between three nodes. The order the nodes are defined (clockwise or counterclockwise) determines which direction the triangle faces, important for collision and pressure/buoyancy behavior.

example of a basic triangles section:

"triangles": [
      ["id1:", "id2:", "id3:"],
      {"dragCoef":10},
      {"liftCoef":100},
      ["n1","n2","n3"],
],

example of a triangles section with a pressureGroup:

"triangles": [
      ["id1:", "id2:", "id3:"],
      {"dragCoef":10},
      {"pressureGroup":"hull"},
      {"pressurePSI":0},
      ["n1","n2","n3"],
      {"pressureGroup":""},
],

example of a triangles section with a Group:

"triangles": [
      ["id1:", "id2:", "id3:"],
      {"dragCoef":10},
      {"group":"door_r_st"},
      ["n1","n2","n3"],
      {"group":""},
],

example of a triangles section with {"groundModel":"metal"},:

"triangles": [
      ["id1:", "id2:", "id3:"],
      {"groundModel":"metal"},
      {"dragCoef":10},
      {"group":"door_r_st"},
      ["n1","n2","n3"],
      {"group":""},
],

example of a triangles section with {"triangleType":"NONCOLLIDABLE"}, section:

"triangles": [
      ["id1:", "id2:", "id3:"],
      {"triangleType":"NONCOLLIDABLE"},
      ["n1","n2","n3"],
      {"triangleType":"NORMALTYPE"},
    ],
],

Name	Type	Optional	Default Value	Description
id1	string	required	n/a	Name of the first node
id2	string	required	n/a	Name of the second node
id3	string	required	n/a	Name of the third node
dragCoef	number	optional	10	Drag coefficient of the triangle as a percentage of a flat plate of the same size.
liftCoef	number	optional	dragCoef	Lift coefficient of the triangle as a percentage of a flat plate of the same size. By default this value is equal to dragCoef
stallAngle	number	optional		Defines (in radians) the angle where the lift will begin to stall
groundModel	string	optional	asphalt	Ground model of the triangle. Determines friction behavior. Possible values: asphalt dirt rock metal grass sand rockydirt dirt_grass ice snow mud kickplate --see art/groundmodels.json for more possibilities
pressureGroup	string	optional		Pressure group of the triangle
pressurePSI	number	optional		Sets the pressureGroup pressure in PSI
pressure	number	optional		Sets the pressureGroup pressure in Pascal
breakGroup	string	optional		Used to trigger triangles to break in a group, triggered by any beams in that same group. Broken beams can trigger triangles to break, but broken triangles cannot trigger beams to break.

quads

Quads are meant to simplify the creation of triangles. All parameters from triangles (dragCoef, pressureGroup, etc) are also supported on quads. The way a quad is created, is by creating two triangles. One between node1->node2->node3, and one between node3->node4->node1.

example of a basic quads section:

"quads": [
      ["id1:", "id2:", "id3:", "id4:"],
      {"dragCoef":10},
      {"liftCoef":100},
      ["n1","n2","n3","n4"],
],

Name	Type	Optional	Default Value	Description
id1	string	required	n/a	Name of the first node
id2	string	required	n/a	Name of the second node
id3	string	required	n/a	Name of the third node
id4	string	required	n/a	Name of the fourth node

Quads also share the properties of triangles

Comments in JBeam

1] //
This is for commenting out single lines of JBeam. Example below

            //["f1rr","f1r"],

2] /* */
This is for commenting out blocks of JBeam. The /* begins the comment, and this */ ends the comment. Example below:

            /*
            {"beamSpring":1251000,"beamDamp":250},
            {"beamDeform":16000,"beamStrength":24000},
            ["f1rr","f1r"],
            ["f1r","f1l"],
            ["f1l","f1ll"],
            */

Take note that it isn't allowed to have a disabled section within a disabled section. Although a disabled line within a disabled section is allowed:

            /*
            {"beamSpring":1251000,"beamDamp":250},
            {"beamDeform":16000,"beamStrength":24000},

            /*//THIS IS NOT ALLOWED AND WILL CAUSE ERRORS
            ["f1rr","f1r"],
            ["f1r","f1l"],
            ["f1l","f1ll"],
            */
            */

3] [optional = TRUE]

It is also possible to make beams or triangles 'optional'. This means that if a beam or triangle cannot be generated when the vehicle loads (for ex, if a required node is missing) it doesn't show up with warnings in the console. By hiding intentionally missing beams, it makes it easier to notice an accidental missing beam or triangle if there is a typo or some other problem.

            {"optional":true},
            {"breakGroup":["sunburst_doorhinge_a_FR","sunburst_doorhinge_b_FR","sunburst_fender_a_R"]},
            ["d7r", "fe3r", "fe7r"],
            ["d7r", "d4r", "fe3r"],
            ["d4r", "d1r", "fe3r"],
            ["fe3r", "d1r", "fe1r"],
            {"optional":false},

Tdev (talk) 03:05, 6 February 2016 (CET)

Vehicle Creation

Get started: Introduction to Vehicle Creation

JBeam

Overview	Introduction • Reference • Construction Guide
Physics	Nodes (refNodes) • Beams (Anisotropic • Bounded • Support • Pressured • L-Beam) • Coltris (Quads • Pressure Simulation)
Dynamics	DeformGroups • Engine Thermals • Hydros • Powertrain • PressureWheels • Slidenodes • Slots • Sounds • Superchargers • Turbochargers
Visuals	Flexbodies • Fires • GlowMap • Props (License Plates • Spotlights) • Skins

Extras

Blender Exporter plugin • Modeling and Texturing Guide • Vehicle Materials • Vehicle Specific Bindings

Upkeep

JBeam changelog • 0.8 Mod Conversion Guide • 0.8 Add-on Mod Conversion Guide • 0.8 Configuration Conversion Guide • 0.11 Mod Conversion Guide

Deprecated

HubWheels

See also: JBeam Examples • JBeam Physics Theory