LOD

What's a LOD?

LOD means Level of Detail, and is a method of defining, via different variations of a model, how high or low the viewable quality of the model should be, and how it should interact with the environment.

<resolution>

Defines which model to use, depending on several, interdependent in-game conditions (view-distance, number of objects, video quality, CPU utilization, etc.).

This LOD shouldn't contain any empty Named Selections which are used in animations or by the game engine (wheels, etc.), as that might cause the game to crash once the LOD becomes active.

To demonstrate the complexity of the LOD selection, and the effect the resolution name has on LOD switching, a series of tests have been documented here: Resolution LOD Samples

The default Named Property for resolution LOD's is: LodNoShadow=1

Geometry

Defines where the model will collide with other objects.
Should be very simple, and has to fulfill the following criteria in order to work:

• Object must be named ComponentXX (where XX is a consecutive number between 01 and 99).
• Must have 'Mass' (Alt-M).
• Must be closed and convex (Validating Geometries).
• It must be smaller then the size limit.

If the geometry LOD is larger then the size limit, it gets glitchy (collision does not work for example and the object may disappear at certain view angles). The exact value of the limit is not yet known, but it's somewhere around 50-60 meter from the center of origin (meaning that your object can be 100m wide/long at max if it is symmetrical to the center of origin). According to reports there is no limit skywards, so you could make a tower of 200m height. Note that if your object requires a roadway LOD, you need to stay within the roadway size limit, which is smaller.

Geometry objects should have a thickness of at least 0.5 meters in order to work properly.

TIP: Oxygen2/Objectbuilder can do ComponentXX naming automatically. [Structures->Topology->Find Components]

Arma 3:

• Geometry LOD is used for Collision if one of the colliding Objects is not a PhysX simulated Object. For example living Soldiers are not PhysX objects. Tank-Soldier Collision is therefore determined by Geometry LOD, even-though the Tank is a PhysX simulated Object.
• For PhysX Objects the Mass value and the Mass distribution is critically important for the Objects physical behavior [Keywords: "Inertia" and "Moment of Inertia" ]

• The default Named Properties for the Geometry LOD are: canocclude=0 and canbeoccluded=1 (for Vehicles, Characters and Weapons)

Geometry Phys

Arma 3 only

Defines the collision model that is used in a collision between two PhysX Objects.

The same criteria like for the Geometry LOD apply. The difference is that Geometry Phys does not contain Mass information. For helicopters, do not use 'Find Components' on all parts as this will make rotor blades cause critical failure. Cut the blades and any non critical structures before using find components, then paste them back in.

NOTE: Requires Objectbuilder to be selectable in the LOD list

NOTE: Grenades are currently PhysX objects, that means they do use this LOD instead of Fire Geometry.

Fire Geometry

Defines where the model will collide with bullets & rockets. If this LOD is not present the Geometry LOD will be used instead. Should be simplified as much as possible, but can be a bit more complex then Geometry or Geometry Phys

• Must be closed and convex (Validating Geometries).
  

Proxies for the driver & passenger must be present into this LOD as well (they can be copied from the Resolution LOD). Otherwise the units will be invincible. One should also do any geometry validation before adding the proxies, otherwise they will not be functional.

Arma 3:

All Components should have a damage material applied. This defined the penetrability of the object and the impact effect type. There are two possibilities for Materials: Normal Materials or Plate Materials.

• Plate Materials have a pre-defined thickness. It doesnt matter how thick the modelled component in the Fire Geometry is.
• Normal Materials only define material characteristics. The thickness is determined by the modelled component.

Example: A component representing a Wall with a thickness of 2m is modelled in the Fire Geometry. If we apply concrete.rvmat it will behave like a 2m thick concrete wall. If we apply concrete_plate.rvmat, it will behave like a 30mm thick concrete wall.

NOTES:

• If no materials are applied, Arma 3 will default to a nonpenetrable material with dirt impact effect type
• If during binarization, the P: drive is not properly set up the referenced materials won't be found -> default to dirt impact type
• Arma 3 has many materials that can be used directly or as base for custom materials, they can be found in "...\arma3\addons\data_f.pbo\penetration\"
• Arma 3 Plate materials are usually 30mm thick. Armour plate materials are the only ones with different thicknesses.

For more details on how Damage&Penetration interact see Arma 3 Damage Description

Hit-points

Hit-pointLODs define, via unconnected named vertexes, where certain destroyable parts of a model are (e.g. wheels, lights, etc.).

NOTE: The spacing between the points needs to be tuned in close correlation with the Hitpoint Config Class in the Objects Config and the Fire Geometry

For more details on how Damage&Penetration interact see Arma 3 Damage Description

Memory

Named Selections that are used to define lights, vehicle entry points, etc., as well as control points for Animations.

TIP: For memorypoint creation in an external modelling tool that has no OFP/Arma export plugin, you can create a triangle in the external modeller. Place one or two vertices of the triangle where you need them. Import the triangle(s) into Oxygen2/Objectbuilder. Delete the obsolete point(s) of the triangle.

Paths

On models that will be navigated by AI units (e.g. buildings), the paths have to be defined with this LOD.

Roadway

If a units is supposed to be able to stand on top of a model, that surface has to be defined by a RoadwayLOD.

Make sure that a RoadwayLOD doesn't overlap with a GeometryLOD, or the unit will start to wobble at those points.

The roadway LOD does not work if components are further away from the center of origin then 36 meter. Therefore you can make 72m long bridges at most. If that is not sufficient for your object then you need to split your model into multiple smaller segments with a seperate .p3d modelfile each.

LandContact

Where the object touches the ground. (Defined by a single vertex per contact point.)

ViewGeometry

The visible geometry of the model.

As an example: If you have an object with this LOD properly configured, you will not be able to spot other units through the model. AI will not be able to spot other units through the model.

View - Cargo

What a cargo passenger can see of the model.

In vehicles of the class "Car", the player will always see this view, whether he's the driver, co-driver or cargo. (Unless the "View - Pilot" is defined. Then that view is taken for any position inside the vehicle.)

View - Commander

What the commander can see of the model.

In vehicles, this will be the commander's first person view of the model.

View - Gunner

What the gunner can see of the model.

In vehicles, this will be the gunner's first person view of the model.

View - Pilot

What the pilot/driver can see of the model.

In vehicles of the class "Car", the player will always see this view, whether he's the driver, co-driver or cargo. Players position in the LOD is determined by his proxy position.

ShadowVolume

ArmA/OFPE only: Visible shadow resolution lod for model. Typically named ShadowVolume 0.000 (Few features) and ShadowVolume 0.100 (same amount of features as the main visual model (i.e. equipment, weapon systems, etc). Structure within it must be Triangulated and have Sharp edges. (Also see this article)