The Gearbox model tag contains the marker points and render models for objects such as vehicles, scenery, and weapons among others. It is not collideable nor animated on its own, and objects may reference additional model_
Don't confuse this tag with the Xbox-only model. Gearbox Software created this tag class for the PC port, and it is therefore used in all derivatives of that port, like Mac, Demo, and MCC. Unlike model, this tag uses uncompressed vertices.
Each part of a model can reference a different shader, like the Warthog's windscreen using a shader_
Nodes can be thought of as the model's "skeleton" and can be animated to move parts of the model. Each vertex can be influenced by up to 2 nodes. H1A and H1CE 1.10 allow up to 63 model nodes. Older versions of H1CE and H1X allow 48.
Markers are simple named points with orientation attached to a model. Since they are parented by nodes, they can be animated. Markers can be used for a variety of purposes, such as attaching objects together with scripts (e.g. Pelicans carrying Warthogs), attaching widgets like antenna, or firing projectiles from in the case of weapons.
This tag only contains the marker data but other tags usually determine how they are used. However, certain marker names have special behaviour in-engine:
- Determines where AI look at when scripted to talk to another character.
- Base location for the friendly indicator in multiplayer.
- Used as a ray origin when testing if AI can see their enemy.
primary trigger: Where a weapon's primary trigger projectiles and effects come from. See also the projectiles use weapon origin field.
secondary trigger: As above, for secondary triggers (second trigger slot).
front: Possibly used to used to see if you're facing a device_
control, if present.
ground point: Determines the resting point for items.
left hand: Used during the grenade throwing animation.
melee: Where melee damage comes from here. If not present, the engine picks an unknown default location.
- When used on a vehicle with "alien scout" or "alien fighter" vehicle physics type, creates a dust cloud effect when the vehicle is hovering close to the ground. This can be seen at a piloted Banshee's wingtips when sitting on the ground.
- When the vehicle physics type is "human plane", creates a similar dust effect if the marker is pointed at nearby ground. Used for the Pelican's thrusters.
jet thrusters: Can also be used for vehicles with "human plane" physics to create the Pelican's thruster dust effect.
Tool only includes markers from the
Regions are named sections of the model which can have multiple permutations. Region names are used by the engine to relate parts of the render model with the collision model. For example, a Flood combat form losing an arm. Some regions have special behaviour in-engine:
head: Sets headshot areas for damage_
Regions render in the order they are stored in the tag. When naming regions, consider that they will be sorted by name when compiled into the
.gbxmodel. This can be important for skyboxes and objects with multiple layers of alpha-blended transparent shaders which aren't z-culled and need a correct sorting order to be explicitly defined, assuming the object is viewed mostly from one direction.
A permutation is a variation of a region that can be randomly selected. They are often used to give bipeds visual variety. Some permutations have special behaviour in-engine:
~blur: Switched to depending on weapon rate of fire and vehicle speed to fake motion blur. Used for the Warthog tires and chaingun when spinning fast enough.
~damaged: Switched to depending how much damage the object takes based on Damage Threshold
Permutations can also be set via script or the Desired Permutation field when placing objects in a Scenario. In order to use the Desired Permutation field the model's permutations must be named in a specific way:
Randomly selected permutations are not network synchronized.
Level of detail
Models can contain multiple levels of detail (LODs), ranging from simplified meshes with reduced shader count to high detail meshes with numerous complex shaders. The game will select a LOD based on the on-screen diameter of the object's bounding sphere in pixels and this tag's LOD cutoffs. Objects which are very distant or small don't need a lot of geometric detail, so they can be rendered using low quality LODs to keep the framerate high in busy scenes.
Halo CE supports 5 LODs. From best to worst quality:
- super high
- super low
When rendering first person models, Halo always uses the lowest quality LOD instead of the highest. When creating FP arms or weapons create a separate FP model from your 3P model which only includes a single super high LOD.
LODs are created by using a special naming convention when compiling models with Tool.
If enabled, all model markers will be rendered in 3D with their name and rotation axis.
If enabled, all model skeletons will be rendered. Nodes are shown as axis gizmos and connected to their parents by white lines.
Structure and fields
|node list checksum|
|super high detail cutoff|
|high detail cutoff|
|medium detail cutoff|
|low detail cutoff|
|super low detail cutoff|
|super low detail node count|
|low detail node count|
|medium detail node count|
|high detail node count|
|super high detail node count|
|base map u scale|
|base map v scale|
Generated in postprocessing from the markers in the model's permutations.
Thanks to the following individuals for their research or contributions to this topic:
- Fubih (Regions render order tip)
- gbMichelle (Node limits)
- Kavawuvi (Invader tag definitions)
- MosesOfEgypt (Tag structure research)