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collisionShape

Holds a set of simple collision volumes (boxes, spheres, cylinders) used by static objects and some animated objects (non-unit) for hit checks, selection and placement.
Not used by units (AnimatedUnit); those rely on other mechanisms.

Overview

  • Purpose: Fast, approximate collisions without per-triangle tests.
  • Where it shows up: Present in StaticObjectCollision and AnimatedObjectCollision models; absent in AnimatedUnit.
  • Engine impact: Cheap broad-phase tests. Triangle trees (e.g. CGeoOBBTree) may be consulted only if needed.

Structure

A compact header plus three counted arrays. There is no “CollisionPrimitive” union; shapes are stored by concrete type.

Field Type Default Description
version byte 1 Format version.
box_count uint – Number of boxes.
boxes BoxShape[box_count] – See BoxShape.
sphere_count uint – Number of spheres.
spheres SphereShape[sphere_count] – See SphereShape.
cylinder_count uint – Number of cylinders.
cylinders CylinderShape[cylinder_count] – See CylinderShape.

BoxShape

Rectangular volume with local transform + AABB extents.

Field Type Description
coord_system CMatCoordinateSystem Local orientation and position (no scale).
geo_aabox CGeoAABox Lower/upper corners in local space.

CGeoAABox

Field Type Description
lower_left_corner Vector3 One corner of the box.
upper_right_corner Vector3 Opposite corner of the box.

SphereShape

Field Type Description
coord_system CMatCoordinateSystem Position (orientation irrelevant).
geo_sphere CGeoSphere Radius + center.

CGeoSphere

Field Type Description
radius float Sphere radius.
center Vector3 Center in local space (often 0,0,0).

CylinderShape

Field Type Description
coord_system CMatCoordinateSystem Local orientation and position.
geo_cylinder CGeoCylinder Center, height, radius.

CGeoCylinder

Field Type Description
center Vector3 Cylinder center in local space.
height float Height along the local up-axis.
radius float Base radius.

Authoring & In-Game Behavior

  • Blender workflow: Create dedicated collision objects (box/sphere/cylinder) and tag them; the exporter writes them into the respective arrays.
  • Transforms: Apply scale/rotation before export. CMatCoordinateSystem stores rotation + position (no non-uniform scale), while dimensions live in the geo structs.
  • Usage pattern: These primitives provide quick acceptance/rejection. If a model also has CGeoOBBTree, detailed triangle tests can follow.

Validation Rules

Rule Why
version == 1 Confirms layout.
Counts match array lengths Prevents read overruns.
Positive dimensions (radius/height/extents) Zero/negative sizes break tests.
Orthonormal rotation in coord_system Keeps boxes/cylinders well-formed.

Performance Notes

  • Spheres are the cheapest test, boxes next, cylinders slightly heavier.
  • Keep the number of shapes minimal; a few well-placed volumes beat many tiny ones.

Cross-References

Known Variants / Game Differences

  • Current data uses the three concrete shape arrays shown above. No union/variant record is present.

Nice to know

The node name is stored as collisionShape (lowercase c) in the hierarchy.