Internal type codes for debugging¶

Use these tables when inspecting contact arrays, owner state, or debugger output. The source of truth is src/DEM/Defines.h; storage types are defined in src/DEM/VariableTypes.h. Values describe this checkout and should not be assumed identical in older releases. Prefer symbolic constants in application code.

Contact types¶

contact_t is an unsigned 8-bit integer. These codes appear in contactTypePrimitive and contactTypePatch. They describe the geometry pair, not the owner IDs or the position of a contact in an array.

Decimal	Hex	Internal name	Geometry A	Geometry B
0	0x00	`NOT_A_CONTACT`	None	None
17	0x11	`SPHERE_SPHERE_CONTACT`	Sphere	Sphere
18	0x12	`SPHERE_TRIANGLE_CONTACT`	Sphere	Triangle
20	0x14	`SPHERE_ANALYTICAL_CONTACT`	Sphere	Analytical component
34	0x22	`TRIANGLE_TRIANGLE_CONTACT`	Triangle	Triangle
36	0x24	`TRIANGLE_ANALYTICAL_CONTACT`	Triangle	Analytical component

SPHERE_MESH_CONTACT is a legacy alias for SPHERE_TRIANGLE_CONTACT (value 18), not an additional contact type. NUM_SUPPORTED_CONTACT_TYPES is 5: it is a count, not the maximum code. ALL_CONTACT_TYPES lists the five supported pairs; isSupportedContactType validates a code.

Encoding and decoding¶

The high four bits hold geometry A’s type, and the low four bits hold geometry B’s type:

contact_code = (geometry_A << 4) | geometry_B
geometry_A = contact_code >> 4
geometry_B = contact_code & 0x0F

For example, 36 is 0x24: triangle (2) against analytical component (4). Order matters: 0x21 is not a supported substitute for 0x12. Packing two geometry codes does not by itself make the resulting pair supported.

The C++ helpers are encodeType, decodeTypeA, and decodeTypeB. Their packing width depends on the template argument types. When decoding an integer from a log, cast it to deme::contact_t first so the helpers use four-bit fields rather than fields sized for int:

const auto type = static_cast<deme::contact_t>(36);
const auto type_a = deme::decodeTypeA(type);  // GEO_T_TRIANGLE
const auto type_b = deme::decodeTypeB(type);  // GEO_T_ANALYTICAL

Geometry and owner codes¶

geoType_t and ownerType_t are unsigned 8-bit integers. A geometry is a collision component belonging to an owner; a clump can contain many spheres, and a mesh can contain many triangles.

Value	Geometry code	Internal owner code	Meaning
0	`NOT_A_GEO`	`NOT_A_OWNER`	No geometry / no owner type
1	`GEO_T_SPHERE`	`OWNER_T_CLUMP`	Sphere component / clump owner
2	`GEO_T_TRIANGLE`	`OWNER_T_MESH`	Triangle component / mesh owner
4	`GEO_T_ANALYTICAL`	`OWNER_T_ANALYTICAL`	Analytical component / analytical owner

The analytical code is 4, not 3; these values also participate in bitwise operations. ownerTypes stores the internal owner codes. Combined owners have no separate OWNER_T_COMBINED code: rigid grouping does not introduce a fourth geometry or owner type. See Core concepts for owners and members.

Do not confuse these codes with `OWNER_TYPE`¶

The separate C++ enum class OWNER_TYPE, also exposed in Python, has the following underlying values. It is not numerically interchangeable with the internal OWNER_T_* constants:

Enum	Enum value	Corresponding internal code	Internal value
`OWNER_TYPE::CLUMP`	0	`OWNER_T_CLUMP`	1
`OWNER_TYPE::ANALYTICAL`	1	`OWNER_T_ANALYTICAL`	4
`OWNER_TYPE::MESH`	2	`OWNER_T_MESH`	2

For Python enum access, use deme.OWNER_TYPE.CLUMP and the analogous names. Check the field or API’s declared type before interpreting a numeric value.

Analytical geometry subtypes¶

objType_t is an unsigned 8-bit integer identifying the shape of an analytical component. All these shapes have geometry code GEO_T_ANALYTICAL (4); their subtype is not packed into the contact code.

Value	Internal name	Shape
0	`ANAL_OBJ_TYPE_PLANE`	Plane
1	`ANAL_OBJ_TYPE_PLATE`	Plate
2	`ANAL_OBJ_TYPE_CYL_INF`	Infinite cylinder
3	`ANAL_OBJ_TYPE_CONE_INF`	Infinite cone
4	`ANAL_OBJ_TYPE_CONE`	Finite cone

This table lists declared subtype codes; it does not assert that every shape supports every contact path. In particular, subtype 0 means a plane, not an invalid geometry. The separate normal-direction flag uses ENTITY_NORMAL_INWARD = 0 and ENTITY_NORMAL_OUTWARD = 1.

Reading IDs and debugger output¶

Type codes are distinct from owner IDs, geometry IDs, and family numbers. An owner ID of 0 may be valid even though the owner type code 0 is a sentinel.
Primitive and patch contacts use the same contact type encoding but different geometry indexing. DEME_GET_GEO_OWNER_ID maps triangles through ownerTriMesh; DEME_GET_PATCH_OWNER_ID maps mesh patches through ownerPatchMesh. Do not use a mesh patch index as a triangle index.
Unsigned 8-bit values may print as characters in C++ streams. Cast a type code to unsigned int when printing its numeric value.