PHYS

.phys files are chunked. The files are used by Blizzard's Domino physics engine which got added to WoW in the fourth expansion (MoP). In build 15464, there is one .phys file "item/objectcomponents/waist/buckle_panstart_a_01.phys". .phys files are an extension to M2s. The M2 requests a .phys file to be loaded by having GlobalModelFlags & 0x20 set.

The main PHYS chunk is followed by an unordered sequence of unique chunks of the other types.

// vec*: * floats
// mat*x*: * times * floats.

• 1 phys
• n body
  • n shapes
    • 1 box
    • 1 capsule
    • 1 sphere
    • 1 (tree mesh [*])
    • 1 (height field [*])
• n joints
  • 1 weld
  • 1 spherical
  • 1 shoulder
  • 1 (mouse [*])
  • 1 (distance [*])
  • 1 (revolute [*])

[*] supported by domino, but not available in wow

One body is connected to one bone. Bodies are connected via joints. A joint is of type weld, spherical or shoulder. A body is constructed out of shapes. A shape is a box, capsule or sphere.

PHYS

 short must_be_null; // PhysData::Load fails otherwise. (if (phys->token != 'PHYS' || phys->must_be_null) return false;)

BODY

struct BODYEntry
{
  unsigned short type; // maps to dmBodyDef type enum. 0 -> 1, 1 -> 0 = dm_dynamicBody, * -> 2. Only one should be of type 0 (root). possibly only 0 and 1.
  char PADDING_a[2];
  vec3 position;
  unsigned short modelBoneIndex;
  char PADDING_b[2];
  int shapes_base; // starting at shapes[shapes_base]
  int shapes_count; // shapes_count shapes are in this body.
} bodies[];

SHAP

struct SHAPEntry
{
  short shapeType; // 0 -> box, 1 -> capsule, 2 -> sphere
  short shapeIndex; // into the corresponding chunk
  char unk[4];
  float friction;
  float restitution;
  float density;
} shapes[];

BOXS

struct BOXSEntry
{
  mat3x3 a;
  vec3 b;
  vec3 c;
} boxShapes[];

CAPS

struct CAPSEntry
{
  vec3 localPosition1;
  vec3 localPosition2;
  float radius;
} capsuleShapes[];

SPHS

struct SPHSEntry
{
  vec3 localPosition;
  float radius;
} sphereShapes[];

JOIN

struct JOINEntry
{
  unsigned int bodyAIdx;
  unsigned int bodyBIdx;
  char unk[4];
  short jointType; // 0 == sphericalJoint, 1 == shoulderJoint, 2 == weldJoint
  short jointId; // reference into the corresponding chunk entries.
} joints[];

WELJ

struct WELJEntry
{
  mat3x4 frameA;
  mat3x4 frameB;
  float frequency;
  float dampingRatio;
} weldJoints[];

SPHJ

struct SPHJEntry
{
  vec3 anchorA;
  vec3 anchorB;
  float frictionTorque;
} sphericalJointEntries[];

SHOJ

struct SHOJEntry
{
  mat3x4 frameA;
  mat3x4 frameB;
  float lowerTwistAngle;
  float upperTwistAngle;
  float coneAngle;
} shoulderJoints[];