Defined in include/extensions/PxMassProperties.h

class PxMassProperties

Utility class to compute and manipulate mass and inertia tensor properties.

In most cases PxRigidBodyExt::updateMassAndInertia(), PxRigidBodyExt::setMassAndUpdateInertia() should be enough to setup the mass properties of a rigid body. This utility class targets users that need to customize the mass properties computation.

Public Functions

inline PxMassProperties()

Default constructor.

inline PxMassProperties(const PxReal m, const PxMat33 &inertiaT, const PxVec3 &com)

Construct from individual elements.

inline PxMassProperties(const PxGeometry &geometry)

Compute mass properties based on a provided geometry structure.

This constructor assumes the geometry has a density of 1. Mass and inertia tensor scale linearly with density.


geometry[in] The geometry to compute the mass properties for. Supported geometry types are: sphere, box, capsule and convex mesh.

inline PxMassProperties operator*(const PxReal scale) const

Scale mass properties.


scale[in] The linear scaling factor to apply to the mass properties.


The scaled mass properties.

inline void translate(const PxVec3 &t)

Translate the center of mass by a given vector and adjust the inertia tensor accordingly.


t[in] The translation vector for the center of mass.

Public Members

PxMat33 inertiaTensor

The inertia tensor of the object.

PxVec3 centerOfMass

The center of mass of the object.

PxReal mass

The mass of the object.

Public Static Functions

static inline PxVec3 getMassSpaceInertia(const PxMat33 &inertia, PxQuat &massFrame)

Get the entries of the diagonalized inertia tensor and the corresponding reference rotation.

  • inertia[in] The inertia tensor to diagonalize.

  • massFrame[out] The frame the diagonalized tensor refers to.


The entries of the diagonalized inertia tensor.

static inline PxMat33 translateInertia(const PxMat33 &inertia, const PxReal mass, const PxVec3 &t)

Translate an inertia tensor using the parallel axis theorem.

  • inertia[in] The inertia tensor to translate.

  • mass[in] The mass of the object.

  • t[in] The relative frame to translate the inertia tensor to.


The translated inertia tensor.

static inline PxMat33 rotateInertia(const PxMat33 &inertia, const PxQuat &q)

Rotate an inertia tensor around the center of mass.

  • inertia[in] The inertia tensor to rotate.

  • q[in] The rotation from the new to the old coordinate frame, i.e. q.rotate(v) transforms the coordinates of vector v from the old to the new coordinate frame.


The rotated inertia tensor.

static inline PxMat33 scaleInertia(const PxMat33 &inertia, const PxQuat &scaleRotation, const PxVec3 &scale)

Non-uniform scaling of the inertia tensor.

  • inertia[in] The inertia tensor to scale.

  • scaleRotation[in] The rotation from the scaling frame to the frame that inertia is expressed in. I.e. scaleRotation.rotate(v) transforms the coordinates of vertex v from inertia’s frame to the scaling-axes frame.

  • scale[in] The scaling factor for each axis (relative to the frame specified with scaleRotation).


The scaled inertia tensor.

static inline PxMassProperties sum(const PxMassProperties *props, const PxTransform *transforms, const PxU32 count)

Sum up individual mass properties.

  • props[in] Array of mass properties to sum up.

  • transforms[in] Reference transforms for each mass properties entry.

  • count[in] The number of mass properties to sum up.


The summed up mass properties.