对于一个系统全局属性有：

• 质量(mass)

• 质心(mass center)

• 惯性张量(matrix of inertia)

• 关于一个轴的矩(moment about an axis)

• 关于一个轴的惯性半径(radius of gyration about an axis)

• 惯性的主属性，比如主轴(principal axis)，主矩(principal moments)和主惯性半径(principal radius of gyration)

在Open CASCADE Technology (OCCT)中，全局属性（如尺寸、质量、质心、惯性矩等）的计算是通过BRepGProp库来实现的。这个库提供了函数来计算几何形状的各种属性。

#include <TopoDS.hxx>
#include <BRepPrimAPI_MakeBox.hxx>
#include <GProp_GProps.hxx>  
#include <BRepGProp.hxx> 
#include <GProp_PrincipalProps.hxx> 

#include"Viewer.h"

int main(int argc, char* argv[])
{
    TopoDS_Shape box = BRepPrimAPI_MakeBox(1,2,3);
    GProp_GProps System;
    BRepGProp::LinearProperties(box, System);
    BRepGProp::SurfaceProperties(box, System);
    BRepGProp::VolumeProperties(box, System);
    BRepGProp::VolumeProperties(box, System);
    double out=System.Mass();
    gp_Pnt G = System.CentreOfMass();
    GProp_PrincipalProps Pp = System.PrincipalProperties();
    double Ixx=0, Iyy=0, Izz=0, Rxx=0, Ryy=0, Rzz=0;
    Pp.Moments (Ixx, Iyy, Izz);
    Pp.RadiusOfGyration (Ixx, Iyy, Izz);
    std::cout <<"volume=" << out << std::endl;
    std::cout << "CentreOfMass=(" << G.X()<<","<<G.Y()<<","<<G.Z() << ")" << std::endl;
    std::cout << "Ixx=" << Ixx << std::endl;
    std::cout << "Iyy=" << Iyy << std::endl;
    std::cout << "Izz=" << Izz << std::endl;
    std::cout << "Rxx=" << Rxx << std::endl;
    std::cout << "Ryy=" << Ryy << std::endl;
    std::cout << "Rzz=" << Rzz << std::endl;
    Viewer vout(50, 50, 500, 500);
    vout << box;
    vout.StartMessageLoop();
    return 0;
}

volume=6

CentreOfMass=(0.5,1,1.5)

Ixx=1.04083

Iyy=0.912871

Izz=0.645497

Rxx=0

Ryy=0

Rzz=0