affine3d affine2d一个demo

#include <Eigen/Dense>#include <iostream>#include <string>int main(){    using namespace Eigen;    using namespace std;    Vector3d p3d(1.,2.,3.);    cout << p3d << endl << endl;    Affine3d S3d = Translation3d(2.,2.,2.)*Scaling(3.,2.,5.);    Vector3d scalled = S3d*p3d;    cout << S3d.matrix() << endl << endl;    cout << scalled << endl << endl;    cout << string(16,'_') << endl;    Vector2d p2d = p3d.topRows<2>();    cout << p2d << endl << endl;    Affine2d S2d = Translation2d(S3d.translation().topRows<2>()) *                   S3d.linear().topLeftCorner<2,2>();    Vector2d scalled2d = S2d*p2d;    cout << S2d.matrix() << endl << endl;    cout << scalled2d << endl << endl;}

Output:

1233 0 0 20 2 0 20 0 5 20 0 0 15617________________123 0 20 2 20 0 156