Vec3D

The class Vec3D represents three-dimensional vectors and many useful operations. The operators allow you to use expressions such as

0.3*(a-b)*(c+d)
Code:
Vec3D.h
Vec3D.cpp

Public Methods

constructors

Vec3D();
Vec3D(double fX, double fY, double fZ);
Vec3D(const Vec3D *pv);
Vec3D(const Vec3D &v);

Apart from the empty constructor, you can create Vec3D objects by passing the components, or use a copy constructor

set

void set(double fX, double fY, double fZ);
void set(const Vec3D *pv);
void set(const Vec3D &v);

Change the vector’s components,

addition

void add(const Vec3D *pv);
void add(const Vec3D &v);
Vec3D &operator+=(const Vec3D &v);
Vec3D operator+(const Vec3D &v1,  const Vec3D &v2);

Both add() functions, as well as the operator+=, change the values of this. The operator+ returns a new vector.

subtraction

void subtract(const Vec3D *pv);
void subtract(const Vec3D &v);
Vec3D &operator-=(const Vec3D &v);
Vec3D operator-(const Vec3D &v1,  const Vec3D &v2);

Both subtract() functions, as well as the operator-=, change the values of this. The operator- returns a new vector.

scale

void scale(double f);
Vec3D &operator*=(const double f);
double calcNorm() const;

scalar product (dot)

inline double dotProduct(const Vec3D *pv);
inline double dotProduct(const Vec3D &v);
Vec3D operator*(const Vec3D &v1,  double f);
Vec3D operator*(double f, const Vec3D &v1);

Both dotProduct() functions change he values of this. The two operator*() create a new vector.

vector product (cross)

Vec3D *crossProduct(const Vec3D *pv);
Vec3D operator*(const Vec3D &v1,  const Vec3D &v2);

The methods crossProduct() allocates space for the result which must be deleted by the user.

Length and Distance

double dist(const Vec3D *pv);
double dist(const Vec3D &v);
void normalize();

The dist() functions return the distance from this to the pv (or v)

The method normalize() scales the vector to unit length.

Other

double getCrossSize(const Vec3D *pv) const;
double getCrossSize(const Vec3D &v) const;
double getAngle(const Vec3D *pv) const;
double getAngle(const Vec3D &v) const;
bool operator==(const Vec3D &v) const;
getCrossSize() returns the length of the cross product.
getAngle() returns the angle between this and and the argument in radians.
operator==() is a “fuzzy” equality: it returns true if the components differ less than a certain amount.

Example

Compile with

g++ vec_example.cpp Vec3D.cpp -o vec_example

Code for vec_example:

#include <cstdio>
#include "Vec3D.h"

void showVec(Vec3D *pv, const char *pCaption) {
    printf("%s: (%f, %f, %f)\n", pCaption, pv->m_fX, pv->m_fY, pv->m_fZ);
}

void showVec(const Vec3D &v, const char *pCaption) {
    printf("%s: (%f, %f, %f)\n", pCaption, v.m_fX, v.m_fY, v.m_fZ);
}

int main(int iArgC, char *apArgV[])  {

     Vec3D v1(1,3,6);
     showVec(v1, "v1");
     Vec3D v2{2,5,8};
     showVec(v2,"v2");

     Vec3D v3 = v1 + v2;
     showVec(v3, "v3");

     printf("length(vr): %f\n", v3.calcNorm());
     v3.normalize();
     showVec(v3, "v3 normalized");

     Vec3D x(1, 0, 0);
     Vec3D y(0, 1, 0);
     Vec3D z(0, 0, 1);
     showVec(x,"x");
     showVec(y,"y");
     showVec(z,"z");
     Vec3D xy = x * y;
     showVec(xy, "x * y");
     if (z == xy) {
         printf("x * y is indeed z\n");
     } else {
         printf("something is wrong...\n");
     }

     Vec3D v = 0.3*(v2-v1)*(v3+x);
     showVec(v, "0.3*(v2-v1)*(v3+x)");

     showVec(v3.calcNorm()*(v1+v2-v3)*(x+y), "v3.calcNorm()*(v1+v2-v3)*(x+y) (direct)");

     return 0;
}