Shifting

The function shift() adds its arguments to the corresponding world_coordinates of a Point. In the following example, the function show() is used to print the world_coordinates of p0 to standard output.

     Point p0(0, 0, 0);
     p0.shift(1, 2, 3);
     p0.show("p0:");
     -| p0: (1, 2, 3)
     p0.shift(10);
     p0.show("p0:");
     -| p0: (11, 2, 3)
     p0.shift(0, 20);
     p0.show("p0:");
     -| p0: (11, 22, 3)
     p0.shift(0, 0, 30);
     p0.show("p0:");
     -| p0: (11, 22, 33)
     

shift takes three real arguments, whereby the second and third are optional. To shift a Point in the direction of the positive or negative y-axis, and/or the positive or negative z-axis only, then a 0 argument for the x direction, and possibly one for the y direction must be used as placeholders, as in the example above.

shift() can be invoked with a Point argument instead of real arguments. In this case, the x, y, and z-coordinates of the argument are used for shifting the Point:

     Point a(10, 10, 10);
     Point b(1, 2, 3);
     a.shift(b);
     a.show("a:")
     -| a: (11, 12, 13)
     

Another way of shifting Points is to use the binary += operator (Point::operator+=()) with a Point argument.

     Point a0(1, 1, 1);
     Point a1(2, 2, 2);
     a0 += a1;
     a0.show("a0:");
     -| a0: (3, 3, 3)