you can use Camerapick with the mouse coords to select something. The Mesh must be pickable (see entitypickmode).
positioning in 3d is about the same as in 2D, tho with one more dimension. There are diffrent ways to define the third dimension. It is also up to your design to define what's the third dimension at all, depth or height or width.
you could use mouseX and -Y for X and y and the mousewheel for Z.
you could position a plane at these coordinates, an insisible one (entitalpha zero) that is pickable. after selecting a spaceship you turn all ships pickmodes off, then use the plane to determine the current picked location and position the spaceship right there. This will look as if you move the spaceship with the mouse, plus the mousewheel would move it away in Z-direction.
But as I said, there are many ways, and maybe you'll come up with something absolutely new and amazing.
positioning in 3d is about the same as in 2D, tho with one more dimension. There are diffrent ways to define the third dimension. It is also up to your design to define what's the third dimension at all, depth or height or width.
you could use mouseX and -Y for X and y and the mousewheel for Z.
you could position a plane at these coordinates, an insisible one (entitalpha zero) that is pickable. after selecting a spaceship you turn all ships pickmodes off, then use the plane to determine the current picked location and position the spaceship right there. This will look as if you move the spaceship with the mouse, plus the mousewheel would move it away in Z-direction.
But as I said, there are many ways, and maybe you'll come up with something absolutely new and amazing.