Mouse Modes

The mouse, while positioned within the graphics display window, is used to perform a variety of functions. There are several different modes which the mouse may be in at any time; the current mouse mode determines what the effect is when the user presses the left or middle button. Each mouse mode, except the lights mode (see below), causes the cursor to acquire a characteristic shape. The mouse mode is changed via the Mouse Form.

The available modes are as follows:

• Mouse Mode $\rightarrow$ Rotation Mode
  When the mouse is in this mode, holding the left mouse button down and moving the mouse rotates the molecules about axes parallel to the screen, in a `virtual trackball' behavior. To get a rotation around the axes coming out of the screen (the `z' axis), hold the middle button down and move the mouse left (clockwise) or right (counter-clockwise).

  You can keep the molecules rotating without continuously moving the mouse. Start the molecule moving with the mouse, as above, then release the mouse button before you stop moving the mouse. With some practice it becomes easy to impart a slight spin on the molecule, or whirl it about madly. To stop the rotation, either press and hold the left mouse button down until the molecule stops moving, or select `Stop Rotation' in the Mouse form.

  The hot key to enter rotation mode is r. Also, pressing r or any of the other mouse mode hot keys causes the rotation to stop.

• Mouse Mode $\rightarrow$ Translation Mode
  When the mouse is in translation mode, holding the left button down allows you to move the molecules parallel to the screen plane, so, for example, moving the mouse left moves the system left. To move the molecule towards or away from you, hold the middle button down and move the mouse right or left, respectively.

  The translation hot key is t; pressing t while the mouse is in the graphics display window will change the mouse to translation mode.

• Mouse Mode $\rightarrow$ Scaling Mode
  The scaling mode has the simplest mouse controls as pressing either the left or middle button down and moving to the right enlarges the molecules, and moving the mouse left shrinks them. The difference is that the middle button scales faster than the left button.

  The scaling hot key is s.

• Mouse Mode $\rightarrow$ Move Lights Mode
  VMD provides up to four separate light sources to illuminate the graphics objects in the display window. These light sources act independently, and use the native lighting hardware acceleration available on the graphics workstation (if any). Thus, they do not cast shadows, and their effect is not calculated with any form of raytracing or similar algorithm. They do, however, add a nice realistic effect to the objects and help give the appearance of material characteristics to spheres, cylinders, and so forth. You can use the mouse to rotate each of the light sources in space to a new position; you can even set a specific light to rotate continuously about the origin. The light sources are located at infinity, so only their orientation is important. If the light is not currently on, moving that light source will not affect any change in the displayed image. To turn a light on or off, use the Lights browser in the upper right of the Display form.