Mouse Modes

The mouse is in one of several modes at any time; the current mouse mode determines the effect of pressing and releasing mouse buttons or the mouse wheel while the mouse is in the graphics window. Each mouse mode, except the lights mode (see below), sets the mouse cursor to a characteristic shape. The mouse mode is selected via the Mouse menu.

The available mouse modes are as follows:

• Rotate Mode (hot key 'r')
  When the mouse is in rotate 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 or right.

  You can leave 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 menu. Also, pressing the rotation hot key r or any of the other mouse mode hot keys causes rotation to stop.

• Translate Mode (hot key 't')
  When the mouse is in translate mode, holding the left button down allows you to move the molecules parallel to the screen plane (left, right, up, and down). To move the molecule towards or away from you, hold the middle button down and move the mouse right or left, respectively.

• Scale Mode (hot key 's')
  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. Scaling can also be accomplished with the mouse wheel (irrespective of the current mode setting) on computers equipped with an appropriate mouse.

• Move Light
  VMD provides four directional lights to illuminate the molecular scene. The lights provide diffuse lighting and specular highlights and help the user perceive surface shape in rendered objects. You can use the mouse to rotate each of the light source directions to a new position. If the light isn't on, moving it will not affect the displayed image. To turn a light on or off, use the Lights item within the Mouse menu.

• Add/Remove Bonds
  When the mouse is in add/remove bonds mode, clicking on atoms in a molecule will add a bond between those atoms if one is not already present, or remove the bond between those atoms if there is already a bond. The two atoms must belong to the same molecule.