
	3D Viewers

To pan the view about, move the mouse pointer so it's inside the viewer area, hold down the middle mouse button, and then move the mouse about. (NOTE: Users with two button mice should use the right mouse button instead of the missing middle button.)

To zoom in and out, make sure the mouse pointer is inside the viewer area again, hold down the <Ctrl> key and the middle mouse button, and move the mouse up and down. Alternatively, hold down both the left and middle mouse buttons, and move the mouse left and right to zoom; this is a similar action to that used in Maya for view zooming.

Figure 370. 3D Viewer Controls

To rotate the view around the center of the viewing area, hold down the left mouse button and move the mouse about. To spin the view around, hold down the <Ctrl> key and the left mouse button, and move the mouse from side to side (see Figure 370).

For finer control over the pan, zoom, rotate or spin, hold down the <Tab> key while you are doing the keyboard and mouse actions described above.

There are also a small number of common keyboard short cuts. Type them in when the mouse pointer is inside the viewing area.

<s> key: Shade any surfaces.

<o> key: Toggle orthographic/perspective projection.

<p> key: Save the current viewing parameters. Usually these will be loaded up as the initial view the next time you start the viewer.

<5> keypad, or <Home>: Center the view.

<5> keypad, or <Home>, with <Space> key depressed: Reset the view.

<4> keypad: Rotate the view 30 degrees to the left.

<6> keypad: Rotate the view 30 degrees to the right.

<8> keypad: Rotate the view 30 degrees up.

<2> keypad: Rotate the view 30 degrees down.

<PrintScreen> key: Save the displayed image into "snap.rgb" (SGI IRIX), or "snap.bmp" (Windows NT).

<Esc> or <q> key: Quit from the program.

Setting Your "Up"

By default, the 3D scene is viewed Z-up. This is the convention among professions that have traditionally worked off of a 2D plan, defined by X and Y coordinates, that is then extruded up in Z to make the 3D object. This group includes engineers, product designers and architects.

But if you sit back and sketch an object out on a computer screen, its up corresponds to the screen's vertical Y axis. For this reason many computer graphics programmers, and the software they develop, have adopted a Y-up convention.

You can switch between X-up, Y-up and Z-up at any time by typing one of the <x>, <y> or <z> keys.

You can also define any arbitrary vector as your up axis by first setting the view so your up is going up the screen, then hold down the <Ctrl> key and click the left mouse button. To reset the view back to the default of Z-up, hold down <Space>, then hit <5> on the key pad or <Home>.