![[IViPP's Initial Clipping Plane Panel]](figures/figure_4_1.png)
Figure 4.1. IViPP’s initial clipping plane panel.
The display can be rotated around the origin by using the mouse. Click the mouse’s left button, and drag the cursor to pivot around the origin of IViPP’s axes.
To translate the display, click and drag with the right mouse button.
Alternatively, you can use the arrow keys on your keyboard to translate the display.
Zooming in or out is done with the plus and minus keys on the keyboard, respectively. Holding the Shift key while zooming will increase the amount that is zoomed at each step, giving you faster zooming to approximately the level you want. You can also use the scroll wheel on your mouse (if it has a scroll wheel) to zoom.
Pressing the r key will reset the view to the way it was when the file was first opened. Rotation, translation, and zoom will all be set to their default values.
“Clipping planes” remove certain objects from view; the metaphor is a plane passing through the displayed particles and geometry, such that only things on one side of the plane are visible. Users define a clipping plane by the orientation of its normal vector, and its distance from the origin in the normal direction. The visible side of the clipping plane is the side to which the normal points.
To use clipping planes, select “Clipping Planes” from IViPP’s “View” menu. This makes a clipping plane panel visible, as shown in Figure 4.1.
To create a clipping plane, click on the small page icon in the upper left part of the clipping pane panel. This adds a clipping pane description to the panel, as shown in Figure 4.2
![[A Clipping Plane Specification]](figures/figure_4_2.png)
There are 3 main parameters to specify for clipping planes. “Altitude” is the angle, in degrees, of the normal vector above the XZ plane.
“Azimuth” is the normal’s angle clockwise (as seen from the positive Y axis) from the positive X axis. “Distance” is the distance from the origin to the plane in the direction of the plane’s normal vector. You can define these parameters by either typing in the corresponding text boxes, or adjusting the sliders. After entering values for any or all of these parameters, click the “Update” button to make your values take effect.
Clipping planes appear on screen as (barely) translucent black surfaces. Click the “Hide” button in a clipping plane’s description to make it completely invisible (it still clips other objects on the screen even when invisible).
The “Save” button saves a clipping plane’s description to a file, while the “Load” button reads the description out of a file. These features are useful for saving a clipping plane even after you close the IViPP program, in order to restore it in a future run.
Clicking on the “X” in the tab at the top of a clipping plane description closes the description and removes the clipping plane.
It is possible to have multiple clipping planes active at the same time. To create additional clipping planes, simply click the page icon above the existing clipping plane descriptions. Similarly, you can make an existing description visible for review or changes by clicking its tab above the descriptions.
IViPP draws a set of coordinate axes to give a sense of position and scale to the data it displays. In principle data can be located anywhere relative to this coordinate system, but in practice IViPP is most usable if the data are located fairly near the origin and fill much of the region spanned by the axes—under these conditions the data will fill enough of IViPP’s main window to be comfortably visible, the individual steps in which IViPP zooms in or out will seem “small,” etc.
The data that IViPP visualizes are, of course, defined relative to some coordinate system of their own. IViPP assumes that it can place the origin of its coordinate axes at the origin of this data coordinate system, and tries to scale its axes to span the space occupied by the data. In many cases this means that IViPP automatically has a reasonable display of data as soon as it opens a data set, but you may sometimes need to adjust IViPP’s coordinate system manually. Two commands help you do so.
IViPP maintains a finite number (in data coordinate system units) that is large enough to act as a proxy for infinity. This “infinite” value sets the overall scale of IViPP’s coordinate system. IViPP also uses it when drawing pieces of geometry such as planes that conceptually extend to infinity. IViPP calculates this “infinite” value from the coordinate values it encounters in input files.
You can override IViPP’s calculated “infinity” with the “Set Infinity” command from the “Edit” menu. Figure 4.3 shows the resulting dialog. The number identified as “IViPP’s guess at infinite” is the value IViPP calculates would make a good substitute for infinity; clicking the “Default” button makes IViPP use this value. To use your own value, type it into the “New Infinite Value” field and click “OK.” To exit the dialog without changing the infinite value, click “Cancel.”
![[Manually Setting "Infinity"]](figures/figure_4_3.png)
Manually setting the “infinite” value when data is already loaded into IViPP will cause all data to be reloaded from its file. This is so your new setting will be used for all data in the database.
You can also relocate the origin of IViPP’s coordinate system relative to the data coordinate system. Use the “Set Origin” command in the “Edit” menu to do this. This command produces the dialog shown in Figure 4.4. Enter the data coordinates at which you want IViPP’s origin to appear in the “X,” “Y,” and “Z” fields and click “OK” to change IViPP’s origin. Clicking “Cancel” dismisses the dialog without changing the origin.
![["Set Origin" Specifies the X, Y, and Z Data Coordinates of IViPP's Origin]](figures/figure_4_4.png)
Changing IViPP’s origin causes IViPP to redraw its display immediately, without reloading any open files.
Return to the table of contents.
Previous Chapter: Viewing Particle and Geometry Data.
Next Chapter: Selectors.