RIB Fragments are used to store in files the geometry data produced right before every rendering. A RIB Fragment file contains the geometry of all objects in the fragment’s associated object set. Once the fragment file is written, subsequent renderings can simply assume that the objects in the fragment’s set have already been processed and skip several of the steps that occur before the actual image rendering begins.

RIB fragments aim to speed up multiple renderings and multi-frame renderings. When re- rendering multiple times the same frame, a single fragment will suffice. When rendering multiple frames, fragments work best when using distinct fragments for static and animated objects.

The RIB fragment files contain only geometric information about the objects. All other data, such as light linking, transformations, shading and attributes, are not stored in the fragment file. The RIB archive node is better suited when some (or all) of this extra data is needed in the file; see Section 3.11 [The RIB Archive Node], page 82.

If a scene object is set to be in several fragments, only the fragment closer to the top of the list will actually contain that object. In other words, if several fragments are used and only the last one’s "Object Set" is set to ‘<all visible objects>’, this last fragment will contain only the objects that none of the above fragments contain.

Figure 3.58: The RIB Fragments panel

Each fragment is shown in its own panel. To add a fragment, either click on the Add RIB Fragment button, or select "Add RIB Fragment" in the contextual popup menu that appears when right-clicking almost everywhere in the RIB Fragments panel. This menu also offers options to expand or collapse all display panels at once, and turn on or off all fragment’s "Use" or "Write" toggles. To remove a display, click on its Remove Display button, which appears as a trashcan.

At the top of the RIB Fragments panel are a few general controls, followed by a list of per- fragment panels. The general controls affect all RIB fragments, and are:

‘Binary Rib’

When this options is on, the RIB file will be saved in binary format, producing a smaller file. Turn this option off to produce a text RIB file, which is bigger but easier to edit. By default, this option is off.

‘Compressed Rib’
This option controls if the RIB file will be compressed, producing a smaller file. By default this option is off.

‘Write Mode’

This attribute controls when a fragment file is written. The available values are:

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‘Reuse existing fragments’
When this value is selected, 3Delight For Maya will look for the fragment file specified in the fragment’s "Filename" attribute. If the file exists, then the fragment file is assumed to be up to date, and that completes the geometry output for this fragment. If the file does not exist, it will be created unless the fragment’s "Write" attribute is turned off.

‘Overwrite existing fragments’
When this value is selected, the file specified in the fragment’s "Filename" attribute will be overwritten every time a rendering is requested, unless the fragment’s "Write" attribute is turned off. This is the default.

‘Add RIB Fragment’
Clicking on this button will create a new RIB fragment.

Each fragment has its own panel showing the attributes that are specific to that fragment.

‘Use’ When this attribute is off, the fragment is completely ignored and the objects in its "Object Set" will be output as usual. This attribute is on by default. Note that it is possible to change all fragments’ "Use" attribute at once using the contextual popup menu’s ‘Use All’ and ‘Use None’ menu options.

‘Write’ Controls if the fragment file can be written. The condition in which a fragment file is written is determined by the "Write Mode" (see [RIB fragments write mode], page 72). This attribute is on by default. Note that it is possible to change all fragments’ "Write" attribute at once using the contextual popup menu’s ‘Write All’ and ‘Write None’ menu options.

‘Remove RIB Fragment’
This button appears as a small trashcan. Clicking on this button removes the fragment from the render pass.

‘Filename’

The path of the file that will contain this fragment’s objects geometric data. If the path is relative, it is assumed to be relative to the 3Delight RIB Fragments project path (see Section 5.5.5 [Automatic File Output Control], page 126). When these objects are animated, it is recommended to add the frame number to the filename; see Section 5.5.4 [File Path Expressions], page 124 for details.

‘Browse for RIB File button’
This button, drawn as a folder, brings up a file browser to specify a RIB filename.

‘View RIB button’
This button, drawn as a magnifying glass, will open the fragment’s RIB file in a viewing application. See Section 3.17 [The Preferences Window], page 93 for details on how to specify which application should be launched.

‘Object Set’

This attribute specifies which objects are contained in the fragment’s file. If an object is set to be in several fragments, only the fragment closest to the top of the fragment list will actually contain the object. The default value is ‘<all visible objects>’, which means the fragment will contain all visible objects that are not already in a fragment above this one.