# Creating and Importing Cel Components

Cel components are typically created using 3DO tools designed specifically for that purpose. For example, the source data for a cel is often created in a paint program in a development system, and is then saved in whatever format (coded or uncoded, packed or unpacked) is appropriate for the cel. The program saves the source data in a single file with an appropriate preamble prefixed to the source data. If the cel was created with a custom palette, that palette may be saved in a separate file as a custom PLUT to be used with the cel. The program may even create a default CCB for the cel and save it in a third file.

Precreated cel components are very convenient, and allow artists full use of artistic tools to create cel contents, but almost all cels must have at least one component changed or created by the program on the fly-typically the CCB, which must be changed to simply move a cel across the screen or to change the size of the cel. Other cel components may be changed or created within Portfolio as well. The typical example is a cel whose pixels come from an existing bitmap. The cel's preamble is created by the program; the preamble specifies a rectangle within the bitmap as the source data. The cel engine projects the pixels within the rectangle as the cel pixels. The program can change the preamble between cel projection calls to specify new sections of the bitmap for projection.