Spin resources contain sprite info. Whenever EV needs to load a set of sprites for a particular object, it looks at that objects's spin resource, which in turn tells the game how to load the object's sprites. EV sprites are stored as paired sprite and mask PICT resources. The sprites in each PICT are arranged in a grid, which can be of any size. The spin resource tells EV what shape and size the sprites' grid is. Spin resources have the following fields:
SpritesID ID number of the sprites' PICT resource
MasksID ID number of the masks' PICT resource
xSize Horizontalsize of each sprite (should be a multiple of 8!)
ySize Verticalsize of each sprite
xTiles Horizontalgrid dimension
yTiles Verticalgrid dimension
Spin resources have certain reserved ID numbers, which correspond to different types of objects:
128-191 Ships
200-263 Weapons
300-363 Stellar objects
400-402 Explosions
500 Boxes
It is important to note that the ID numbers of the PICT resources are non-critical, as EV looks at the spin resources to find the sprites, and not at the actual PICT ID numbers themselves.
Note: The total number of sprites in the graphics file (used by EV to update the progress bar during startup time) is stored in 'spït' resource 128 in the EV Graphics file.