SPR files are simple text files which contain sprite information, for example bubbles, explosions and splashes.
Each SPR file has only one line of information, sans comments:
#material type width height geo light tex extralight xoff yoff zoff debrisx.mat 0 0.05 0.05 4 0 0 0.0 0.0 0.00 0.0
|Attribute Name||Data Type||Description|
|material||string||MAT file to use for the sprite|
|type||integer||Always seems to equal 0|
|width||float||width of the sprite|
|height||float||height of the sprite|
|geo||integer||geometry mode (always 4, except in twinke.spr where it is 3)|
|light||integer||lighting mode (always seems to be 0)|
|tex||integer||texture mode (always seems to be 0)|
|extralight||float||light intensity of sprite above its surroundings|
|xoff, yoff, zoff||float||Offsets float insertion by value, presumably in JKUs|
Note: together, width and height seem to determine the size of the sprite. This probably means that each sprite is rectangular in shape, with the 4 corners of the MAT fitted to the sprite's 4 corners. Consider the 3 bubble sprites: each are identical except that they have different sizes.