Editing Guide:Animation (section)

=== Doom Sprite animation system ===
Weissblatt's sprite animation system works by appending a ''frame'' and an ''angle'' to the name of your sprite's lump name. For example, the animation <code>WALK</code> may consist of the frames <code>WALKA0</code>, <code>WALKB0</code>, <code>WALKC0</code> and <code>WALKD0</code>. The frame is determined by a letter A to Z, while the angle is determined by a number.

Any sprite may be assigned to one or two frame-angle-pairs. When a second frame-angle pair is given, it will be displayed by horizontally flipping the sprite along it's offset. For example a single sprite may be called <code>WALKA3A7</code> to be used as both a left-facing and a right facing sprite.

The following table explains how the angle numbers are assigned:

{| class="wikitable"
|+Sprite angle system
|'''A4'''
(Back-Left diagonal)
|AC
|'''A5'''
(Back)
|AD
|'''A6'''
(Back-Right diagonal)
|-
|AB
| colspan="3" rowspan="3" |'''A0'''
(Billboarding)
|AE
|-
|'''A3/AL'''
(Left)
|'''A7/AR'''
(Right)
|-
|AA
|AF
|-
|'''A2'''
(Front-Left diagonal)
|A9
|'''A1'''
(Front)
|AG
|'''A8'''
(Front-Right diagonal)
|}
Sprites can be defined in multiple modes, depending on which angle is loaded last missing frames will result in an error:

# '''A0 mode''': Only an A0 angle is defined and the sprite is billboarded. This is usually used by decorative objects.
# '''Left-Right mode''': Only the angles AL and AR are defined. The sprite will always be facing either left or right, akin to a 2D game.
# '''Eight-Angle mode''': Angles A1 to A8 are required. This is the mode used by most characters and enemies.
# '''Sixteen-Angle mode''': Angles A1 to AG are required. This is used by the 8 ball.