A basic CLSN tutorial for all characters by K.O.D (updated on October 04, 2009)

CLSN2 : Collision box (Blue)
CLSN1 : Hit box (Red)

Keep in mind all these :
1. If the character is an existing game character (King of Fighters, Akatsuki Blitzkampf, etc.) with a CLSN viewer, take the CLSN data directly from it which is much simpler than explanation (disregard this tutorial)
2. Basic rule in all good fighting games : 2 CLSN2 boxes on each animation (at maximum 4 boxes if the sprite is huge, etc.)
3. Basic rule in all good fighting games : 1 CLSN1 box on each animation (maximum 2 boxes, but it can be increased to 4 if the animation is a slanted projectile,etc.)
4. Position your boxes a bit out of torso range but within the arm's range.
5. Always use the same CLSN boxes in the standing animation, do not change the clsn boxes in any frame of the standing animation (unless it's a special character which has a complicated stand animation)
6. Use CLSN Default for a CLSN1/CLSN2 box which is the same in all frames.
7. Do not make the CLSN boxes move unnecessarily in the animation just for a single limb or head movement,etc.

Note : Even though the character I'm using as an example for this tutorial is a King of Fighters character, I will change his CLSN boxes just for the sake of demonstration.


An example of good standing CLSN2 boxes (clean and practical) :



An example of bad standing CLSN2 boxes (too many unnecessary details which do not have any effect in gameplay and causes lag on slow PC's) :




Moves which evade High or Low attacks do not have any special property set for them, instead, the CLSN2 boxes of the move are positioned so that the opponents hitbox does not hit the player.

This move has Kyo ducking (crouching) before attacking the opponent, the effect is by the CLSN2 position :



This move has Kyo hopping before attacking the opponent, the effect is by the CLSN2 position :




Moving onto CLSN1 boxes, there is a thing known as "infinite priority" which is caused by not overlapping a CLSN1 box with a CLSN2 box which in turn makes the attacker "cheap" by allowing him to attack without getting hit back.

Remember that Infinite Priority is NOT applicable to some fighting games which have clever CLSN positioning to further enhance the "realism" of the gameplay (KoF, Fatal Fury, Melty Blood, etc.) so do not apply the infinite priority rule to games which do not follow it as they are meant for their own gameplay style.

Also, swords or any other weapons do not need to have a CLSN2 overlapping the CLSN1 boxes on them, CLSN1 boxes must be within in the range of the hand/sword/etc. and not covering much more (however, sword "slashes" can have a wider CLSN1 box to give accuracy to the slash)

An example of good attack CLSN1 boxes (within range and practical)



An example of good jumping attack CLSN1 boxes (within range, practical and does not need multiple boxes)



An example of bad attack CLSN1 boxes (has infinite priority, unrealistic and time consuming)



An example of bad jumping attack CLSN1 boxes (has infinite priority, unrealistic and time consuming)




Same rules apply for projectiles, keep them within range and keep them clean.

Projectiles need to have a CLSN2 box covering the CLSN1 box (even in KoF characters) for getting hit by other projectiles/blocking other projectiles depending on what type of projectile you are coding.