Hitbox

For the website, see hitbox.tv.

An example of offensive and damageable collision bubbles in Melee, as demonstrated with Mewtwo's up aerial. Yellow bubbles are collision bubbles, and red bubbles are hitbox bubbles.

A hitbox or collision bubble (sometimes hitbubble) is the main structure for how attacks are executed in most fighting games. Attacks have one or more hitboxes associated with them, and when these hitboxes overlap with a target's damageable area (sometimes called their hurtbox or hurtbubbles), the attack is considered a hit. Hitboxes are invisible and usually, though not always, have the same shape as the attack's animation.

Overview

The two most common forms of hitbox shapes in video games are cuboids and spheres. Neither is obviously better than the other - cuboids can more easily form long or thin attacks or targets, while spheres are easier to calculate collision detection for. Smash 64 uses cuboids whereas Melee, Brawl, and SSB4 use spheres and sphere-like structures known as capsules (cylinders with spheres on the ends).

In Smash 64, hacks can enable hitbox visibility (with a few limitations), such as in this image. In Melee, hitboxes can be seen by setting DBLEVEL to DEVELOP in the debug menu. There is no easy way to display hitboxes in-game in Brawl, SSB4 or Ultimate, though a common technique in Brawl is to use hacks to place Super Scope shot visuals where the hitboxes are (which is significantly more involved a process and generally fails for any projectile or item).

Should multiple hitboxes of a single move connect with the opponent, only one of them will count. The order of precedence is known as the "hitbox stack" - hitboxes higher in the stack will override ones lower should they both hit at the same time. Mechanically, this is denoted by giving each hitbox an ID number, and lower numbers indicate higher precedence (higher stack position). For example, Marth's down aerial in Melee features its tipper hitbox on top of the stack, so hitting with both a tipper and non-tipper hitbox will result in the tipper counting (even if the majority of the opponent was hit by the other hitboxes). By contrast, the move in Brawl has the tipper on the bottom, so the tipper can only hit if none of the other hitboxes do. As a result, even through the sizes and positions of the hitboxes did not change much between games, the tipper is simple to hit with in Melee while being difficult in Brawl.

Hitboxes that are separated from a character's hurtboxes are often called disjointed, which is usually an advantage, as they can connect from a farther distance, while keeping the attacker safer from retaliation and reducing the likelihood of trading blows. Examples of disjointed hitboxes include most weapon-based attacks, and more infamously the up tilts of Kirby in Smash 64 and Snake in Brawl as well as some of Joker's moves when using Arsene.

An interesting property of hitboxes in the Smash Bros. series is that under most conditions, they occupy not only the space where they currently are, but also the space where they were one frame ago as well as all the space in between (in a straight line, regardless of what the animation might look like during intervening subframes). This characteristic is likely to prevent situations where a fast projectile may end up passing through a character in less than a frame without hitting them. On the other hand, hurtboxes do not stretch over "interframe space" in this way, so a fast-moving object (such as Fox during his Illusion) may be able to move through a slow or stationary hitbox without being damaged. In addition, certain hitboxes in Brawl use the stretch effect to create a very long hitbox, for example in Zero Laser and Aura Storm, instead of stretching over interframe space. It is unclear how the hitbox-stretching mechanism operates in Brawl when time is slowed via training mode or other effects, as Brawl renders subframes, whereas Melee and SSB64 simply reduce the overall framerate.

Hitboxes in three dimensions

While the regular camera suggests Mario should have been hit already, a side view shows otherwise.

It is a common misconception that, like some other fighting games, hitboxes and hurtboxes only operate in two dimensions. In actuality, they interact in all three dimensions equally, even though the majority of gameplay elements are restricted to two-dimensional movement. As a result, Super Smash Bros. is more accurately described as a 2.5D game.

Notable examples of unexpected behavior due to the 3D nature of hitboxes include:

• Animations where characters lean sideways can result in attacks missing them. King Dedede's sidestep in Brawl is a notorious example, allowing him to dodge attacks with narrow hitboxes even after his intangibility ends.
• Attacks that swing in a horizontal arc can hit characters of different widths at different times. For example, Peach's neutral aerial in SSB4 usually hits Zero Suit Samus a frame later than most other characters. Similarly, Yoshi's running grab in Melee is so off to the side of the playing plane that it often misses a stationary Zelda completely.

When playing on a two-dimensional stage such as Flat Zone, many of these quirks disappear, due to characters being almost completely flattened along the camera's axis. However, some new quirks can arise: if hitboxes are produced when an arcing attack is normally not yet in the playable plane, the flattening effect results in them being able to hit earlier than expected. It is also important to note that only the characters are flattened; their hitboxes and hurtboxes continue to operate as three-dimensional objects in a three-dimensional world, so maneuvers such as using the Dragoon are not affected.

Players tend to refer to any unexpected behavior of this nature as fault of the "z-axis", as z traditionally refers to the third dimension in a three-dimensional environment. This tends to result in confusion when character moveset data is decoded, as while the camera's axis is indeed along the z-axis of stages, for characters and most other gameplay objects, the z-axis is the one that points forwards.

Hitbox types

Hitbox Type	Debug mode Colour	Explanation
Offensive	Red	The standard type of attacking hitbox. From Brawl onward, there are various types of offensive hitboxes, some of which have unique abilities (like the ability to ignore shields).
Damageable	Yellow	The standard type of damageable area, also known as hurtboxes. Characters have a variety of these attached to their bodies, while damageable stage areas (such as the wedge of ice on the Summit) and non-playable entities (like enemies and bosses) use them as well.
Invincible	Green	Invincible targets can be hit by attacks but will not flinch or take any damage or knockback. For example, this occurs for characters that have just stepped off a revival platform, or who have used a Star.
Intangible	Blue	Intangible targets cannot be hit by attacks. This occurs during dodges and rolls. Various characters have attacks which provide parts of their body with intangibility, such as Mario's head during his up smash.
Reflective	Aqua	Defensive hitboxes that reflect attacks.
Shield	Cyan	Defensive hitboxes that shield attacks.
Absorbing	Cyan-blue	Defensive hitboxes that absorb attacks.
Grab	Magenta	Grab hitboxes will ignore any special or defensive hitboxes.
Inert	Grey	Inert hitboxes are used for collision detection when a regular hitbox is unsuitable (such as the dash of Raptor Boost and Gerudo Dragon).

Hitbox properties

Property	Introduced in	Description
Damage	Smash 64	The base damage dealt by the hitbox. In the first three games, the initial damage is always an integer, but it rarely ends up as one once modified by things like stale-move negation. In SSB4, damage can start at any real number.
Angle	Smash 64	The direction the target is sent flying. Usually a number from 0 to 360, with numbers such as 361 or 365 indicating the Sakurai angle or autolink angle. Can also be negative numbers such as -90.
Base knockback	Smash 64	The minimum knockback this hitbox can apply, regardless of the target's weight and damage (but dependent on type effectiveness and launch rate).
Knockback scaling	Smash 64	Modifies how much knockback rises as the target's damage increases, with the default being 100. For example, a value of 110 means that knockback will increase at a 1.1x rate compared to other hitboxes that deal the same damage.
Fixed knockback value	Smash 64	If set, causes the hitbox to deal the same knockback regardless of the target's damage.
Effect	Smash 64	Determines what happens when the hitbox connects: nothing, slashing, burning, electrocution, etc.
Groundness/Airness	Smash 64	Determines whether a hitbox can strike grounded opponents, aerial opponents, or both.
Shield damage	Smash 64	Modifies how much damage the hitbox does to shields.
Clang	Smash 64	Determines whether a hitbox can cancel out other hitboxes through priority rules.
Sound effect	Smash 64	On impact, each hitbox produces a sound effect with a given type (punch, kick, slash, shock, burn, etc.) and severity (small, medium, large; in Brawl, huge is introduced for certain types).
Reflectiveness	Smash 64	Determines whether the hitbox can be reflected. Usually a projectile.
Absorptiveness	Smash 64	Determines whether the hitbox can be absorbed. Usually a projectile.
Blockability	Melee?	Determines whether the hitbox can be shielded.
Rebound	Melee	Determines whether a move is interrupted with an animation while on the ground when it clangs with another move.
Type	Brawl	Determines what kind of stickers can power up the attack: arm, leg, body, weapon, etc.
SDI Multiplier	Brawl	Modifies how much smash directional influence can be applied when struck by this hitbox.
Freeze frames multiplier	Brawl	Changes how many freeze frames are applied on impact.
Trip chance	Brawl	Gives the hitbox an extra chance of tripping opponents.
Directness	Brawl	Determines whether the hitbox is Specials: Indirect.
Angle Flipper	Brawl	Sets whether a hitbox is allowed to hit targets the opposite direction if the target is behind the attacker, among other things.
Set Weight	Smash 4	Determines whether a hitbox considers the target's weight when knockback is calculated.
Shieldstun multiplier	Ultimate?	Changes the amount of Shieldstun the hitbox does to a shielding opponent.
Hitstun modifier	Ultimate	Changes the amount of Hitstun the hitbox does when hitting an opponent.

Trapbox

A hitbox stretching across interframe space.

In Melee, a trapbox is the hitbox left on the ground during Ness' yo-yo glitch. It is called a trapbox because this hitbox is not attached at all to any kind of attack but instead just sits wherever it was when the glitch occurred. Using a new attack will overwrite the hitbox with the new attack's properties and relocate it to the new attack, which due to the interframe stretching effect will cause it to hit everything between it and Ness.

Trivia

An example of recoil animations making hitboxes appear to be unexpectedly large. Here, Ryu is hitting Lucina with a Shoryuken, with the blue starburst showing where the collision occurred.

• In SSB, grabs are normal hitboxes with no apparent mechanism for distinction from attacks. In Melee, grab hitboxes and inert hitboxes are 0%-damage hitboxes with "grab" or "inert" for an effect. Both grabs and inert hitboxes are separate objects in Brawl and SSB4, though in rare cases a 0%-damage hitbox is used as an inert one.
• The single largest hitbox in Melee can be found when Raikou is released from a Poké Ball.
• Because characters enter a recoil animation upon being hit, pausing the game during the freeze frames can make it appear as if the attack's hitboxes are misaligned or too large.

Gallery

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  The hitboxes of Kirby's forward tilt, with Kirby's collision boxes, in the original game.

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  Various hitboxes and hurtboxes in Melee.

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  An example of a hack used to show the hitboxes of Toon Link's Spin Attack in Brawl.