Object Flags

Object Flags are a series of toggles that determine the properties of an Object. They are used for a variety of different purposes, such as the Object's interaction with the level environment and other Objects as well as the type of thinker it uses. Some of them have very specific uses while others set more general options.

There are two sets of flags: The regular FLAGS are the basic properties that must be set for every Object and that are checked on level load. In most cases, these properties won't change in-game. In contrast to these, the FLAGS2 are used for temporary properties that are added and removed by certain actions for short periods of time. While the FLAGS must be set for every custom Object in its SOC block, the FLAGS2 can only be set during runtime.

Every flag has a unique numerical value. To set a flag for an Object, its value must be added to the FLAGS property in the SOC block of that Object. The SRB2 SOC Editor lists the Object's FLAGS in the form of checkboxes, allowing users to set the flags without calculating the resulting value. However, not all FLAGS are listed correctly. The FLAGS2 are generally used for very specific purposes and rarely need to be modified manually, but if it is necessary, they can be modified with the action A_SetObjectFlags2. A_SetObjectFlags does the same for the Object's FLAGS if it is necessary to modify them during runtime.

Object Flags

Decimal	Hexadecimal	Flag Name	Description
1	0x00000001	MF_SPECIAL	When an Object with this flag is touched by the player, the function P_TouchSpecialThing is called to determine what should happen with the Object and/or the player. Objects that interact with the player in some way upon being touched, such as enemies, hazards or collectible items, should have this flag.
2	0x00000002	MF_SOLID	This makes the Object solid, and it will act as such to the player. Note that without MF_PUSHABLE or MF2_STANDONME, the player will not be able to properly stand on the Object.
4	0x00000004	MF_SHOOTABLE	The Object can be damaged. Combined with MF_SOLID, this makes it vulnerable to missiles, but not normal attacks.
8	0x00000008	MF_NOSECTOR	Removes the Object from the sector links, making it invisible. Don't change this flag during runtime. To make something invisible during the game, use MF2_DONTDRAW or set the sprite to SPR_DISS.
16	0x00000010	MF_NOBLOCKMAP	Removes the Object from the blockmap, making it intangible. Just like MF_NOSECTOR though, don't change this flag during runtime - use MF_NOCLIP instead.
32	0x00000020	MF_AMBUSH	This flag is used for various purposes, usually to signify an alternate type of behavior for an Object. Its effect depends on the Object's other flags and the actions being used. Checking the Ambush flag on a Thing will usually activate this flag for the corresponding Object.
64	0x00000040	MF_PUSHABLE	The Object can be pushed around, stood upon, and will crush players should it fall on them. It can also activate Trigger Linedef Executor (Pushable Objects). The Object's ActiveSound will be played when the Object is pushed. MF_SOLID has to be checked for this to work.
128	0x00000080	MF_BOSS	The Object is a boss and will use a boss thinker. See Custom Boss Tutorial for further details.
256	0x00000100	MF_SPAWNCEILING	The Object spawns on the ceiling rather than the floor.
512	0x00000200	MF_NOGRAVITY	The Object is unaffected by gravity and will keep its height unless moved by something else.
1024	0x00000400	MF_AMBIENT	The Object is an ambient sound effect. The Object's SeeSound is constantly played. SpawnHealth sets the interval between each time SeeSound is played.
2048	0x00000800	MF_SLIDEME	The Object will slide along walls when touching them instead of turning around.
4096	0x00001000	MF_NOCLIP	The Object is intangible and will go through walls and other Objects. When NOCLIP is turned on, the player will be given this flag.
8192	0x00002000	MF_SPECIALFLAGS	This flag is used internally to prevent the Star Post from adhering to regular flag/Z offset properties in Objectplace mode. It has no effect for custom Objects.
16384	0x00004000	MF_FLOAT	The Object (most likely to be an enemy) can change its height in midair. MF_NOGRAVITY has to be checked for this to work.
32768	0x00008000	MF_BOXICON	The Object is a monitor icon and will float upwards upon being spawned. Damage sets how high the Object will rise before disappearing, and Speed sets how fast it will rise.
65536	0x00010000	MF_MISSILE	The Object is a projectile of some sort. While moving, it will have no friction, go into its DeathState on collision with anything other than its target, and damage anything other than its target. It will play its SeeSound upon being fired, and its DeathSound upon colliding with something.
131072	0x00020000	MF_SPRING	The Object is a spring and will be treated as such when touched. See the Spring article for further details.
262144	0x00040000	MF_BOUNCE	The Object will bounce off walls and other Objects, playing its ActiveSound whenever this happens.
524288	0x00080000	MF_HIRES	The Object uses a high-resolution sprite. For Character WADs, setting highres to 1 will give the player this flag.
1048576	0x00100000	MF_MONITOR	The Object is a monitor; it will be popped when hit by a normal attack from the player and award a power. If the Object falls on a player, the player will be crushed and die.
2097152	0x00200000	MF_NOTHINK	The Object has no AI. Use this to save CPU power for static scenery Objects.
4194304	0x00400000	MF_FIRE	The Object is flaming; it will hurt players without an Elemental Shield and vanish when it touches water.
8388608	0x00800000	MF_NOCLIPHEIGHT	The Object is not restricted to the top and bottom heights of the sector it is in, and can go into the floor or ceiling. The SOC editor incorrectly lists this as MF_COUNTITEM. Objects with the MF_MISSILE flag use this for a different purpose: When a missile explodes, this flag is set to indicate that is has exploded and prevent it from exploding again.
16777216	0x01000000	MF_ENEMY	The Object is an enemy; it can hurt the player, can be killed by various means, and gives the player who killed it 100 points.
33554432	0x02000000	MF_SCENERY	The Object is scenery and uses a reduced thinker for scenery items. It can't do anything, but it takes up less CPU power than a regular Object.
67108864	0x04000000	MF_TRANSLATION	The Object is drawn with interchangeable colors that can be modified during runtime. One example of this are the team rings, whose sprites have a green placeholder color and whose actual color is determined in-game, depending on which team they belong to. The SOC editor does not list this flag.
1073741824	0x40000000	MF_NOCLIPTHING	The Object is partially intangible, it will pass through other Objects, but not walls. This is used for the animals that are released from destroyed enemies, for example.
2147483648	0x80000000	MF_RUNSPAWNFUNC	Normally a Object cannot perform actions during its SpawnState, this flag makes it able to. The SOC editor does not list this flag, and will crash if an Object with this flag is viewed.

Object Flags 2

Decimal	Hexadecimal	Flag Name	Description
1	0x00000001	MF2_PUSHED	A temporary flag that is set by various pusher functions to indicate that the Object was already pushed and shouldn't be pushed again during this tic. It is automatically reset at the start of each tic.
2	0x00000002	MF2_AXIS	This flag is automatically set for the NiGHTS Axis, Axis Transfer and Axis Transfer Line. It is used internally to make it more convenient to check if an Object is one of those three.
4	0x00000004	MF2_DONTRESPAWN	The Object does not respawn. Given to any items dropped by players who have been hit.
8	0x00000008	MF2_RINGORHOOP	This flag is unused.
16	0x00000010	MF2_FRET	This flag is used to signify that a boss has been hit by the player. Among other things, it makes the boss's sprites flash white and makes it temporarily immune to the player.
32	0x00000020	MF2_INFLOAT	If an Object has the MF_FLOAT flag set, it automatically floats at the height of its target. If it shouldn't do that, this flag is used.
64	0x00000040	MF2_DEBRIS	Exploded Explosion Rings and Grenade Rings are given this flag to signify that they have already exploded.
128	0x00000080	MF2_TWOD	This flag is given to Objects if they are in 2D Mode or are supposed to behave as such.
256	0x00000100	MF2_NIGHTSPULL	This flag is used for the item attraction in NiGHTS Mode. Rings, Coins and Wing Logos that are inside the player's attraction radius are given this flag.
512	0x00000200	MF2_JUSTATTACKED	The Object has just attacked, and cannot attack again immediately. Objects using A_Chase and A_SkimChase, or Objects with MF_BOSS, add this flag when they first attack - when they try to attack again, this flag is removed instead of attacking, and then the process repeats again once they are ready to attack again. CTF flags have this flag set when they are outside their respective bases.
1024	0x00000400	MF2_FIRING	This flag is used signify that an Object is currently firing some type of projectile. Used by the Turret and the Flame Jets. A_TurretFire and A_SuperTurretFire add this flag to the Object, A_TurretStop removes it, whilst A_ToggleFlameJet can do either depending on whether the flag is already set or not.
2048	0x00000800	MF2_ONMOBJ	The Object is resting on top of another Object.
4096	0x00001000	MF2_SKULLFLY	This flag is set by the action A_SkullAttack to signify that the Object is currently flying at the player. If the Object is the Egg Mobile or a custom Object with MF_BOSS, ghost trails of the Object will be spawned while this flag is set.
8192	0x00002000	MF2_CHAOSBOSS	This flag was used to separate bosses that are spawned in Chaos mode from regular bosses, to make sure that defeating a Chaos boss doesn't end the level.
16384	0x00004000	MF2_BOSSNOTRAP	This flag is given to bosses whose map Things have the Object Special flag checked. If the flag is set and A_BossDeath is called, no Egg Trap Capsule will appear and the level will end instead. Also used as a dummy flag to mark popped monitors.
32768	0x00008000	MF2_BOSSFLEE	This flag is given to bosses who are fleeing to control their movement.
65536	0x00010000	MF2_AUTOMATIC	This flag is given to thrown Automatic Rings to identify them as such.
131072	0x00020000	MF2_RAILRING	This flag is given to thrown Rail Rings to identify them as such.
262144	0x00040000	MF2_BOUNCERING	This flag is given to thrown Bounce Rings to identify them as such.
524288	0x00080000	MF2_EXPLOSION	This flag is given to thrown Explosion Rings to identify them as such.
1048576	0x00100000	MF2_SCATTER	This flag is given to thrown Scatter Rings to identify them as such.
2097152	0x00200000	MF2_GRENADE	This flag is given to thrown Grenade Rings to identify them as such.
4194304	0x00400000	MF2_DONTDRAW	The Object does not generate a visible sprite.
8388608	0x00800000	MF2_SLIDEPUSH	The Object slides after being pushed. MF_SOLID and MF_PUSHABLE have to be checked for this to work. The maximum speed at which an Object with this flag can slide is set by its Speed value.
16777216	0x01000000	MF2_SHADOW	The Object is drawn fuzzy, which makes targeting harder. Set by the Force Shield when it has only one health point left. Also used to make the player translucent when the camera is too close in Single Player.
33554432	0x02000000	MF2_STANDONME	The Object can be stood on even if it doesn't have the MF_PUSHABLE flag set. MF_SOLID has to be checked for this to work.
67108864	0x04000000	MF2_SUPERFIRE	This flag is given to projectiles that can stop Super Sonic as well as the Objects that fire them.
134217728	0x08000000	MF2_CLASSICPUSH	If the Object is falling, it will stop all horizontal movement and drop straight down. This flag is given to pushables whose map Things have both the Object Special and Ambush flag checked.
268435456	0x10000000	MF2_STRONGBOX	This flag is given to Strong Random Monitors to identify them as such.
536870912	0x20000000	MF2_REFLECTED	This flag is given to weapons that were reflected by the Force Shield.
1073741824	0x40000000	MF2_OBJECTFLIP	This flag is given to Objects whose gravity is permanently flipped.