DECORATE expressions

DECORATE supports complex mathematical expressions as parameters for codepointers. (Unfortunately, expressions are not supported for the values of properties.) The expression may include standard operators (+, -, *, /, <<, >>, |, etc.), math functions, and certain actor properties (occasionally called “keywords” in the forums) to compare values with. A_JumpIf, in particular, is meant to be used with expressions, but they can be used for any numeric (integer or floating point) parameter. For example, using velx, vely, and velz in A_SpawnItemEx to preserve velocity, or using args[] as arguments to a call of ACS_Execute.

Mathematical functions

• abs(x) — returns the absolute value of x
• cos(x), sin(x) — trigonometry functions, x must be in degrees
• sqrt(x) — returns the square root of x
• random[identifier](min,max) — returns a random integer value between min and max
• random2[identifier](mask) — returns a random integer value between -mask and +mask. It is roughly equivalent to random(0, mask) - random(0, mask). If no mask is provided (random2()), the maximum value of 255 is used instead. Mask is used as a binary mask, e.g. if 9 is used, the random results can be [0, 1, 8, 9] - [0, 1, 8, 9], so it is advised to use as a mask values one less than a power of two, such as 1, 3, 7, 15, 31, 63, or 127.
• frandom[identifier](min,max) — returns a random floating point value between min and max

The identifier for random functions is optional. Calls to a random function with an identifier do not interfere with the RNG for calls with a different identifier, so using unique identifiers where appropriate reduces the risk of desync in demo playback.

ACS function

• ACS_ExecuteWithResult — runs a script and uses its return value.
• ACS_NamedExecuteWithResult — runs a named script and uses its return value.
• CallACS — shorter alias for ACS_NamedExecuteWithResult.

Variables

There are a few variables you can use for dynamic data in DECORATE definitions. These are:

Actor position and movement

• x — The actor's X position in the world.
• y — Same, but for Y.
• z — Same, but for Z.
• angle — Actor's angle, in degrees
• ceilingz — See GetActorCeilingZ
• floorz — See GetActorFloorZ
• pitch — The actor's pitch. (Presumably, in degrees, based on the above.)
• velx or momx — Actor's velocity along the absolute X axis. The "mom" names are (deprecated).
• vely or momy — Same, but for Y.
• velz or momz — Same, but for Z.

Actor properties

• accuracy — The accuracy of the Actor.
• alpha — The Alpha value of the Actor.
• args[] — Arguments passed to the thing special; args[0] through args[4] are valid.
• damage — The actor's Damage.
• health — How much health the Actor has left.
• height — The actor's Height. (development version r3955+ only)
• mass — The actor's Mass.
• radius — The actor's Radius. (development version r3955+ only)
• reactiontime — The actor's ReactionTime. (development version r4222+ only)
• scaleX — The actor's horizontal scale. See A_SetScale.
• scaleY — The actor's vertical scale. See A_SetScale.
• score — The actor's score.
• special — ID of the special currently assigned to this actor
• stamina — The stamina of the Actor.
• tid — The actor's TID
• tidtohate — TID of the current target (see Thing_Hate et al.)
• User Variables — user variables are defined as "var int user_(name);" in actor properties
• User Arrays — user arrays are defined as "var int user_(name)[(size)];" in actor properties
• waterlevel — How "submerged" the actor is in a Transfer_Heights or 3D floor water pool:

0: Not submerged at all (e.g. standing on solid ground or on shallow TERRAIN-based water)

1: Less than half submerged ("ankle deep")

2: At least half submerged ("waist deep")

3: Entirely submerged (completely underwater)

Examples

See Projectile Trap