Particle Script

This file format is almost completely documented Elements beyond MP1 need to be discovered and documented

Retro games feature a uniform, fixed-function Particle Script system for describing various geometrical effects and weapon systems. The PAK archives contain binary resources using FourCCs to build a key-value dictionary. These codes correspond to application-specific parameters controlling the system in question.

The scripts use a dataflow paradigm built around value-generating element classes of the following types:

• Int
• Real (float)
• Vector (3-component float)
• Mod Vector (3-component float)
  • Local velocity vector in/out
  • Local position vector in/out
• Color (4-component float, internally converted to RGBA8)
• UV (TXTR reference and UV coordinate source)
• Emitter
  • Initial local position vector (3-component float)
  • Initial local velocity vector (3-component float)

The system features several subclasses that output generated values through GetValue as a function of the current frame index. These implementations may recursively accept input from other elements, permitting effect designs of scalable complexity.

File Layout

All effect script file formats are read linearly to populate a description tree of element nodes, serving as a template to build an arbitrary number of generator instances:

• Script Magic FourCC (see table below)
• Parameters
  • Key FourCC
  • Value Parameter(s) (one of:)
    • NONE: null value (equivalent to not specifying the key at all)
    • Element FourCC (see below)
      • Child Elements (count/types according to parent)
• _END

Script Types

Type	Magic	Purpose
PART	GPSM	Particle element generator
SWHC	SWSH	Swoosh generator
ELSC	ELSM	Electric generator
DPSC	DPSM	Decal generator
WPSC	WPSM	Projectile weapon configuration
CRSC	CRSM	Projectile collision response configuration

Elements

Many of the animated qualities in particle scripts are achieved with dynamic elements. These elements provide I/O interfaces and internally process numeric data that passes through. They may also gather data from other sources within the particle system's state.

Int Elements

FourCC	Parameters	Description	Notes	MP1	MP2	MP3	DKCR	DKCTF
ADD_	(IntElement a, IntElement b)	Add	Returns a + b	✔	✔	✔	✔	✔
CHAN	(IntElement a, IntElement b, IntElement thresholdFrame)	Time Chain	Returns a when current frame index is less-than thresholdFrame, otherwise b	✔	✔	✔	✔	✔
CLMP	(IntElement min, IntElement max, IntElement val)	Clamp	Returns val clamped between min and max	✔	✔	✔	✔	✔
CNST	(s32 value)	Constant	Returns value on every call	✔	✔	✔	✔	✔
DETH	(IntElement passthrough, IntElement thresholdFrame)	Death	Always returns passthrough, and signals out-of-band to cease updating the system when the current frame index exceeds thresholdFrame	✔	✔	✔	✔	✔
GAPC	()	Get Active Particle Count	Accesses the current count of particles in the system	✔	✔	✔	✔	✔
GEMT	()	Get Emitter Time	Accesses the current frame count for the current particle system	✔	✔	✔	✔	✔
GTCP	()	Get Cumulative Particle Count	Accesses the total number of particles created over the particle system's lifetime (including those that have died)	✔	✔	✔	✔	✔
ILPT	(IntElement percent)	Lifetime Percent	Queries the frame index at percent/100.0 into the lifetime of the particle instance	✔	✔	✔	✔	✔
IMPL	(IntElement val)	Impulse	Returns val ONLY at frame index 0, then returns 0 for subsequent frames	✔	✔	✔	✔	✔
IRND	(IntElement a, IntElement b)	Initial Random	Rolls a random value between a and b on frame index 0; returns that value for subsequent frames	✔	✔	✔	✔	✔
KEYE	(KeyframeEmitterData data)	Keyframe Emitter	List of synchronized animation keys	✔	✔	✔	✔	✔
KEYP	(KeyframeEmitterData data)	Keyframe Emitter	List of percentage-tweened animation keys	✔	✔	✔	✔	✔
MODU	(IntElement a, IntElement b)	Modulo	Returns a % b	✔	✔	✔	✔	✔
MULT	(IntElement a, IntElement b)	Multiply	Returns a * b	✔	✔	✔	✔	✔
PULS	(IntElement aDuration, IntElement bDuration, IntElement a, IntElement b)	Pulse	Returns a for aDuration frames then b for bDuration frames, then repeats this cycle	✔	✔	✔	✔	✔
RAND	(IntElement a, IntElement b)	Random	Rolls a random value between a and b	✔	✔	✔	✔	✔
SPAH	(IntElement val, IntElement waitMin, IntElement waitMax)	Sample And Hold	Stores val for a random count of frames between waitMin and waitMax and repeats this cycle	✔	✔	✔	✔	✔
SUB_	(IntElement a, IntElement b)	Subtract	Returns a - b	✔	✔	✔	✔	✔
TSCL	(RealElement dv)	Time Scale	Returns dv times the current frame index (rounding down to nearest integer)	✔	✔	✔	✔	✔

Real Elements

FourCC	Parameters	Description	Notes	MP1	MP2	MP3	DKCR	DKCTF
ADD_	(RealElement a, RealElement b)	Add	Returns a + b	✔	✔	✔	✔	✔
CEQL	(RealElement ca, RealElement cb, RealElement pass, RealElement fail)	Compare Equals	Returns pass if ca and cb are within 0.00001 difference, otherwise fail	✔	✔	✔	✔	✔
CEXT	(IntElement a)	Unknown	Involves a lookup table	✔	✔	✔	✔	✔
CHAN	(RealElement a, RealElement b, IntElement thresholdFrame)	Time Chain	Returns a when current frame index is less-than thresholdFrame, otherwise b	✔	✔	✔	✔	✔
CLMP	(RealElement min, RealElement max, RealElement val)	Clamp	Returns val clamped between min and max	✔	✔	✔	✔	✔
CLTN	(RealElement ca, RealElement cb, RealElement pass, RealElement fail)	Compare Less-Than	Returns pass if ca is less-than cb, otherwise fail	✔	✔	✔	✔	✔
CNST	(float value)	Constant	Returns value on every call	✔	✔	✔	✔	✔
CRNG	(RealElement val, RealElement min, RealElement max, RealElement inRange, RealElement outOfRange)	Constant Range	Returns inRange if val is between min and max, otherwise outOfRange	✔	✔	✔	✔	✔
DOTP	(VectorElement a, VectorElement b)	Dot Product	Returns a · b	✔	✔	✔	✔	✔
GTCR	(ColorElement color)	Get Component Red	Extracts red component from color	✔	✔	✔	✔	✔
GTCG	(ColorElement color)	Get Component Green	Extracts green component from color	✔	✔	✔	✔	✔
GTCB	(ColorElement color)	Get Component Blue	Extracts blue component from color	✔	✔	✔	✔	✔
GTCA	(ColorElement color)	Get Component Alpha	Extracts alpha component from color	✔	✔	✔	✔	✔
IRND	(RealElement a, RealElement b)	Initial Random	Rolls a random value between a and b on frame index 0; returns that value for subsequent frames	✔	✔	✔	✔	✔
ISWT	(RealElement a, RealElement b)	Initial Switch	Returns a ONLY at frame index 0, then returns b for subsequent frames	✔	✔	✔	✔	✔
ITRL	(IntElement a, RealElement b)	Int Times Real	Returns a * b	✔	✔	✔	✔	✔
KEYE	(KeyframeEmitterData data)	Keyframe Emitter	List of synchronized animation keys	✔	✔	✔	✔	✔
KEYP	(KeyframeEmitterData data)	Keyframe Emitter	List of percentage-tweened animation keys	✔	✔	✔	✔	✔
LFTW	(RealElement a, RealElement b)	Lifetime Tween	Linearly-interpolates a to b over the lifetime of the particle instance	✔	✔	✔	✔	✔
MULT	(RealElement a, RealElement b)	Multiply	Returns a * b	✔	✔	✔	✔	✔
PAPn	()	Particle System Advance Parameter	Accesses the value stored into ADV[1-8] for each system update	✔	✔	✔	✔	✔
PRLW	()	Particle Rotation or Line Width	Returns the rotation (in degrees) or line width for the current particle instance	✔	✔	✔	✔	✔
PSLL	()	Particle Size or Line Length	Returns the size or line length for the current particle instance	✔	✔	✔	✔	✔
PULS	(IntElement aDuration, IntElement bDuration, RealElement a, RealElement b)	Pulse	Returns a for aDuration frames then b for bDuration frames, then repeats this cycle	✔	✔	✔	✔	✔
RAND	(RealElement a, RealElement b)	Random	Rolls a random value between a and b	✔	✔	✔	✔	✔
RLPT	(RealElement percent)	Lifetime Percent	Queries the frame index at percent/100.0 into the lifetime of the particle instance	✔	✔	✔	✔	✔
SCAL	(RealElement dv)	Time Scale	Returns dv times the current frame index	✔	✔	✔	✔	✔
SINE	(RealElement magnitude, RealElement linearAngle, RealElement constantAngle)	Sine Wave	Returns sin((curFrame * linearAngle + constantAngle) * π / 180.0) * magnitude	✔	✔	✔	✔	✔
SUB_	(RealElement a, RealElement b)	Subtract	Returns a - b	✔	✔	✔	✔	✔
VMAG	(VectorElement vec)	Vector Magnitude	Computes magnitude (length) of vec	✔	✔	✔	✔	✔
VXTR	(VectorElement vec)	Vector X To Real	Extracts X component of vec	✔	✔	✔	✔	✔
VYTR	(VectorElement vec)	Vector Y To Real	Extracts Y component of vec	✔	✔	✔	✔	✔
VZTR	(VectorElement vec)	Vector Z To Real	Extracts Z component of vec	✔	✔	✔	✔	✔

Vector Elements

FourCC	Parameters	Description	Notes	MP1	MP2	MP3	DKCR	DKCTF
ADD_	(VectorElement a, VectorElement b)	Add	Returns a + b	✔	✔	✔	✔	✔
ANGC	(RealElement angleXBias, RealElement angleYBias, RealElement angleXRange, RealElement angleYRange, RealElement magnitude)	Angle Cone	Generates a random vector based on (0,0,1) rotated about the X/Y axis. The angles of rotation (in degrees) are set by random ranges angleXRange and angleYRange, centered around non-random angleXBias and angleYBias. The resulting vector's length is set as magnitude.	✔	✔	✔	✔	✔
CCLU	(VectorElement circleOffset, VectorElement circleNormal, IntElement cycleFrames, RealElement randomFactor)	Circle Cluster	Generates a vector along an angular sweep of a unit-circle offset by circleOffset, oriented according to circleNormal. The sweep makes a full rotation within the circle over cycleFrames. The resulting vector has a randomized 3D jitter added; scaled by randomFactor times the intermediate magnitude.	✔	✔	✔	✔	✔
CHAN	(VectorElement a, VectorElement b, IntElement thresholdFrame)	Time Chain	Returns a when current frame index is less-than thresholdFrame, otherwise b	✔	✔	✔	✔	✔
CIRC	(VectorElement circleOffset, VectorElement circleNormal, RealElement angleConstant, RealElement angleLinear, RealElement circleRadius)	Circle	Generates a vector along an angular sweep of a circle of circleRadius offset by circleOffset oriented according to circleNormal. The sweep angle (in degrees) is calculated as (angleLinear * curFrame + angleConstant).	✔	✔	✔	✔	✔
CNST	(RealElement x, RealElement y, RealElement z)	Constant	Composes a vector from 3 float components. If all 3 components are Constant, then the internal representation is an optimized CVector3f data-structure.	✔	✔	✔	✔	✔
CONE	(VectorElement direction, RealElement baseRadius)	Cone	Generates a vector within a cone directed towards direction; with the cone's base limited by min(1.0, baseRadius)	✔	✔	✔	✔	✔
CTVC	(ColorElement color)	Color To Vector	Converts RGB components of color to a 3-component vector	✔	✔	✔	✔	✔
KEYE	(KeyframeEmitterData data)	Keyframe Emitter	List of synchronized animation keys	✔	✔	✔	✔	✔
KEYP	(KeyframeEmitterData data)	Keyframe Emitter	List of percentage-tweened animation keys	✔	✔	✔	✔	✔
MULT	(VectorElement a, VectorElement b)	Multiply	Returns a * b	✔	✔	✔	✔	✔
PLCO	()	Previous Particle Location	Accesses the location (world space) of the current particle instance on the previous frame (or current frame if at frame 0)	✔	✔	✔	✔	✔
PLOC	()	Particle Location	Accesses the location (world space) of the current particle instance	✔	✔	✔	✔	✔
PSOF	()	Particle System Forward	Accesses the local forward-pointing vector of the current particle system, oriented in world space	✔	✔	✔	✔	✔
PSOU	()	Particle System Up	Accesses the local up-pointing vector of the current particle system, oriented in world space	✔	✔	✔	✔	✔
PSOR	()	Particle System Right	Accesses the local right-pointing vector of the current particle system, oriented in world space	✔	✔	✔	✔	✔
PSTR	()	Particle System Translation	Accesses the translation vector (world space) of the current particle system	✔	✔	✔	✔	✔
PULS	(IntElement aDuration, IntElement bDuration, VectorElement a, VectorElement b)	Pulse	Returns a for aDuration frames then b for bDuration frames, then repeats this cycle	✔	✔	✔	✔	✔
PVEL	()	Particle System Velocity	Accesses the velocity vector (world space) of the current particle instance	✔	✔	✔	✔	✔
RTOV	(RealElement val)	Real To Vector	Assigns val to all 3 components of the returned vector	✔	✔	✔	✔	✔
SUB_	(VectorElement a, VectorElement b)	Subtract	Returns a - b	✔	✔	✔	✔	✔

Mod Vector Elements

FourCC	Parameters	Description	Notes	MP1	MP2	MP3	DKCR	DKCTF
BNCE	(VectorElement planePoint, VectorElement planeNormal, RealElement friction, RealElement restitution, bool dieOnPenetrate)	Bounce	Maintains the state of an unbounded plane in local space, defined by planePoint and planeNormal. If the particle's position penetrates this plane, it will either be destroyed if dieOnPenetrate is set, or a deflection will occur. This deflection accounts for friction along the plane and restitution of the objects represented by the particles.	✔	✔	✔	✔	✔
CHAN	(ModVectorElement a, ModVectorElement b, IntElement thresholdFrame)	Time Chain	Returns a when current frame index is less-than thresholdFrame, otherwise b	✔	✔	✔	✔	✔
CNST	(RealElement x, RealElement y, RealElement z)	Constant	Composes a mod vector from 3 float components. If all 3 components are Constant, then the internal representation is an optimized CVector3f data-structure. This vector overrides the particle's velocity in units/frame.	✔	✔	✔	✔	✔
EMPL	(VectorElement implodePoint, RealElement velocityScale, RealElement maxRadius, RealElement minRadius, bool enableMinRadius)	Exponential Implosion	Integrates a cumulative implosion force over time by influencing the velocity of particles within maxRadius of implodePoint (and outside minRadius if enableMinRadius set). The velocity of these particles is set as (particleVelocity + velocityScale * (implodePoint - particlePosition)) units/frame.	✔	✔	✔	✔	✔
EXPL	(RealElement impulseMagnitude, RealElement falloffFactor)	Explode	Rolls a random, normalized vector scaled by impulseMagnitude on frame 0 and sets this as the particle's velocity in units/frame. Subsequent frames multiply the velocity by falloffFactor.	✔	✔	✔	✔	✔
GRAV	(VectorElement acceleration)	Gravity	Integrates a simple cumulative acceleration in units/frame2	✔	✔	✔	✔	✔
IMPL	(VectorElement implodePoint, RealElement velocityScale, RealElement maxRadius, RealElement minRadius, bool enableMinRadius)	Implosion	Integrates a cumulative implosion force-differential over time by influencing the velocity of particles within maxRadius of implodePoint (and outside minRadius if enableMinRadius set). The velocity of these particles is set as (particleVelocity + (velocityScale / magnitude(implodePoint - particlePosition)) * (implodePoint - particlePosition)) units/frame.	✔	✔	✔	✔	✔
LMPL	(VectorElement implodePoint, RealElement velocityScale, RealElement maxRadius, RealElement minRadius, bool enableMinRadius)	Linear Implosion	Integrates a non-cumulative implosion force-differential over time by influencing the velocity of particles within maxRadius of implodePoint (and outside minRadius if enableMinRadius set). The velocity of these particles is set as ((velocityScale / magnitude(implodePoint - particlePosition)) * (implodePoint - particlePosition)) units/frame.	✔	✔	✔	✔	✔
PULS	(IntElement aDuration, IntElement bDuration, ModVectorElement a, ModVectorElement b)	Pulse	Returns a for aDuration frames then b for bDuration frames, then repeats this cycle	✔	✔	✔	✔	✔
SPOS	(VectorElement pos)	Set Position	Overrides the particle's position as pos	✔	✔	✔	✔	✔
SWRL	(VectorElement helixPoint, VectorElement curveBinormal, RealElement targetRadius, RealElement tangentialVelocity)	SWRL	Maintains a curve differential along a helix using a system derived from the Frenet–Serret formulas. The helical axis crosses through helixPoint in local space, oriented along curveBinormal. The particle's velocity is continuously updated to maintain targetRadius from the helical axis, while traveling along the curve tangent at tangentialVelocity units/frame.	✔	✔	✔	✔	✔
WIND	(VectorElement windVelocity, RealElement factor)	Wind	Integrates a cumulative force outside the particle's local reference; computed as ((windVelocity - particleVelocity) * factor) units/frame2	✔	✔	✔	✔	✔

Color Elements

FourCC	Parameters	Description	Notes	MP1	MP2	MP3	DKCR	DKCTF
CFDE	(ColorElement a, ColorElement b, RealElement startFrame, RealElement endFrame)	Fade End	Returns a before startFrame and b after endFrame, otherwise a linear-interpolation from a to b in-between.	✔	✔	✔	✔	✔
CHAN	(ColorElement a, ColorElement b, IntElement thresholdFrame)	Time Chain	Returns a when current frame index is less-than thresholdFrame, otherwise b	✔	✔	✔	✔	✔
CNST	(RealElement r, RealElement g, RealElement b, RealElement a)	Constant	Composes a color from 4 float components. If all 4 components are Constant, then the internal representation is an optimized CColor data-structure.	✔	✔	✔	✔	✔
FADE	(ColorElement a, ColorElement b, RealElement endFrame)	Fade	Returns b after endFrame, otherwise a linear-interpolation from a to b between frame 0 and endFrame.	✔	✔	✔	✔	✔
KEYE	(KeyframeEmitterData data)	Keyframe Emitter	List of synchronized animation keys	✔	✔	✔	✔	✔
KEYP	(KeyframeEmitterData data)	Keyframe Emitter	List of percentage-tweened animation keys	✔	✔	✔	✔	✔
PCOL	()	Particle Color	Accesses the color of the current particle instance	✔	✔	✔	✔	✔
PULS	(IntElement aDuration, IntElement bDuration, ColorElement a, ColorElement b)	Pulse	Returns a for aDuration frames then b for bDuration frames, then repeats this cycle	✔	✔	✔	✔	✔

UV Elements

Example of an ATEX map used in the closing cinematic (spoilers)

FourCC	Parameters	Description	Notes	MP1	MP2	MP3	DKCR	DKCTF
CNST	(TXTR tex)	Constant	References tex for sampling using constant UV rectangle points (0,0) (1,1)	✔	✔	✔	✔	✔
ATEX	(TXTR tex, IntElement tileW, IntElement tileH, IntElement strideW, IntElement strideH, IntElement cycleFrames, bool loop)	Animated Texture	References tex for sampling using UV tiles scanned left-to-right, top-to-bottom as individual frames of animation. The UV coordinates are scaled and offset using the tile and stride parameters in texels. All tiles of the image are played over the course of cycleFrames. If loop is set, the tiles repeat, otherwise lingers on the final tile.	✔	✔	✔	✔	✔

Emitter Elements

FourCC	Parameters	Description	Notes	MP1	MP2	MP3	DKCR	DKCTF
SETR/SEMR	(VectorElement position, VectorElement velocity)	Simple Emitter	Directly initializes new particle instances with position and velocity arguments. The only difference with SETR is the position argument is tagged with ILOC and velocity is tagged with IVEC, theoretically making the parameters optional or re-orderable.	✔	✔	✔	✔	✔
SPHE	(VectorElement sphereOrigin, RealElement sphereRadius, RealElement velocity)	Sphere	Randomly initializes new particle positions along the surface of a sphere defined by sphereOrigin and sphereRadius. The resulting velocity vector is computed from the sphereOrigin to this random point, with the magnitude set as velocity.	✔	✔	✔	✔	✔
ASPH	(VectorElement sphereOrigin, RealElement sphereRadius, RealElement velocity, RealElement angleXBias, RealElement angleYBias, RealElement angleXRange, RealElement angleYRange)	Angle Sphere	Randomly initializes new particle positions along the surface of an angular sphere-section defined by sphereOrigin and sphereRadius. The angular section is based on position (0,0,1) rotated about the X/Y axis, randomized within angleXRange and angleYRange centered around angleXBias and angleYBias. The resulting velocity vector is computed from the sphereOrigin to this random point, with the magnitude set as velocity.	✔	✔	✔	✔	✔

Keyframe Emitter Template

KEYE and KEYP elements statically encode a list of key values for all element types (except Mod Vector, UV and Emitter elements). T represents the type being encoded.

Data Type	Description	Notes
u32	Percentage-Tweening Flag	If non-zero, this is a KEYP and there are exactly 101 keys in the list; all of these keys are linearly-interpolated over the lifetime of the particle instance (however long that may be)
u32	Unknown	Not used by GetValue
u8	Loop Flag	If non-zero, the key values are looped between loopStart and loopEnd indices (does not apply to KEYP)
u8	Unknown	Not used by GetValue
u32	Loop End	Final key index in the loop
u32	Loop Start	First key index in the loop
u32	Key Count	Count of keys encoded in the list
T[keyCount]	Keys	The actual key values themselves