SWHC (File Format)

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

The SWHC particle script format is used to build swoosh effects in the Metroid Prime series. Swooshes are characterized as dynamically-generated triangles "brushed" into space.

Each swoosh system emits particle instances once per frame, connecting each new instance with the previous instance. The system will not render until it has a history of at least 2 swoosh particles (2 frames of updates). Swoosh cross-sections may form simple planes through space (SIDE==2) or extruded prism shapes (SIDE>=3).

To smooth out intra-frame geometry, vertices connecting particle instances may be calculated using tricubic interpolation. SPLN defines the number of subdivisions with which to perform interpolation.

Properties

Particle generator properties are assembled into a particle script file tagged with SWSH. Any of the following properties are loaded into a description class for constructing an arbitrary number of particle generators.

FourCC	Type	Description	Scope	Notes	MP1	MP2	MP3	DKCR	DKCTF
PSLT	IntElement	Particle System Lifetime	System Init	Count of frames to emit new particle instances	✔	✖	✖	✖	✖
TIME	RealElement	Time Multiplier	Pre Particles Update	Factor that defines number of evaluation frames per real frame	✔	✖	✖	✖	✖
LRAD	RealElement	Left Radius	Particle Update	Radius of swoosh cross-section's left side	✔	✖	✖	✖	✖
RRAD	RealElement	Right Radius	Particle Update	Radius of swoosh cross-section's right side	✔	✖	✖	✖	✖
LENG	IntElement	Length	System Init	Maximum history of swoosh sections to retain (must be at least 2)	✔	✖	✖	✖	✖
COLR	ColorElement	Color	Particle Creation and Update	Modulation color of swoosh surfaces	✔	✖	✖	✖	✖
SIDE	IntElement	Side Count	System Init	Count of swoosh cross-section sides (2 for plane, 3+ for extruded prism)	✔	✖	✖	✖	✖
IROT	FloatElement	Initial Rotation	Particle Creation	Rotation bias evaluated for new particle instances (in degrees)	✔	✖	✖	✖	✖
ROTM	FloatElement	Rotation Master	Particle Update	Rotation bias evaluated per particle instance, per frame (in degrees)	✔	✖	✖	✖	✖
POFS	VectorElement	Particle Offset	Particle Creation	Local translation bias evaluated for new particle instances	✔	✖	✖	✖	✖
IVEL	VectorElement	Initial Velocity	Particle Creation	Relative velocity evaluated for new particle instances	✔	✖	✖	✖	✖
NPOS	VectorElement	Next Position	Particle Update	Local translation bias updated per particle instance, per frame	✔	✖	✖	✖	✖
VELM	ModVectorElement	Velocity 1	Particle Update	Continuous position and velocity source of particle instances	✔	✖	✖	✖	✖
VLM2	ModVectorElement	Velocity 2	Particle Update	Second position and velocity source evaluated after VELM	✔	✖	✖	✖	✖
SPLN	IntElement	Spline Segments	System Init	Count of intra-frame faces to draw per particle connection, using tricubic spline interpolation	✔	✖	✖	✖	✖
TEXR	UVElement	Texture	System Render	Texture and UV source for swoosh surfaces	✔	✖	✖	✖	✖
TSPN	IntElement	Texture Span	System Render	Count of particle instances over which to scale UV coordinate cycle	✔	✖	✖	✖	✖
LLRD	bool	Left Radius for Right	System Init	Use LRAD value for RRAD	✔	✖	✖	✖	✖
CROS	bool	Cross	System Init	Intersect surfaces across cross-section verts, as opposed to a non-intersecting prism	✔	✖	✖	✖	✖
VLS1	bool	Local Velocity 1	System Init	Evaluate VELM in particle-local space	✔	✖	✖	✖	✖
VLS2	bool	Local Velocity 2	System Init	Evaluate VLM2 in particle-local space	✔	✖	✖	✖	✖
SROT	bool	Single Rotation	System Init	Update IROT per particle instance, per frame and ignore ROTM, otherwise once per system update	✔	✖	✖	✖	✖
WIRE	bool	Wireframe	System Init	Render surfaces as triangle wireframe	✔	✖	✖	✖	✖
TEXW	bool	Unknown	System Init	Unused	✖	✖	✖	✖	✖
AALP	bool	Additive Alpha	System Init	Draw using additive alpha blending	✔	✖	✖	✖	✖
ZBUF	bool	Z-buffer Update	System Init	Enable Z-buffer updates	✔	✖	✖	✖	✖
ORNT	bool	View Orient	System Init	Render surface facing view (2-SIDE only, no SPLN)	✔	✖	✖	✖	✖
CRND	bool	Clock Random	System Init	Use current CPU time for random seed, rather than 99	✔	✖	✖	✖	✖