PART (File Format)
|
This file format is almost completely documented Properties beyond MP1 need to be discovered and documented |
The PART particle script format is used to configure particle effects.
Particles are the most widely-used effect in Metroid Prime, with approximately 3,500 unique scripts across the PAK archives. Each script configures a complete particle system that may draw into the scene.
The particle system is configurable to generate many visual effects:
- Flames and smoke
- Floating embers
- Water splashes/drips
- Dust and dirt in windy conditions
- Volumetric light "shimmers"
- Energy/plasma discharges
- Many others
The concept behind the particle system is quite simple: lots of view-aligned (camera-facing) quads with a texture-image are emitted, positioned, rotated, sized, colored, etc... according to the parameters in the particle script.
Particle System
The particle system ties together all procedures necessary to host an emitter and specifies the rate at which new particles should be created. New particles have a predetermined lifetime (in frames) set by the system, and the emitter initializes the position and velocity of these particles. The system continuously updates all currently-living particles that it's created. This includes updating properties like position, velocity, color, size and view-rotation.
Child Systems
Particle systems may also host child systems which are timed and positioned within the parent's reference. Not only does this include other PART systems, but SWHC and ELSC systems may be parented as well.
A good example of this is the flamethrower's system, which composes flame particles with a trailing SWHC and small cinders from a separate PART.
Line Mode
When the LINE property is activated, particles are rendered as lines rather than quads.
The usual 3D particle position is used as the trailing-point of the line, with the leading-point computed via positional-differential, scaled by other parameters. Lines sample textures diagonally as a single-texel strip, allowing for gradients to be applied via spherical or diagonal ramp-textures.
Model Mode
When the PMDL property is provided with a CMDL, particles are rendered
using that model, in addition to the quad. Alternatively, PMUS generates a quad transformed
as if it were a model (non view aligned).
Model-based particles have a whole separate suite of properties for controlling local-transformation and color. Most of the properties involving positioning and transforms from the client systems are shared from the normal quad-mode.
Many weapon effects, notably the "sphere" of the charge-beam, are accomplished using particle models.
Particle Instance
For each frame, each particle does the following primary tasks:
- Determines if particle's lifetime has finished, removing it from the scene and releasing its resources for newly created particles to use
- Invokes all velocity/position sources; advancing position 1/60th of a second
- Evaluates local transforms
- Size
- View-aligned rotation
- View-aligned offset
- Evaluates particle color (shader-multiplied with texture-image)
Emitter
Main article: Emitter Elements
Each particle-system employs a single emitter context. The system generates a specified number of particles each frame; the emitter initializing the position and velocity-vector for each.
Properties
Particle generator properties are assembled into a particle script
file tagged with GPSM. 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 |
|---|---|---|---|---|---|---|---|---|---|
| PSIV | VectorElement | System Initial Velocity | System Init | Defines the initial velocity vector which moves the entire system in local orientation (may be overridden by PSVM)
|
Demo | ✖ | ✖ | ✖ | ✖ |
| PSVM | ModVectorElement | System Velocity Mod | Post Particles Update | Mod Vector which influences the position and velocity of the entire system in local space | Demo | ✖ | ✖ | ✖ | ✖ |
| PSOV | VectorElement | System Orientation Velocity | Post Particles Update | Angular velocity (in degrees/frame) of the system's orientation | Demo | ✖ | ✖ | ✖ | ✖ |
| PSLT | IntElement | System Lifetime | System Init | Count of frames that the system generates new particles | ✔ | ✔ | ✔ | ✔ | ✔ |
| PSWT | IntElement | System Warmup Time | Warmup-Phase Update | Count of frames that the particle system virtually updates itself within one initial frame; exiting the warmup phase afterwards | ✔ | ✔ | ✔ | ✔ | ✔ |
| PSTS | RealElement | System Time Scale | Pre Particles Update | Factor that redefines the second for the system, including the rate at which the system's frame count is incremented. 1.0 is native 60-fps. 0.5 causes every other frame to skip updates, slowing down and making the motion "choppy". 2.0 causes 2 updates every frame, speeding up. | ✔ | ✔ | ✔ | ✔ | ✔ |
| POFS | VectorElement | Particle Offset | System Init, Post Particles Update | Vector that offsets all particles in world space | ✔ | ✔ | ✔ | ✔ | ✔ |
| SEED | IntElement | Random Seed | System Init | Value used to initialize the LCG seed state used within the system's update and render cycles (default 99) | ✔ | ✔ | ✔ | ✔ | ✔ |
| LENG | RealElement | Line Length | Line Particle Creation, Line Particle Update | Length of LINE particles, scaled according to FXLL
|
✔ | ✔ | ✔ | ✔ | ✔ |
| WIDT | RealElement | Line Width | Line Particle Render | Width of LINE particles in viewport pixels
|
✔ | ✔ | ✔ | ✔ | ✔ |
| MAXP | IntElement | Max Particles | System Init, Pre Particles Update | Max count of particles allowed to live at once. No new particles created if there are already this many active particles. | ✔ | ✔ | ✔ | ✔ | ✔ |
| GRTE | RealElement | Generation Rate | Pre Particles Update | Count of particles to create each frame. Remainder value is accumulated for the next update cycle. | ✔ | ✔ | ✔ | ✔ | ✔ |
| COLR | ColorElement | Color | Particle Creation, Particle Update | Color to multiply with particle's texture | ✔ | ✔ | ✔ | ✔ | ✔ |
| LTME | IntElement | Lifetime | Particle Creation | Count of frames the about-to-be-created particle lives | ✔ | ✔ | ✔ | ✔ | ✔ |
| ILOC | VectorElement | Particle Emit Location | Particle Creation | Position to initialize particle in local space (replaced by EMTR)
|
Demo | ✖ | ✖ | ✖ | ✖ |
| IVEC | VectorElement | Particle Emit Velocity | Particle Creation | Velocity to initialize particle in local space (replaced by EMTR)
|
Demo | ✖ | ✖ | ✖ | ✖ |
| EMTR | EmitterElement | Emitter | Particle Creation | Modular data source for initializing position and velocity of new particles | ✔ | ✔ | ✔ | ✔ | ✔ |
| LINE | bool | Line Mode | System Init | Render particles as lines instead of quads | ✔ | ✔ | ✔ | ✔ | ✔ |
| FXLL | bool | Line Mode | System Init | Scale leading point of line as the exact value of LENG, rather than multiplying LENG with the position-differential
|
✔ | ✔ | ✔ | ✔ | ✔ |
| AAPH | bool | Additive Alpha | System Init | Set up blending of quads and lines with source factor of GX_BL_SRCALPHA and destination factor of GX_BL_ONE as opposed to GX_BL_SRCALPHA and GX_BL_INVSRCALPHA
|
✔ | ✔ | ✔ | ✔ | ✔ |
| ZBUF | bool | Z-buffer Write | System Init | Perform rendering while writing into the z-buffer to ensure later-drawn objects don't occlude particles if positioned behind them | ✔ | ✔ | ✔ | ✔ | ✔ |
| SORT | bool | View-space Sort | System Init | Sort particles by their z-coordinate in view-space before drawing, which is essential for proper alpha blending (although mathematically unnecessary when AAPH is active)
|
✔ | ✔ | ✔ | ✔ | ✔ |
| LIT_ | bool | Unknown | System Init | Unused in demo | ✔ | ✔ | ✔ | ✔ | ✔ |
| ORNT | bool | Orient To Origin | System Init | New in retail - Simultaneously orients particle instances toward the local origin and view-point via cross-product. ROTA is used to control the width of quads in this mode, while SIZE controls the length.
|
✔ | ✔ | ✔ | ✔ | ✔ |
| RSOP | bool | Right Vector Scaled on Particle | System Init | New in retail - The right vector (particle width) is proportionally scaled with length | ✔ | ✔ | ✔ | ✔ | ✔ |
| MBLR | bool | Motion Blur | System Init | Enables sub-positional overdraw of each particle instance between its previous position and new position each frame; draw count controlled by MBSP
|
✔ | ✔ | ✔ | ✔ | ✔ |
| PMAB | bool | Model Additive Alpha | System Init | Equivalent of AAPH for models and PMUS quads
|
✔ | ✔ | ✔ | ✔ | ✔ |
| PMUS | bool | Model Unoriented Square | System Init | Draws a 1x1 quad in the XZ-plane in place of a PMDL model
|
✔ | ✔ | ✔ | ✔ | ✔ |
| PMOO | bool | Model Object Orientation | System Init | Includes client-supplied orientation in model's transform chain (after PMRT). Unlike other bool properties, this property is enabled by default
|
✔ | ✔ | ✔ | ✔ | ✔ |
| VMDn | bool | Local Vector Mod [1-4] | System Init | Applies mod vectors VELn in system local-space rather than world-space
|
✔ | ✔ | ✔ | ✔ | ✔ |
| CIND | bool | Colored Indirect Texture | System Init | When TIND is active, texels copied from the underlying framebuffer are multiplied with the texels in TEXR (rather than added). The alpha component is always multiplied.
|
✔ | ✔ | ✔ | ✔ | ✔ |
| OPTS | bool | Optional System | System Init | When a client system constructs a generator instance, it has the option to filter out child systems at any level that aren't essential to the effect. The exclusion is a mutual decision between the client and the particle description via this property. | ✔ | ✔ | ✔ | ✔ | ✔ |
| MBSP | IntElement | Motion Blur Samples | Pre Particles Update | When MBLR is active, this is the number of times the position differential of each particle instance is subdivided for overdraw
|
✔ | ✔ | ✔ | ✔ | ✔ |
| SIZE | RealElement | Particle Size | Particle Creation, Particle Update | Proportional scale (length and width) of particle quads | ✔ | ✔ | ✔ | ✔ | ✔ |
| ROTA | RealElement | Particle View-Rotation | Particle Creation, Particle Update | View-aligned counterclockwise-rotation of particle instances | ✔ | ✔ | ✔ | ✔ | ✔ |
| TEXR | UVElement | Particle Texture | Particle Creation, Particle Update | Particle texture map and UV coordinate source | ✔ | ✔ | ✔ | ✔ | ✔ |
| TIND | UVElement | Indirect Particle Texture | Particle Creation, Particle Update | Indirect texture map and UV coordinate source. Setting this property enables framebuffer->texture copies of the rectangular region behind particle instances. These texels are warped using coordinates defined in the texels of the IA texture in this property. | ✔ | ✔ | ✔ | ✔ | ✔ |
| PMDL | CMDL | Particle Model | System Init | Render particle instances using this model, in addition to quads | ✔ | ✔ | ✔ | ✔ | ✔ |
| PMOP | VectorElement | Particle Model Pre-Offset | Particle Model Render | Translate models using this vector before transforming normally | ✔ | ✔ | ✔ | ✔ | ✔ |
| PMRT | VectorElement | Particle Model Rotate | Particle Model Render | Rotate models using these euler angles (in degrees, ZYX order) | ✔ | ✔ | ✔ | ✔ | ✔ |
| PMSC | VectorElement | Particle Model Scale | Particle Model Render | Scale models using this (potentially non-proportional) vector | ✔ | ✔ | ✔ | ✔ | ✔ |
| PMCL | ColorElement | Particle Model Color | Particle Model Render | Multiply textured model color with this color | ✔ | ✔ | ✔ | ✔ | ✔ |
| VELn | ModVectorElement | Particle Mod Vectors [1-4] | Particle Update | Up to 4 mod vectors invoked (in order) on each particle instance for each frame; influencing position and velocity | ✔ | ✔ | ✔ | ✔ | ✔ |
| ICTS | PART | Counted Child System | System Init | Child particle system to spawn multiple instances of | ✔ | ✔ | ✔ | ✔ | ✔ |
| NCSY | IntElement | Counted Child System Count | System Init | Count of ICTS systems to spawn (default 1)
|
✔ | ✔ | ✔ | ✔ | ✔ |
| CSSD | IntElement | Counted Child System Frame | System Init | Frame index to spawn ICTS instances
|
✔ | ✔ | ✔ | ✔ | ✔ |
| IDTS | PART | Done Child System | System Init | Child particle system to spawn multiple instances of when parent system's lifetime finishes | ✔ | ✔ | ✔ | ✔ | ✔ |
| NDSY | IntElement | Done Child System Count | System Init | Count of IDTS systems to spawn (default 1)
|
✔ | ✔ | ✔ | ✔ | ✔ |
| IITS | PART | Interval Child System | System Init | Child particle system to spawn at regular intervals | ✔ | ✔ | ✔ | ✔ | ✔ |
| PISY | IntElement | Interval Child System Frame Interval | System Init | Frame interval to emit IITS instances
|
✔ | ✔ | ✔ | ✔ | ✔ |
| SISY | IntElement | Interval Child System Start Frame | System Init | Frame index to start emitting IITS instances
|
✔ | ✔ | ✔ | ✔ | ✔ |
| KSSM | SpawnSystemKeyframeData | Timed-Spawn Particle Systems | System Init | List of start-frame events and corresponding child systems to spawn | ✔ | ✔ | ✔ | ✔ | ✔ |
| SSWH | SWHC | Child Swoosh System | System Init | Child swoosh system parented to this system | ✔ | ✔ | ✔ | ✔ | ✔ |
| SSSD | IntElement | Child Swoosh System Start Frame | System Init | Frame index to start emitting SSWH
|
✔ | ✔ | ✔ | ✔ | ✔ |
| SSPO | VectorElement | Child Swoosh System Offset | System Init | Offset supplied as swoosh system's translation | ✔ | ✔ | ✔ | ✔ | ✔ |
| SELC | ELSC | Child Electric System | System Init | Child electric system parented to this system | ✔ | ✔ | ✔ | ✔ | ✔ |
| SESD | IntElement | Child Electric System Start Frame | System Init | Frame index to start emitting SELC
|
✔ | ✔ | ✔ | ✔ | ✔ |
| SEPO | VectorElement | Child Electric System Offset | System Init | Offset supplied as electric system's translation | ✔ | ✔ | ✔ | ✔ | ✔ |
| LTYP | IntElement | System Light Type | System Init | Type of GX light to parent to system
|
✔ | ✔ | ✔ | ✔ | ✔ |
| LCLR | ColorElement | System Light Color | Post Particles Update | Diffuse color of GX light | ✔ | ✔ | ✔ | ✔ | ✔ |
| LINT | RealElement | System Light Intensity | Post Particles Update | Light intensity factor used for calculating falloff | ✔ | ✔ | ✔ | ✔ | ✔ |
| LOFF | VectorElement | System Light Offset | Post Particles Update | Light offset (not applicable to directional lights) | ✔ | ✔ | ✔ | ✔ | ✔ |
| LDIR | VectorElement | System Light Direction | Post Particles Update | Light direction (not applicable to custom lights) | ✔ | ✔ | ✔ | ✔ | ✔ |
| LFOT | IntElement | System Light Falloff Type | System Init | Type of linear-attenuation equation to use for light
|
✔ | ✔ | ✔ | ✔ | ✔ |
| LFOR | RealElement | System Light Falloff Radius | Post Particles Update | Falloff radius for linear-attenuation (not applicable to constant) | ✔ | ✔ | ✔ | ✔ | ✔ |
| LSLA | RealElement | System Light Cutoff Angle | Post Particles Update | Cutoff angle for angular-attenuation (only applicable to spot) | ✔ | ✔ | ✔ | ✔ | ✔ |
| ADVn | RealElement | Advance Parameters [1-8] | Pre Particles Update | Parameters to compute per system update, values shared across all particle instances via PAPn real elements
|
✔ | ✔ | ✔ | ✔ | ✔ |
SpawnSystemKeyframeData
| Data Type | Description | Notes |
|---|---|---|
| u32 | Unknown | |
| u32 | Unknown | |
| u32 | End Frame | Final frame index where a system is spawned |
| u32 | Unknown | |
| u32 | List Count | |
| {u32 frame, u32 infoCount, SpawnSystemKeyframeInfo[infoCount]}[listCount] | Lists | Pairs of frame index and sequence of SpawnSystemKeyframeInfo for grouping systems that start on the same frame |
SpawnSystemKeyframeInfo
| Data Type | Description | Notes |
|---|---|---|
| PART | Child System ID | |
| u32 | Unknown | |
| u32 | Unknown | |
| u32 | Unknown |