Tracers & Bolts — RCE Documentation

Overview

TracerManager is a self-contained MonoBehaviour that handles the spawning, pooling, updating, and GPU rendering of tracer and bolt visual effects. It operates independently from the reticle rendering pipeline, so tracers never interfere with reticle draw calls or category transitions.

Rendering is performed by the TracerSDF shader via a CommandBuffer submitted through RenderPipelineManager.endCameraRendering. This hook is part of the SRP core package and works identically in both URP and HDRP — no pipeline-specific assembly references or renderer features are required.

The system supports three visual types:

Type	Enum	Description
Bolt	`TracerType.Bolt`	Sci-fi energy bolt. Consistent appearance per shot, configurable perspective taper, glow, and end roundness.
Stream	`TracerType.Stream`	Continuous beam effect. Persists while firing with animated sine-wave displacement, noise modulation, and optional dual-beam rendering.
Bullet	`TracerType.Bullet`	Realistic tracer ammunition. Per-shot randomization across three sub-types (Streak, Bolt, Dot) with wobble, phosphorus-burn flicker, and sputtering.

All tracers are pooled in a fixed-size NativeArray<TracerData> (default 32, configurable up to 128) and uploaded to the GPU as a single StructuredBuffer each frame. Like the reticle system, the entire tracer pool renders in one draw call.

Origin Modes

The origin point — where tracers appear to fly in from — is controlled by TracerOriginMode:

Mode	Behavior
Fixed	All shots originate from a user-defined angle.
Scatter	Each shot comes from a completely random angle.
RandomStart	A random angle is chosen on mouse-down; all shots in that burst use it.
Animated	Origin rotates at a slow-to-medium speed with randomized direction changes.
Tempest	Aggressive arcade-style rotation with random pauses and sharp direction reversals.

Tracer Data

The tracer system uses three complementary data structures:

TracerData (GPU Struct)

TracerData is a 172-byte blittable struct that represents a single active tracer on the GPU. It contains origin/target positions, progress, color, glow, perspective parameters, wobble fields (Bullet type), and beam wave fields (Stream type). The struct is uploaded to the TracerSDF shader via a StructuredBuffer.

Key fields include:

origin / target — Start and end positions in UV space (screen-relative)
progress — Travel progress from 0 (at origin) to 1 (at target)
perspectiveScale / perspectiveDepth — Hyperbolic perspective taper for the sci-fi look of bolts narrowing as they approach center
beamAmplitude / beamFrequency / beamSpeed — Sine-wave parameters for Stream-type beam displacement
beamNoiseAmount / beamNoiseScale — Perlin noise displacement for organic beam variation (lightning effects)
impactBurnSize / impactBurnIntensity — Glowing impact point rendered where the tracer hits the target

TracerConfig (Runtime Configuration)

TracerConfig is the serializable configuration class that defines a tracer's appearance and behavior. It includes all visual parameters (color, width, length, glow, feather, taper, perspective) along with type-specific settings for beam waves, dual-beam rendering, and randomization profiles. TracerManager holds a reference to the active TracerConfig and uses it to spawn new tracer instances.

The class also provides static factory presets: DefaultLaserBolt, PlasmaBolt, ExtremeBeam, DefaultBeam, ArcBeam, DualArc, LightningBeam, and PlasmaBeam.

TracerPresetData (Saveable Preset)

TracerPresetData wraps a TracerConfig with metadata for persistence: a GUID identifier, display name, author, description, timestamps, fire rate, and a flag indicating whether the preset is a read-only default. Presets are serialized to JSON and stored as .adstracer files.

Tracer Presets

Tracer presets provide a save/load system for tracer configurations. The preset pipeline has two layers:

TracerSerializer — Handles JSON serialization and deserialization of TracerPresetData, including validation and schema versioning (currently v3). Files use the .adstracer extension.
TracerStorage — Implements ITracerStorage and manages file I/O. Resolves paths through IDataPathProvider for platform-agnostic storage. Ships with 8 built-in default presets (Default Laser, Plasma Bolt, Extreme Beam, Beam, Arc Beam, Dual Arc, Lightning, Plasma Stream) that are registered in memory and cannot be overwritten. User-created presets are stored alongside defaults in the configured tracers directory.

Both synchronous and async I/O methods are available (Save/SaveAsync, Load/LoadAsync). The last-used preset is persisted via PlayerPrefs and restored automatically when TracerManager initializes.

Preset Sharing

Because presets are plain JSON files with a .adstracer extension, they can be shared between users or distributed with your game. Default presets are immutable — users must duplicate a default before editing it.

Tracer Editor

The tracer system includes a full visual editor for designing and previewing tracer effects in real time. It consists of two panels: the Tracer Editor for property editing and the Tracer Browser for preset management.

Tracer Editor Panel

The editor panel is a draggable floating modal (position persists in PlayerPrefs) that exposes all TracerConfig properties organized into collapsible sections. Changes are reflected immediately in the viewport — fire tracers while editing to see results in real time.

Appearance Controls

Control	Description
Tracer Type	Dropdown: Bolt, Stream, or Bullet. Changes which parameter sections are visible.
Bolt Color	Primary fill color (opens the color picker).
Glow Color	Outer glow color (opens the color picker).
Width	Thickness of the tracer body.
Length	How long the tracer extends along its path.
Min Width	Minimum width when perspective taper is active. Prevents tracers from disappearing at distance.
Glow Intensity	Brightness of the outer glow halo.
Glow Size	Radius of the glow falloff.
Feather	Edge softness of the tracer body.
Taper	How much the tracer narrows along its length (tail to head).
End Roundness	Rounds the cap at each end of the tracer. 0 = flat, 1 = hemispherical.

Motion & Origin Controls

Control	Description
Origin Mode	Dropdown: Fixed, Scatter, RandomStart, Animated, Tempest. Controls where tracers appear to originate from.
Fixed Rotation	Angle in degrees (visible only when Origin Mode = Fixed).
Speed	Travel speed of the tracer from origin to target.
Fire Rate	Shots per second when auto-firing.
Perspective Depth	How much the tracer scales based on simulated depth.
Length Perspective	How much the tracer length compresses at perspective depth.

Beam Controls (Stream type only)

These controls appear in a collapsible Beam foldout when the tracer type is set to Stream:

Control	Description
Amplitude	Magnitude of the sine-wave displacement perpendicular to the beam axis.
Frequency	Number of wave cycles along the beam length.
Speed	How fast the wave pattern scrolls along the beam.
Noise Amount	Perlin noise displacement for organic, lightning-like variation.
Noise Scale	Scale of the noise pattern. Smaller = finer detail.
Converge	How much the beam converges toward the target point.
Dual Beam	Toggle: renders a second beam with offset phase for a twin-beam look.
Phase Offset	Wave phase offset between dual beams (visible when Dual Beam is on).

Bullet Randomization (Bullet type only)

These controls appear in a collapsible Sub-Type Mix foldout when the tracer type is set to Bullet:

Control	Description
Sub-Type Mix	Toggle to enable randomized bullet sub-types.
Streak / Bolt / Dot Weights	Relative probability of each sub-type per shot. Higher weight = more frequent.
Additional Variance	Extra randomization applied to width, length, and speed.
Wobble Amount	Lateral oscillation as the bullet travels.
Wobble Frequency	Speed of the wobble oscillation.
Sputter Chance	Probability (0–1) that a bullet "sputters" — flickering intermittently like a real phosphorus tracer burning out.
Flicker Amount	Intensity variation of the brightness flicker effect.

Four randomization presets are available as starting points: Realistic, Streak Heavy, Dot Heavy, and No Mix.

Impact Burn

Control	Description
Impact Burn	Toggle to enable a glowing impact point where the tracer hits.
Burn Size	Radius of the impact glow.
Burn Intensity	Brightness of the impact glow.

Tracer Browser

The tracer browser is a separate floating panel that manages the preset library:

Preset list with search/filter field
Load — Apply a preset to the active TracerManager
Edit — Open the preset in the Tracer Editor panel
New — Create a blank preset with default values
Duplicate — Clone the selected preset for customization
Delete — Remove a user-created preset (built-in defaults cannot be deleted)

Double-clicking a preset in the list immediately loads and applies it. The browser is draggable with position persisted in PlayerPrefs.

Built-in Presets

RCE ships with 8 default tracer presets: Default Laser, Plasma Bolt, Extreme Beam, Beam, Arc Beam, Dual Arc, Lightning, and Plasma Stream. These are read-only — duplicate one to use it as a starting point for customization.

Pipeline Integration

The tracer renderer hooks into Unity's Scriptable Render Pipeline via RenderPipelineManager.endCameraRendering, a callback from the UnityEngine.Rendering namespace (SRP core). This approach has several advantages:

Pipeline-agnostic — Works in URP and HDRP without any pipeline-specific code, renderer features, or custom passes.
No assembly dependencies — Unlike the reticle renderer (which uses RCERendererFeature for URP), the tracer system only depends on SRP core, which is always available.
Independent rendering — Tracer draw calls are completely separate from the reticle pipeline. Category transitions, shape animations, and GlobalFX have no impact on tracer rendering.
Single draw call — The entire tracer pool renders in one DrawProcedural call via a CommandBuffer, regardless of how many tracers are active.

The TracerSDF shader evaluates each active tracer's SDF in the fragment shader, applying perspective taper, glow, beam-wave displacement, and impact burn effects. Inactive tracers (pooled slots with isActive = 0) are skipped via early-out.

Low Quality Mode

TracerManager.LowQualityMode disables glow calculations in the shader for better performance on lower-end hardware. The tracer shapes remain crisp; only the soft glow falloff is removed.

Master Toggle

TracerManager.TracersEnabled is a master on/off switch for the entire tracer system. When set to false, all active tracers are cleared, firing stops, and the Update/Render loops early-out. The setting persists in PlayerPrefs (ADS_TracersEnabled). In the editor, the toggle appears in the tracer toolbar; disabling it dims the toolbar controls to 35% opacity as a visual indicator.

Key Files

Component	Path
TracerManager	`Assets/RCE/Runtime/Tracers/TracerManager.cs`
TracerData	`Assets/RCE/Runtime/Tracers/TracerData.cs`
TracerConfig	`Assets/RCE/Runtime/Tracers/TracerConfig.cs`
TracerPresetData	`Assets/RCE/Runtime/Tracers/TracerPresetData.cs`
TracerSerializer	`Assets/RCE/Runtime/Tracers/TracerSerializer.cs`
ITracerStorage	`Assets/RCE/Runtime/Tracers/ITracerStorage.cs` (interface)
TracerStorage	`Assets/RCE/Runtime/Tracers/TracerStorage.cs`
TracerSDF Shader	`Assets/RCE/Runtime/Shaders/TracerSDF.shader`
TracerType	`Assets/RCE/Runtime/Tracers/TracerType.cs`
TracerOriginMode	`Assets/RCE/Runtime/Tracers/TracerOriginMode.cs`
TracerRandomization	`Assets/RCE/Runtime/Tracers/TracerRandomization.cs`
TracerEditorController	`Assets/RCE/Runtime/UI/TracerEditorController.cs`
TracerBrowserController	`Assets/RCE/Runtime/UI/TracerBrowserController.cs`

What's Next

GlobalFX API — Runtime control for transient combat effects like hit markers and damage flashes
Animations — Per-layer property animations for reticle shapes
Performance — Draw call budgets, GPU cost, and profiling guidance