Unreal Engine: Visual and Audio Effects

While last week covered animation and animation montages, this week was juice: the legacy Cascade particle system and its successor Niagara, sounds, sound cues and MetaSounds, camera shake, post-process effects, and force feedback.

Updates were committed to sawnoff-studios/niagara-system-demo as I followed along – notes below.

Cascade (Legacy Particle System)

• Add via the Add button → Add Feature or Content Pack → Miscellaneous → Cascade Particle System (Legacy)
• Open a particle effect and enable/disable modules via checkboxes
• Worth learning a little anyway: concepts carry across to Niagara

Cascade to Niagara Converter

• The plugin can convert Cascade systems, but results are generally error-prone
• Warnings on opening (e.g. scale being off); it can attempt to automatically fix issues

Niagara Emitters

• Emitters are like blueprint nodes – modular, reusable components – and unlike Cascade, you can access them individually
• Create an Emitter and pick a template to start from

Selecting and configuring properties:

• Click a property → Details panel on the right
• Sprite Attributes → Sprite-based renderer → Sprite Material: sprite particles face toward the camera by default
• Add new properties/modules via the plus icon
• Delete with the DEL key

Useful modules:

• Add Velocity → Velocity Mode → Linear: sets velocity in X/Y/Z; the small dropdown changes the velocity type
• Particle State is on by default – drag the lifetime minimum/maximum to change when effects kick in
• Scale Color transitions from one color to another – the dropdown can make a vector from a Linear Color RGB
• Color from Curve: double-click the top pin for the color picker, double-click the curve to add pins – top is color, bottom is alpha

Niagara Systems

• Niagara Emitters can’t be placed in the world directly – they must live inside a Niagara System
• Right-click an Emitter → Create Niagara System
• Systems can expose user parameters
• Ctrl+D duplicates without affecting the original Emitter
• Emitters can be exported as assets via right-click

Spawning Effects

Blueprint:

• Spawn System at Location / Attached for Niagara
• Spawn Emitter at Location only offers Cascade particles – a legacy relic

C++:

• Add "Niagara" to Build.cs, then UNiagaraFunctionLibrary::SpawnSystemAtLocation()
• Gotcha: spawning at an actor’s location fires from the base of the mesh, because that’s where the pivot is – get the object’s size, halve it, and offset the spawn position

Audio

• Import as usual, but effectively only .wav/.ogg are supported (no .mp3)
• Basic playback and property editing available on import

Sound Classes:

• Configure in Project Settings → Engine → Audio → Default Classes
• Group sounds into classes → per-class volume sliders (e.g. a Master group)
• Make sure effects get added to the right class – you rarely play a raw sound wave directly

Sound Cues (UE4):

• Right-click a wave file → Create Cue, then add effects on the right
• Select multiple waves → Create Multiple Cues – the cue randomizes between them
• Being slowly phased out (see MetaSounds)

MetaSounds:

• For fully randomized sound effects and music generation
• Right-click → MetaSound Source
• Gotcha: wiring On Play → Output results in the audio cutting off instantly - hook up On Finished → Output to make it play out
• Pitch shift via semitones, driven by a Random (Float) node; hooking it via the Next pin randomizes pitch on every play
• Ctrl+D a MetaSound and swap the effect to create variants
• Generators (e.g. Square wave) can synthesize tones directly – Change Type → Trivial

Playing sounds in Blueprint:

• Play Sound 2D – constant volume regardless of listener position (UI, ambient)
• Play Sound at Location - attenuates from a world position
• Sound dragging on too long? Spawn Sound at Location instead, promote the return value to a variable (an Audio Component reference like FuseRef), and call Stop on it when needed

C++:

• A USoundBase* reference in the header, then:

UGameplayStatics::PlaySoundAtLocation(this, ExplosionSound, GetActorLocation());

Sound Attenuation:

• Create a Sound Attenuation asset (right side of the sound’s Details panel)
• Override attenuation → set Inner Radius and Falloff Distance
• One attenuation asset can serve multiple sound effects

Camera Shake

• Create CS_Explosion as a Blueprint with parent DefaultCameraShakeBase – a data-only Blueprint using the Root Shake Pattern
• In the bomb Blueprint, call Play World Camera Shake with CS_Explosion

Particle Effects

• E.g. NE_Explosion with a Mesh Renderer emitting dust particles (rather than sprites)

Post Process

• Add a PostProcessVolume via the Outliner’s Add button → Visual Effects
• Set properties (bloom, exposure, etc.) in the Details panel
• Infinite Extent (Unbound) makes it override the global post process
• Multiple volumes are ordered by Priority

Force Feedback

• Add gamepad support early if you plan to use it – input actions and mappings for the pad first
• Create the effect: Input → Force Feedback Effect (or Miscellaneous → Haptic Feedback for VR) → FF_Explosion
• Build curves and offsets the same way as timelines
• Trigger via Client Play Force Feedback, with Get Player Controller as the target

Notes on things that stood out

The week’s running theme was old and new living side by side: Cascade→Niagara, Sound Cues→MetaSounds, each pair with a converter that half-works and a lesson in why the old system’s concepts still matter.

The most practical takeaway was the pivot-point spawn gotcha - effects appearing at an actor’s feet is a classic “works on my machine” bug - and the On Finished → Output trap in MetaSounds, which produces a silently truncated sound with no error.