Create Vfx Effects

Create VFX Effects

Start from a reviewed Niagara System, particle prefab, or VFX Graph asset. The adapters provide a common spawn and cleanup interface; Unity's procedural effects are fallbacks for projects without a suitable asset.

Select The Engine

• For UE5, read <REPO_PATH>/engine_adapters/ue5/vfx/vfx_functions.py and call its Python API inside Unreal Editor.
• For Unity, read <REPO_PATH>/engine_adapters/unity3d/vfx/Runtime/A3Game_VFX.cs. Copy it under the target project's Assets/ directory before referencing the class.
• Keep engine-specific code out of host Python and model/operator modules.

For Mechanic tasks, UEClient remains the only host-side Unreal API. Use the VFX modules as references for generated engine code or in an editor-side review step; do not import them from the host Agent or bypass UEClient transport boundaries.

Reuse Templates First

1. Search the project for an effect with the right silhouette and timing. In Unity, check Assets/ and %APPDATA%/Unity/Asset Store-5.x/.
2. Tune exposed parameters, transforms, material instances, or colors on an instance. Leave the source template unchanged.
3. Pass a project-specific asset path or prefab when the documented default is not installed.
4. Fall back to Unity's procedural named functions only when no reviewed asset is available.

Do not substitute a glowing sphere or untextured white particles for smoke or fire.

UE5 Functions

• Call spawn_smoke, spawn_fire, spawn_explosion, or spawn_dust for named effects.
• Call spawn_niagara(system_path, ...) for a project-specific template.
• Call spawn_effect(kind, ...) when the category is selected dynamically.
• Call stop_effect(actor, destroy=True) to clean up a looping effect.
• For ink, frost, or cyber, call spawn_styled_effect.
• For action-attached effects, build a WorldFlexVFXBinder request with build_punch_fire_binding; run detection with Apply=false before changing an animation asset.
• Treat locations as centimeters and rotations as (pitch, yaw, roll) degrees.

Natural-effect defaults:

Stylized defaults and layer contracts:

These systems replace the stock NS_Fire renderer material with style-specific material instances and post processing. A stock system plus parameter writes is not equivalent because unsupported Niagara parameters are silent no-ops.

build_punch_fire_binding detects a high-speed hand interval and attaches a timed Niagara notify state to RightHand. Run with Apply=false, inspect the event time, duration, and scale, then apply to a copy or an approved animation asset.

Pass system_path="/Game/..." when a project installs an asset elsewhere. Missing assets raise VFXAssetNotFound.

from engine_adapters.ue5.vfx import spawn_fire, stop_effect

fire = spawn_fire(
    (120.0, -40.0, 0.0),
    scale=0.8,
    color=(1.0, 0.35, 0.05, 1.0),
)
stop_effect(fire, destroy=True)

Only set parameters exposed by the selected Niagara System. Unreal accepts writes to unused parameters, so preview one instance before applying a batch change.

Unity Functions

• Call SpawnPrefab for an existing particle prefab or compiled VFX Graph prefab.
• Call SpawnSmoke, SpawnFire, SpawnExplosion, or SpawnDust for the no-asset ParticleSystem fallback.
• For a smoke flipbook, set SmokeOptions.particleMaterial and textureSheetTiles. Use forceAlphaBlend only to correct a converted URP material; leave the package material unchanged.
• Call Stop(root, immediate) for looping smoke or fire.
• SpawnInkSmoke, SpawnFrostFire, and SpawnCyberFire are experimental fallbacks; the reviewed stylized baselines are the UE systems above.
• Treat positions and sizes as meters.
• Require the built-in com.unity.modules.particlesystem module. Add it to Packages/manifest.json when a stripped-down project has disabled it.

using A3Game.EngineAdapters;

GameObject fire = firePrefab != null
    ? A3GameVFX.SpawnPrefab(
        firePrefab, transform.position, transform.rotation, Vector3.one, transform)
    : A3GameVFX.SpawnFire(transform.position, new FireOptions {
        loop = true,
        intensity = 1.2f
    }, transform);

A3GameVFX.Stop(fire);

Validate The Result

• Preview at least one second with world ticking.
• Verify the effect reads as the requested category at gameplay camera distance.
• Verify looped effects stop and one-shot effects clean themselves up.
• Verify transparent smoke uses alpha blending and flame cores use additive or emissive rendering as appropriate.
• Use a purpose-built system instead of many full template instances for dense fields.
• Bind moving effects to the intended socket or transform and confirm coordinate units before tuning offsets.
• On UE 5.7, do not use -nullrhi for an integration test that spawns editor actors; use the normal RHI. The null-RHI Editor Scripting path can crash before Python reports an exception.
• Review stylized effects in grayscale before checking color, density, timing, gameplay scale, and attachment. Still images cannot validate motion cadence.

Require Visual Approval

Before retaining a smoke or fire preset as a baseline:

1. Render a fixed-camera video that includes startup and stable behavior.
2. Record the Niagara/prefab path, sequence, render config, fps, resolution, and duration beside the video.
3. Ask the effect owner to review silhouette, color, density, timing, and scale.
4. Keep the result pending until the owner approves it.
5. Retain the exact video and config locally as the regression baseline.

Keep review media outside the repository. Publish approved public assets through the tracking issue.