VFX: particles, layering and colour

Contents

• Particles over 3D objects
• Textures
• Layering an explosion
• Colour: the sky tints your smoke
• Beams, trails and rings
• Verifying effects
• Checklist

Particles over 3D objects

Build effects from ParticleEmitter, Beam and Trail with real textures. Don't build them from Parts, spheres or ball clusters.

What happened: explosions looked "flat, terrible coloring", so they were rebuilt as shaded 3D ball-cluster puffs. The developer's reply: he wanted actual VFX, not 3D objects. The puff layer was thrown away.

• Fix flatness with particle technique (layers, ramps, opaque smoke), never with geometry.
• No Neon cylinder "rings" either. A flat shockwave particle (oriented VelocityPerpendicular or a flat ring texture) plus a glow reads better and is cheaper.
• No physics-Part debris. Use a debris flipbook emitter with gravity (Acceleration) and drag.
• Delete dead part-based effect code once it's replaced, or the next agent revives it.

Textures

• Use one licensed texture pack per project; don't mix packs (styles clash). Read the licence: some packs forbid AI training or redistribution. Never ship ripped textures from other games.
• Catalogue the pack once: file, category, flipbook grid (2x2, 4x4, 8x8), background (alpha or black) and the uploaded id. A catalogue lets an agent pick "soft opaque smoke" instead of guessing from file names.
• Black-background textures only work additively: LightEmission = 1. They can't do dark smoke.
• Flipbooks: set FlipbookLayout to the grid and FlipbookMode (OneShot for blasts, Loop for fire, Random for variety). Some flipbooks break up in their last cells; cut them with the transparency curve (fully transparent from ~80% of life).
• Upload many small textures as a batch. For UI-style sprites, a sprite sheet with ImageRectOffset is one upload instead of forty.

Layering an explosion

A good blast stacks about 8–12 emitters, each with its own job and timing:

Techniques that removed the "flat" look:

• Offset spawn shapes (a sphere shell for smoke, a disc for dust) so layers don't all come from one point.
• Random rotation (Rotation -180..180, RotSpeed -60..60).
• Staggered delays: 0, 0.01, 0.02, 0.03 s between layers.
• Size sequences that punch out fast (12% of life) then grow slowly.
• Colour sequences from hot white-yellow to orange to red-brown to grey, instead of one colour.

Colour: the sky tints your smoke

Smoke with LightInfluence 1 is shaded by the scene, which is what makes it look volumetric. But it also picks up the sky's ambient colour. Under a bright cyan sky ambient, grey smoke measured about 0.75 R / 1.05 G / 1.2 B of its set colour: it rendered blue-cyan, not grey.

• Pick warm smoke colours, especially for the late (light) keys: tan and warm brown like (204,152,120), which renders as neutral grey under a cyan sky.
• Keep smoke opaque for most of its life (transparency ~0.05–0.15). A see-through puff lets even more sky colour through.
• A "white" flash may need (236,204,176) to render as warm white.
• Judge rendered pixels, not properties. Sample the colour from a screenshot under the game's real lighting.

Beams, trails and rings

• A Beam runs the image's vertical axis along its length. If the texture is a horizontal streak, upload a rotated copy.
• Tracers: a short Beam between two attachments moved per frame, or a Trail. Cap them (30/60/90 by quality).
• Projectiles: a small part or attachment with a smoke Trail plus a thruster emitter; cap them too (10/24/32).

Verifying effects

• Particles freeze in edit mode. A static edit-mode screenshot shows an emitter mid-air or nothing. Verify in a playtest.
• Burst effects need a trigger to be seen. For a showcase, one small demo script per group calls :Emit() every 2–3 s.
• Capture each effect at its peak, from the player's camera height and angle, under the game's real lighting.
• The effect should read at the game's scale. At 1/4 world scale a soldier is ~1.25 studs, so a 20-stud explosion is a nuke.

Checklist

• No Parts, spheres, Neon rings or physics debris in any effect.
• One texture pack; licence read; catalogue with grid, background and id.
• Black-background textures use LightEmission 1; smoke uses soft opaque textures with LightInfluence 1.
• Explosions are layered (flash, fire, smoke, sparks, debris, dust) with offsets, rotation and staggered delays.
• Smoke colours are warm, checked against rendered pixels under the real sky.
• Effects verified in a playtest at the player's camera, not in edit mode.