Fx Force

Name	Type	Description
FX fx	FxState2D Required	入力 FX state です

Name	Type	Description
FX fx	FxState2D	force を追加した FX state です
フォース数 force_count	Int	現在の FX state に入っている force 数です
概要 summary	Text	この force を追加した後の FX state の短い概要です

Parameters

Name	Type	Default	Range	Description / Options
種類 kind	Enum	Gravity	—	追加する力の種類です。重力、風、ドラッグ、乱流、渦から選びます重力`Gravity` 風`Wind` ドラッグ`Drag` 乱流`Turbulence` 渦`Vortex`
ベクトルX vector_x	Float	0	-8–8 / step 0.01	重力または風ベクトルの X 成分です
ベクトルY vector_y	Float	0.25	-8–8 / step 0.01	重力または風ベクトルの Y 成分です
中心X center_x	Float	16	-512–512 / step 0.1	渦 force の中心 X 座標です
中心Y center_y	Float	16	-512–512 / step 0.1	渦 force の中心 Y 座標です
強さ strength	Float	0.8	-8–8 / step 0.01	重力または渦 force 全体の強さです
半径 radius	Float	12	0–512 / step 0.1	渦 force が効く半径です
量 amount	Float	0.25	0–8 / step 0.01	風、ドラッグ、乱流で使う量です
スケール scale	Float	8	0.1–128 / step 0.1	乱流ノイズの空間スケールです
速度 speed	Float	1	0–16 / step 0.01	乱流ノイズの時間変化の速さです

Overview

Adds a force (gravity, wind, drag, turbulence, or vortex) to FX particles. If the emitter controls how particles appear, a force controls how they move afterward. Forces create rising flames, drifting smoke, and fluttering snow.

Usage tips

Chaining forces is the standard pattern. For example, combine upward gravity with a little turbulence for fire, or weak downward gravity with wind and turbulence for snow. Two or three forces give an effect its characteristic motion.
When in doubt, add a small amount of turbulence. It quickly makes straight-line movement feel organic, but excessive amount turns the result into noise.

Related nodes

fx_emitter_2d — upstream particle emission
fx_rasterize — downstream conversion to an image
fx_domain_2d — foundation of the lane

Read this first

Fx Force changes only particle trajectories.
It does not change color or size.
The parameters shown depend on kind.

`kind`	Active parameters
`Gravity`	`vector_x`, `vector_y`, `strength`
`Wind`	`vector_x`, `vector_y`, `amount`
`Drag`	`amount`
`Turbulence`	`amount`, `scale`, `speed`
`Vortex`	`center_x`, `center_y`, `strength`, `radius`

When to use it

To make fire rise:
- use gravity upward.
To move smoke sideways:
- use wind.
To slow particles down:
- use drag.
To add wandering motion:
- use turbulence.
To create a swirl or rotation:
- use vortex.

Example

Rising flames

kind = gravity
vector = [0, -0.2]
strength = 1.0

Crosswind

kind = wind
vector = [0.2, 0]
amount = 0.8

Wandering motion

kind = turbulence
amount = 0.25
scale = 8
speed = 1

Common sequence

FxDomain2D
  -> FxEmitter2D
  -> FxForce(gravity)
  -> FxForce(turbulence)
  -> FxRasterize

The basic way to use forces is to connect several in sequence and add their effects together.

Notes

Excessive drag leaves particles almost motionless.
Excessive turbulence looks more like noise than smoke or fire.
vortex adds tangential rotation around its center; it does not pull particles inward.

Input Ports

Output Ports