import { Point } from '@pixi/math' ; import { Particle } from '../Particle' ; import { rotatePoint , scaleBy , length } from '../ParticleUtils' ; import { IEmitterBehavior , BehaviorOrder } from './Behaviors' ; import { BehaviorEditorConfig } from './editor/Types' ; /**
 * A Movement behavior that handles movement by applying a constant acceleration to all particles.
 *
 * Example configuration:
 * ```javascript
 * {
 *     "type": "moveAcceleration",
 *     "config": {
 *          "accel": {
 *               "x": 0,
 *               "y": 2000
 *          },
 *          "minStart": 600,
 *          "maxStart": 600,
 *          "rotate": true
 *     }
 *}
 * ```
 */ export class AccelerationBehavior implements IEmitterBehavior { public static type = 'moveAcceleration' ; public static editorConfig : BehaviorEditorConfig = null ; public order = BehaviorOrder . Late ; private minStart : number ; private maxStart : number ; private accel : { x : number ; y : number ; } ; private rotate : boolean ; private maxSpeed : number ; constructor ( config ) { this . minStart = config . minStart ; this . maxStart = config . maxStart ; this . accel = config . accel ; this . rotate = ! ! config . rotate ; this . maxSpeed = config . maxSpeed ?? 0 ; } initParticles ( first ) { let next = first ; while ( next ) { const speed = ( Math . random ( ) * ( this . maxStart - this . minStart ) ) + this . minStart ; if ( ! next . config . velocity ) { next . config . velocity = new Point ( speed , 0 ) ; } else { ( next . config . velocity as Point ) . set ( speed , 0 ) ; } rotatePoint ( next . rotation , next . config . velocity ) ; next = next . next ; } } updateParticle ( particle , deltaSec ) { const vel = particle . config . velocity ; const oldVX = vel . x ; const oldVY = vel . y ; vel . x += this . accel . x * deltaSec ; vel . y += this . accel . y * deltaSec ; if ( this . maxSpeed ) { const currentSpeed = length ( vel ) ; if ( currentSpeed > this . maxSpeed ) { scaleBy ( vel , this . maxSpeed / currentSpeed ) ; } } particle . x += ( oldVX + vel . x ) / 2 * deltaSec ; particle . y += ( oldVY + vel . y ) / 2 * deltaSec ; if ( this . rotate ) { particle . rotation = Math . atan2 ( vel . y , vel . x ) ; } } }