miracle

[akevalion]

| canvas n r s1 particles s2 s3 |

canvas := RSCanvas new.
canvas clearBackground: false.
canvas color: Color black.
n := 600.
r := 75.
s1 := NSScale linear
	domain: { 0. n };
	range: { Float pi negated. Float pi }.
s2 := NSScale linear
	domain: { r * 2. 0 };
	range: {Float twoPi. Float pi}.
s3 := NSScale linear
	domain: { r * 2. 0 };
	range: { Float pi. Float twoPi }.
	
particles := OrderedCollection new.
(0 to: n-1) do: [ :i |
	| theta p out alpha shape |
	theta := s1 scale: i.
	p := (theta cos @ theta sin) * r.
	
	out := false.
	shape := RSEllipse new
		position: p;
		size: 2.1;
		color: (Color h: i/6 * 360 / 100 s: 1 v: i % 100 / 100);
		yourself.
	shape propertyAt: #update put: [ 
		| d angle v |
		d := p distanceTo: 0@0.
		angle := p angle + (out 
			ifTrue: [ s2 scale: d ]
			ifFalse: [ s3 scale: d ]).
		v := angle cos @ angle sin .
		p := p + v.
		
		d > (r * 3 - 1) 
			ifTrue: [ out := false ]
			ifFalse: [ d < (r +1) ifTrue: [ out := true ] ].
		
		"shape color: (shape color alpha: alpha)."
		shape position: p.
		"alpha := 1."
		 ].
	particles add: shape.
	 ].
canvas addAll: particles.

canvas newAnimation
	repeat;
	onStepDo: [ :t |
		particles do: [ :p |
			(p propertyAt: #update) value ].
		 ].
canvas videoExporter
	p480;
	duration: 12 seconds;
	export