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[MetaballsKit] Just replace balls when size changes

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This commit is contained in:
Eryn Wells 2017-08-06 08:25:13 -07:00
parent 357db9a248
commit fdcf62db74
1 changed files with 19 additions and 6 deletions
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25
MetaballsKit/Metaballs.swift
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@ -43,7 +43,16 @@ public class Field {
let numberOfBallsBeforeFilter = balls.count
// Remove balls that fall outside the new bounds.
balls = balls.filter { bounds.contains($0.bounds) }
// balls = balls.filter { bounds.contains($0.bounds) }
// Scale balls to new position and size.
let scale = Float(size.width / oldValue.width)
balls = balls.map {
let r = $0.radius * scale
let p = randomPoint(forBallWithRadius: r)
let v = Vector(dx: $0.velocity.dx * scale, dy: $0.velocity.dy * scale)
return Ball(radius: r, position: p, velocity: v)
}
// Update Metal state as needed.
populateParametersBuffer()
@ -91,11 +100,7 @@ public class Field {
}
public func add(ballWithRadius radius: Float) {
let insetBounds = bounds.insetBy(dx: CGFloat(radius), dy: CGFloat(radius))
let x = Float(UInt32(insetBounds.minX) + arc4random_uniform(UInt32(insetBounds.width)))
let y = Float(UInt32(insetBounds.minY) + arc4random_uniform(UInt32(insetBounds.height)))
let position = Point(x: x, y: y)
let position = randomPoint(forBallWithRadius: radius)
let dx = Float(5 - Int(arc4random_uniform(10)))
let dy = Float(5 - Int(arc4random_uniform(10)))
@ -114,6 +119,14 @@ public class Field {
balls.removeAll(keepingCapacity: true)
}
private func randomPoint(forBallWithRadius radius: Float) -> Point {
let insetBounds = bounds.insetBy(dx: CGFloat(radius), dy: CGFloat(radius))
let x = Float(UInt32(insetBounds.minX) + arc4random_uniform(UInt32(insetBounds.width)))
let y = Float(UInt32(insetBounds.minY) + arc4random_uniform(UInt32(insetBounds.height)))
let position = Point(x: x, y: y)
return position
}
// MARK: - Metal Configuration
private var device: MTLDevice?