SpriteKitPhysicsTest.swift

//: Playground - noun: a place where people can play

import UIKit
import SpriteKit
import PlaygroundSupport

let sceneView = SKView(frame: CGRect(x: 0, y: 0, width: 480, height: 320))

let scene = SKScene(size: CGSize(width: 480, height: 320))
scene.physicsWorld.gravity = .zero
scene.physicsBody = SKPhysicsBody(edgeLoopFrom: scene.frame)

sceneView.showsFPS = true
sceneView.showsPhysics = true
sceneView.presentScene(scene)
PlaygroundPage.current.liveView = sceneView

let square = SKSpriteNode(imageNamed: "square")
square.name = "square"
square.position = CGPoint(x: scene.size.width * 0.25,
                          y: scene.size.height * 0.5)

let circle = SKSpriteNode(imageNamed: "circle")
circle.name = "shape"
circle.position = CGPoint(x: scene.size.width * 0.5,
                          y: scene.size.height * 0.5)

let triangle = SKSpriteNode(imageNamed: "triangle")
triangle.name = "shape"
triangle.position = CGPoint(x: scene.size.width * 0.75,
                          y: scene.size.height * 0.5)

scene.addChild(square)
scene.addChild(circle)
scene.addChild(triangle)

square.physicsBody = SKPhysicsBody(rectangleOf: square.frame.size)
circle.physicsBody = SKPhysicsBody(circleOfRadius: circle.size.width / 2)
circle.physicsBody?.isDynamic = false
circle.run(
    SKAction.repeatForever(
        SKAction.move(by: CGVector(dx: -2, dy: -2), duration: 0.1)
    )
)

var trianglePath = CGMutablePath()
trianglePath.move(to: CGPoint(x: -triangle.size.width / 2,
                              y: -triangle.size.height / 2))
trianglePath.addLine(to: CGPoint(x: triangle.size.width / 2,
                                 y: -triangle.size.height / 2))
trianglePath.addLine(to: CGPoint(x: 0,
                                 y: triangle.size.height / 2))
trianglePath.addLine(to: CGPoint(x: -triangle.size.width / 2,
                                 y: -triangle.size.height / 2))
triangle.physicsBody = SKPhysicsBody(polygonFrom: trianglePath)


let l = SKSpriteNode(imageNamed: "L")
l.name = "shape"
l.position = CGPoint(x: scene.size.width * 0.5,
                     y: scene.size.height * 0.75)
l.physicsBody = SKPhysicsBody(texture: l.texture!, size: l.size)
scene.addChild(l)

func spawnSand() {
    let sand = SKSpriteNode(imageNamed: "sand")
    sand.position = CGPoint(
        x: random(min: 0.0, max: scene.size.width),
        y: scene.size.height - sand.size.height)
    sand.physicsBody = SKPhysicsBody(circleOfRadius: sand.size.width/2)
    sand.name = "sand"
    sand.physicsBody?.restitution = 0.0 // default 0.2
    sand.physicsBody?.density = 20.0    // default 1.0
    scene.addChild(sand)
}

func shake() {
    scene.enumerateChildNodes(withName: "sand") { node, stopPointer in
        node.physicsBody?.applyImpulse(
            CGVector(dx: 0,
                     dy: random(min: 20, max: 40))
        )
    }
    scene.enumerateChildNodes(withName: "shape") { node, stopPointer in
        node.physicsBody?.applyImpulse(
            CGVector(dx: random(min: 20, max: 60),
                     dy: random(min: 20, max: 60))
        )
    }
}

delay(seconds: 1) {
    scene.physicsWorld.gravity = CGVector(dx: 0, dy: -9.8)
    scene.run(
        SKAction.repeatForever(
            SKAction.sequence([
                SKAction.run(spawnSand),
                SKAction.wait(forDuration: 0.1)
                ])
        )
    )
    delay(seconds: 5, completion: shake)
}