官术网_书友最值得收藏!

Exploring the physics system

SpriteKit simulates physics with physics bodies. We attach physics bodies to all the nodes that need physics computations. We will set up a quick example before exploring all of the details.

Dropping like flies

Our bees need to be part of the physics simulation, so we will add physics bodies to their nodes. Open your Bee.swift file and locate the spawn function. Add the following code at the bottom of the function:

// Attach a physics body, shaped like a circle
// and sized roughly to our bee.
self.physicsBody = SKPhysicsBody(circleOfRadius: size.width / 2)

It is that easy to add a node to the physics simulation. Run the project. You will see our three Bee instances drop off the screen. They are now subject to gravity, which is on by default.

Solidifying the ground

We want the ground to catch falling game objects. We can give the ground its own physics body so the physics simulation can stop the bees from falling through it. Open your Ground.swift file, locate the spawn function, and then add this code at the bottom of the function:

// Draw an edge physics body along the top of the ground node.
// Note: physics body positions are relative to their nodes.
// The top left of the node is X: 0, Y: 0, given our anchor point.
// The top right of the node is X: size.width, Y: 0
let pointTopRight = CGPoint(x: size.width, y: 0)
self.physicsBody = SKPhysicsBody(edgeFromPoint: CGPointZero, 
    toPoint: pointTopRight)

Run the project. The bees will now quickly drop and then stop once they collide with the ground. Notice how bees that fall farther bounce more energetically. After the bees land, your simulator will look like this:

主站蜘蛛池模板: 葫芦岛市| 彭山县| 会昌县| 松潘县| 苏尼特右旗| 柏乡县| 南溪县| 麟游县| 陆川县| 甘泉县| 榆社县| 射洪县| 贵德县| 都江堰市| 怀远县| 新竹市| 兰坪| 崇明县| 茌平县| 大方县| 汨罗市| 林芝县| 花莲市| 丽江市| 大理市| 铜川市| 登封市| 西林县| 仪征市| 视频| 襄汾县| 兴国县| 高邑县| 新兴县| 额济纳旗| 芒康县| 巢湖市| 台南市| 连城县| 辛集市| 台州市|