- Swift Game Development(Third Edition)
- Siddharth Shekar Stephen Haney
- 305字
- 2021-07-16 17:37:45
Physics bodies and gravity
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 init
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 two 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 that the physics simulation can stop the bees from falling through it. Open your Ground.swift
file, locate the createChildren
function, and 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 pointTopLeft = CGPoint(x: 0, y: 0) let pointTopRight = CGPoint(x: size.width, y: 0) self.physicsBody = SKPhysicsBody(edgeFrom: pointTopLeft, to: pointTopRight)
Run the project. The bees will now quickly drop and then stop once they collide with the ground. After the bees have landed, your simulator will look like the following screenshot:

Note
Checkpoint 3-A
The code up to this point is available in this chapter's code resources.
- 面向青少年的博物館教育(上下卷)
- 文件、信息商業(yè)化服務(wù)機(jī)構(gòu)建設(shè)研究
- 新時(shí)代檔案工作新思維
- 醫(yī)學(xué)文獻(xiàn)管理
- Learning Robotics using Python
- 探索與實(shí)踐:博物館與口述歷史
- 云環(huán)境下我國(guó)綜合數(shù)字檔案館建設(shè)模式研究
- 守望與思索:人文清華講壇實(shí)錄III
- 魯迅輯校古籍考
- 圖書館服務(wù)管理內(nèi)化:概念、過(guò)程及整合因素
- 圖書館學(xué)散論:科學(xué)網(wǎng)圖謀博客精粹
- 黨校圖書館轉(zhuǎn)型發(fā)展實(shí)踐研究
- 中國(guó)人民大學(xué)復(fù)印報(bào)刊資料轉(zhuǎn)載指數(shù)排名研究報(bào)告2017
- 高校圖書館學(xué)科服務(wù)研究
- 梁思成林徽因影像與手稿珍集