使用Rust制作康威生命游戏的实现代码
目录
- 前言
- 安装准备
- 初始项目
- Cargo.toml
- 初始web项目
- 游戏规则
- 游戏设计
- Rust实现
- 测试
- 调试
前言
之前学了几遍,后来忘记了,通过制作该游戏再复习复习。
安装准备
- wasm-pack : https://rustwasm.github.io/wasm-pack/installer/
- cargo-generate:
cargo install cargo-generate
初始项目
初始rust项目
使用wasm的项目模板:
cargo generate --git https://github.com/rustwasm/wasm-pack-template
- 提示输入project名wasm-game-of-life
- 在lib.rs中可以看见如下内容:
mod utils; use wasm_bindgen::prelude::*; // When the `wee_alloc` feature is enabled, use `wee_alloc` as the global // allocator. #[cfg(feature = "wee_alloc")] #[global_allocator] static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT; #[wasm_bindgen] extern { fn alert(s: &str); } #[wasm_bindgen] pub fn greet() { alert("Hello, wasm-game-of-life!"); }
- 它导入 window.alertJavaScript 函数,并导出greet的Rust 函数。
Cargo.toml
- Cargo.toml预置了[lib]和[dependencies]。解释一下crate-type中f=“https://users.rust-lang.org/t/what-is-the-difference-between-dylib-and-cdylib/28847”>cdylib和rlib的作用:
- cdylib:顾名思义,是C的动态链接库的意思,可以被C和C++程序链接使用
- rlib:Rust静态链接库,用于静态连接其他crates
- 依赖中使用的:
- wasm-bindgen可以将Rust编写的函数和结构体暴露到JS中或者把JS的方法引入到Rust中使用
- console_error_panic_hook提供了Wasm输出Rust Panic的能力
- wee_alloc是一个轻量的Wasm内存分配器,但是会比默认分配器慢一些。
初始web项目
npm init wasm-app www
- 看到生成的pkg.json:
{ "name": "create-wasm-app", "version": "0.1.0", "description": "create an app to consume rust-generated wasm packages", "main": "index.js", "bin": { "create-wasm-app": ".bin/create-wasm-app.js" }, "scripts": { "build": "webpack --config webpack.config.js", "start": "webpack-dev-server" },
- html里导入boostrap.js,boostrap.js里导入index.js。 index.js里面导入了其已经制作好的一个包:
import * as wasm from "hello-wasm-pack"; wasm.greet();
- 我们修改pkg.json,导入自己的包(该包需要使用
wasm-pack build
生成)
"wasm-game-of-life": "file:../pkg"
- 将index.js更换下:
import * as wasm from "wasm-game-of-life"; wasm.greet();
- 使用npm i 安装依赖。
- 使用npm run start 启动页面,打开http://localhost:8080/即可看见alert。
游戏规则
- Conway’s Game of Life是英国数学家约翰·何顿·康威在1970年发明的放置类无玩家参与的游戏
- 百度百科
- https://baike.baidu.com/item/%E5%BA%B7%E5%A8%81%E7%94%9F%E5%91%BD%E6%B8%B8%E6%88%8F/22668799?fr=aladdin主要规则如下:
- 1、任何少于两个活邻居的活细胞都会死亡,就像是由于人口不足造成的。
- 2、任何有两三个活邻居的活细胞都可以活到下一代。
- 3、任何有超过三个活邻居的活细胞都会死亡,就像人口过剩一样。
- 4、任何只有三个活邻居的死细胞都会变成活细胞,就像通过繁殖一样。
游戏设计
- 为啥说这个呢,因为2种语言去做这个东西会考虑哪个东西在哪个里面去实现。
- rust推荐大型、长寿命的数据结构被实现为 Rust 类型,这些类型存在于 WebAssembly 线性内存中,并作为不透明的句柄暴露给 JavaScript。JavaScript 调用导出的 WebAssembly 函数,这些函数采用这些不透明的句柄、转换它们的数据、执行繁重的计算、查询数据并最终返回一个可复制的结果。通过只返回计算结果,我们避免了在 JavaScript 垃圾收集堆和 WebAssembly 线性内存之间来回复制和/或序列化所有内容。
- 这个游戏中,会将universe的显示效果暴露给js渲染,其余计算在rust去实现。
- 由于宇宙是n*n的,所以我们可以用一维数组去表示它,比如4x4的宇宙就是这样:
- 将数组每个row换下来就是需要的4x4的显示了。因为这种表现形式,所以我们需要对数组索引和行列进行转换,公式为:
index(row, column, universe) = row * width(universe) + column
- 就比如我要知道4行4列是索引几,根据公式就是3*4 + 3。
- 每个单元格有一个字节,其中0表示死亡,1表示存活。
Rust实现
首先我们需要定义每个单元格:
#[wasm_bindgen] #[repr(u8)] #[derive(Clone, Copy, Debug, PartialEq, Eq)] pub enum Cell { Dead = 0, Alive = 1, }
枚举类型,0是死亡,1是存活,#[repr(u8)]
表示一个单元格1字节。复习下:
长度 | 有符号 | 无符号 |
---|---|---|
8-bit | i8 | u8 |
16-bit | i16 | u16 |
32-bit | i32 | u32 |
64-bit | i64 | u64 |
128-bit | i128 | u128 |
arch | isize | usize |
接下来定义宇宙:
#[wasm_bindgen] pub struct Universe { width: u32, height: u32, cells: Vec<Cell>, }
- 宇宙是长宽和一个动态数组。
- 我们对universe实现一些方法便于操作:
#[wasm_bindgen] impl Universe { fn get_index(&self, row: u32, column: u32) -> usize { (row * self.width + column) as usize } }
- get_index就是上面公式做索引。
- 从前面游戏规则上可知,我们需要对每个单元格求出周围格子的存活数量,于是加上这个函数:
fn live_neighbor_count(&self, row: u32, column: u32) -> u8 { let mut count = 0; for delta_row in [self.height - 1, 0, 1].iter().cloned() { for delta_col in [self.width - 1, 0, 1].iter().cloned() { if delta_row == 0 && delta_col == 0 { continue; } let neighbor_row = (row + delta_row) % self.height; let neighbor_col = (column + delta_col) % self.width; println!("{},{}-s-", neighbor_row, neighbor_col); let idx = self.get_index(neighbor_row, neighbor_col); count += self.cells[idx] as u8; } } count }
- 解释下这个函数,其中迭代height-1 , 0 , 1 以及 width-1,0,1就是求传入row与col的周围的格子里存活数量。当迭代到0,0时,这个格子代表其自身,所以直接忽略。
- 比如64x64的宇宙,查询2,2周围的格子就是:
1,1
1,2
1,3
2,1
2,3
3,1
3,2
3,3
- 边界处理靠取余,这样也能避免无符号向下溢出,所以0,0的周围格子就是:
63,63
63,0-
63,1
0,63
0,1
1,63
1,0
1,1
- 再从当前宇宙中获取格子的状态,如果是0,那么加上也不会增加,这样最终返回的就是周围格子的存活数量了。
- 下面根据规则迭代每个细胞状态,暴露出来:
pub fn tick(&mut self) { let mut next = self.cells.clone(); for row in 0..self.height { for col in 0..self.width { let idx = self.get_index(row, col); let cell = self.cells[idx]; let live_neighbors = self.live_neighbor_count(row, col); let next_cell = match (cell, live_neighbors) { // Rule 1: Any live cell with fewer than two live neighbours // dies, as if caused by underpopulation. (Cell::Alive, x) if x < 2 => Cell::Dead, // Rule 2: Any live cell with two or three live neighbours // lives on to the next generation. (Cell::Alive, 2) | (Cell::Alive, 3) => Cell::Alive, // Rule 3: Any live cell with more than three live // neighbours dies, as if by overpopulation. (Cell::Alive, x) if x > 3 => Cell::Dead, // Rule 4: Any dead cell with exactly three live neighbours // becomes a live cell, as if by reproduction. (Cell::Dead, 3) => Cell::Alive, // All other cells remain in the same state. (otherwise, _) => otherwise, }; next[idx] = next_cell; } } self.cells = next; }
- 最后需要对universe实现输出功能,先将其输出成文本,实现display方法:
impl fmt::Display for Universe { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { for line in self.cells.as_slice().chunks(self.width as usize) { for &cell in line { let symbol = if cell == Cell::Dead { '' } else { '' }; write!(f, "{}", symbol)?; } write!(f, "\n")?; } Ok(()) } }
最后进行暴露初始化和渲染方法:
pub fn new() -> Universe { let width = 64; let height = 64; let cells = (0..width * height) .map(|i| { if i % 2 == 0 || i % 7 == 0 { Cell::Alive } else { Cell::Dead } }) .collect(); Universe { width, height, cells, } } pub fn render(&self) -> String { self.to_string() }
- 使用wasm-pack build打包
- 使用js渲染,修改html加入标签:
<pre id="game-of-life-canvas"></pre>
index.js加入下面代码:
import { Universe } from "wasm-game-of-life"; const pre = document.getElementById("game-of-life-canvas"); const universe = Universe.new(); const renderLoop = () => { pre.textContent = universe.render(); universe.tick(); requestAnimationFrame(renderLoop); }; renderLoop();
- 即可看见效果。
- 下面使用canvas进行渲染,将universe中暴露其属性:
pub fn width(&self) -> u32 { self.width } pub fn height(&self) -> u32 { self.height } pub fn cells(&self) -> *const Cell { self.cells.as_ptr() }
- html中替换为canvas:
<canvas id="game-of-life-canvas"></canvas>
修改js:
import { Universe, Cell } from "wasm-game-of-life"; import { memory } from "wasm-game-of-life/wasm_game_of_life_bg"; const CELL_SIZE = 5; // px const GRID_COLOR = "#CCCCCC"; const DEAD_COLOR = "#FFFFFF"; const ALIVE_COLOR = "#000000"; const universe = Universe.new(); const width = universe.width(); const height = universe.height(); // Give the canvas room for all of our cells and a 1px border // around each of them. const canvas = document.getElementById("game-of-life-canvas"); canvas.height = (CELL_SIZE + 1) * height + 1; canvas.width = (CELL_SIZE + 1) * width + 1; const ctx = canvas.getContext("2d"); const drawGrid = () => { ctx.beginPath(); ctx.strokeStyle = GRID_COLOR; // Vertical lines. for (let i = 0; i <= width; i++) { ctx.moveTo(i * (CELL_SIZE + 1) + 1, 0); ctx.lineTo(i * (CELL_SIZE + 1) + 1, (CELL_SIZE + 1) * height + 1); } // Horizontal lines. for (let j = 0; j <= height; j++) { ctx.moveTo(0, j * (CELL_SIZE + 1) + 1); ctx.lineTo((CELL_SIZE + 1) * width + 1, j * (CELL_SIZE + 1) + 1); } ctx.stroke(); }; const getIndex = (row, column) => { return row * width + column; }; const drawCells = () => { const cellsPtr = universe.cells(); const cells = new Uint8Array(memory.buffer, cellsPtr, width * height); ctx.beginPath(); for (let row = 0; row < height; row++) { for (let col = 0; col < width; col++) { const idx = getIndex(row, col); ctx.fillStyle = cells[idx] === Cell.Dead ? DEAD_COLOR : ALIVE_COLOR; ctx.fillRect( col * (CELL_SIZE + 1) + 1, row * (CELL_SIZE + 1) + 1, CELL_SIZE, CELL_SIZE ); } } ctx.stroke(); }; const renderLoop = () => { universe.tick(); drawGrid(); drawCells(); requestAnimationFrame(renderLoop); }; renderLoop();
即可看见效果:
测试
- 一般代码需要写单元测试,看一下rust的测试怎么写。
- 首先,对Universe增加2个实现,可以将元组转换为universe的cell:
impl Universe { /// Get the dead and alive values of the entire universe. pub fn get_cells(&self) -> &[Cell] { &self.cells } /// Set cells to be alive in a universe by passing the row and column /// of each cell as an array. pub fn set_cells(&mut self, cells: &[(u32, u32)]) { for (row, col) in cells.iter().cloned() { let idx = self.get_index(row, col); self.cells[idx] = Cell::Alive; } } }
新增重置的方法:
/// Set the width of the universe. /// /// Resets all cells to the dead state. pub fn set_width(&mut self, width: u32) { self.width = width; self.cells = (0..width * self.height).map(|_i| Cell::Dead).collect(); } /// Set the height of the universe. /// /// Resets all cells to the dead state. pub fn set_height(&mut self, height: u32) { self.height = height; self.cells = (0..self.width * height).map(|_i| Cell::Dead).collect(); }
- 下面编写测试,测试在tests文件夹下的web.rs中。
- 增加以下代码:
#![cfg(target_arch = "wasm32")] extern crate wasm_bindgen_test; use std::assert_eq; use wasm_bindgen_test::*; extern crate wasm_game_of_life; use wasm_game_of_life::Universe; wasm_bindgen_test_configure!(run_in_browser); #[cfg(test)] pub fn input_spaceship() -> Universe { let mut universe = Universe::new(); universe.set_width(6); universe.set_height(6); universe.set_cells(&[(1, 2), (2, 3), (3, 1), (3, 2), (3, 3)]); universe } #[cfg(test)] pub fn expected_spaceship() -> Universe { let mut universe = Universe::new(); universe.set_width(6); universe.set_height(6); universe.set_cells(&[(2, 1), (2, 3), (3, 2), (3, 3), (4, 2)]); universe } #[wasm_bindgen_test] pub fn test_tick() { // Let's create a smaller Universe with a small spaceship to test! let mut input_universe = input_spaceship(); // This is what our spaceship should look like // after one tick in our universe. let expected_universe = expected_spaceship(); // Call `tick` and then see if the cells in the `Universe`s are the same. input_universe.tick(); assert_eq!(&input_universe.get_cells(), &expected_universe.get_cells()); }
- 然后使用
wasm-pack test --firefox --headless
即可运行测试结果。如果安装浏览器失败,可以使用谷歌,或者去掉无头属性,直接网页上看测试结果。
调试
- 我们知道,web上使用console.log去输出调试内容,rust的代码如何在web中调试呢?
- 这里需要安装下web-sys
[dependencies.web-sys] version = "0.3" features = [ "console", ]
- 导入外部websys,制作自定义宏:
extern crate web_sys; // A macro to provide `println!(..)`-style syntax for `console.log` logging. macro_rules! log { ( $( $t:tt )* ) => { web_sys::console::log_1(&format!( $( $t )* ).into()); } }
format宏与其他几个输出区别在于其使用write,不输出到标准输出中:
format!: write formatted text to String print!: same as format! but the text is printed to the console (io::stdout). println!: same as print! but a newline is appended. eprint!: same as format! but the text is printed to the standard error (io::stderr). eprintln!: same as eprint!but a newline is appended.
然后就可以在需要的地方console了,比如neighbours那:
let live_neighbors = self.live_neighbor_count(row, col); log!( "cell[{}, {}] is initially {:?} and has {} live neighbors", row, col, cell, live_neighbors ); let next_cell = match (cell, live_neighbors) { // Rule 1: Any live cell with fewer than two live neighbours // dies, as if caused by underpopulation. (Cell::Alive, x) if x < 2 => Cell::Dead, // Rule 2: Any live cell with two or three live neighbours // lives on to the next generation. (Cell::Alive, 2) | (Cell::Alive, 3) => Cell::Alive, // Rule 3: Any live cell with more than three live // neighbours dies, as if by overpopulation. (Cell::Alive, x) if x > 3 => Cell::Dead, // Rule 4: Any dead cell with exactly three live neighbours // becomes a live cell, as if by reproduction. (Cell::Dead, 3) => Cell::Alive, // All other cells remain in the same state. (otherwise, _) => otherwise, }; log!(" it becomes {:?}", next_cell); next[idx] = next_cell;
打开web,即可看见console的内容。
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