蛇的移动和键盘操作

web/src/assets/scripts/AcGameObject.js

@@ -3,7 +3,7 @@ const AC_GAME_OBJECTS = [];
 export class AcGameObject {
     constructor() {
         AC_GAME_OBJECTS.push(this); // 数组添加元素
-        this.timedelta = 0;
+        this.timedelta = 0; // 注意单位是毫秒，转化为秒需要除于1000
         this.has_called_start = false;
     }
 

web/src/assets/scripts/Cell.js

@@ -0,0 +1,9 @@
+export class Cell{
+    constructor(r,c) { // 传入蛇的坐标(r,c)
+        this.r = r;
+        this.c = c;
+        this.x = c + 0.5; // 将蛇的左上角坐标(r,c)转化为画布上的圆心坐标(x,y)
+        this.y = r + 0.5;
+    }
+
+}

web/src/assets/scripts/GameMap.js

@@ -1,4 +1,5 @@
 import { AcGameObject } from "./AcGameObject"; //  导入js的export class
+import { Snake } from "./Snake";
 import { Wall } from "./Wall";
 
 export class GameMap extends AcGameObject {
@@ -10,10 +11,17 @@ export class GameMap extends AcGameObject {
         this.L = 0;
 
         this.rows = 13;
-        this.cols = 13;
+        this.cols = 14;
 
         this.inner_walls_count = 20; // 障碍物的数量(最大建议80)
         this.walls = []; // 所有障碍物组成的数组
+
+        // 创建两条蛇
+
+        this.snakes = [ // 蓝蛇和红蛇
+            new Snake({ id: 0, color: "#4876EC", r: this.rows - 2, c: 1 }, this),
+            new Snake({ id: 1, color: "#F94848", r: 1, c: this.cols - 2 }, this),
+        ];
     }
 
     check_connectivity(g, sx, sy, tx, ty) { // 判断生成的地图是否可以连通
@@ -21,7 +29,7 @@ export class GameMap extends AcGameObject {
         g[sx][sy] = true;
 
         let dx = [-1, 0, 1, 0], dy = [0, 1, 0, -1];
-        for (let i = 0; i < 4; i ++ ) {
+        for (let i = 0; i < 4; i++) {
             let x = sx + dx[i], y = sy + dy[i];
             if (!g[x][y] && this.check_connectivity(g, x, y, tx, ty))
                 return true;
@@ -32,33 +40,34 @@ export class GameMap extends AcGameObject {
 
     create_walls() { // 判断是否生成有效的地图
         const g = [];
-        for (let r = 0; r < this.rows; r ++ ) {
+        for (let r = 0; r < this.rows; r++) {
             g[r] = [];
-            for (let c = 0; c < this.cols; c ++ ) {
+            for (let c = 0; c < this.cols; c++) {
                 g[r][c] = false;
             }
         }
 
         // 给四周加上障碍物
-        for (let r = 0; r < this.rows; r ++ ) {
+        for (let r = 0; r < this.rows; r++) {
             g[r][0] = g[r][this.cols - 1] = true;
         }
 
-        for (let c = 0; c < this.cols; c ++ ) {
+        for (let c = 0; c < this.cols; c++) {
             g[0][c] = g[this.rows - 1][c] = true;
         }
 
         // 创建随机障碍物
-        for (let i = 0; i < this.inner_walls_count / 2; i ++ ) {
+        for (let i = 0; i < this.inner_walls_count / 2; i++) {
-            for (let j = 0; j < 1000; j ++ ) {
+            for (let j = 0; j < 1000; j++) {
                 let r = parseInt(Math.random() * this.rows);
                 let c = parseInt(Math.random() * this.cols);
-                if (g[r][c] || g[c][r]) continue;
+                // 两个对称的位置都没有障碍物
+                if (g[r][c] || g[this.rows - 1 - r][this.cols - 1 - c]) continue;
                 // 不能将障碍物生成到两条蛇的起始位置处(左下，右上)
                 if (r == this.rows - 2 && c == 1 || r == 1 && c == this.cols - 2)
                     continue;
                 // 每次将障碍物生成到对称的两个位置
-                g[r][c] = g[c][r] = true;
+                g[r][c] = g[this.rows - 1 - r][this.cols - 1 - c] = true;
                 break;
             }
         }
@@ -69,8 +78,8 @@ export class GameMap extends AcGameObject {
         if (!this.check_connectivity(copy_g, this.rows - 2, 1, 1, this.cols - 2))
             return false;
 
-        for (let r = 0; r < this.rows; r ++ ) {
+        for (let r = 0; r < this.rows; r++) {
-            for (let c = 0; c < this.cols; c ++ ) {
+            for (let c = 0; c < this.cols; c++) {
                 if (g[r][c]) {
                     // 每次添加一个障碍物
                     this.walls.push(new Wall(r, c, this));
@@ -81,11 +90,31 @@ export class GameMap extends AcGameObject {
         return true;
     }
 
+    add_listening_events() { // 绑定监听事件
+        this.ctx.canvas.focus(); // 聚焦
+        const [snake0, snake1] = this.snakes;
+
+        // 蓝方用wsad控制，红方用上下左右控制
+        this.ctx.canvas.addEventListener("keydown", e => {
+            if (e.key === 'w') snake0.set_direction(0);
+            else if (e.key === 'd') snake0.set_direction(1);
+            else if (e.key === 's') snake0.set_direction(2);
+            else if (e.key === 'a') snake0.set_direction(3);
+            else if (e.key === 'ArrowUp') snake1.set_direction(0);
+            else if (e.key === 'ArrowRight') snake1.set_direction(1);
+            else if (e.key === 'ArrowDown') snake1.set_direction(2);
+            else if (e.key === 'ArrowLeft') snake1.set_direction(3);
+        });
+    }
+
+
+
     start() {
         // 尝试1000次，直到找到符合条件的地图为止
-        for (let i = 0; i < 1000; i ++ ) 
+        for (let i = 0; i < 1000; i++)
             if (this.create_walls())
                 break;
+        this.add_listening_events();
     }
 
     update_size() { // 每过一帧重新生成新的地图尺寸
@@ -97,13 +126,53 @@ export class GameMap extends AcGameObject {
 
     update() { // 更新地图:每隔一帧都要重新渲染
         this.update_size(); // 更新地图大小
+        if (this.check_ready()) {
+            this.next_step(); // 进入下一回合
+        }
         this.render(); // 重新渲染
     }
 
+    check_ready() { // 判断两条蛇是否准备好进行下一步
+        for (const snake of this.snakes) {
+            if (snake.status !== "idle") return false;
+            if (snake.direction === -1) return false;
+        }
+        return true;
+    }
+
+    next_step() { // 让两条蛇进入下一回合
+        for (const snake of this.snakes) {
+            snake.next_step();
+        }
+    }
+
+    check_vaild(cell) { // 检测蛇的目标位置是否合法：是否撞到两条蛇的身体和障碍物
+        for (const wall of this.walls) {
+            if (wall.r === cell.r && wall.c === cell.c) { // 撞到墙了
+                return false;
+            }
+        }
+
+        for (const snake of this.snakes) {
+            let k = snake.cells.length;
+            // 特殊处理!!!
+            if (!snake.check_tail_increasing()) { // 当蛇为会前进的时候，蛇尾不需要判断，因为蛇头可以占据蛇尾的位置
+                k--;
+            }
+            for (let i = 0; i < k; i++) {  // 依次判断是否会撞到两条蛇的身体
+                if (snake.cells[i].r === cell.r && snake.cells[i].c === cell.c) { // 撞到蛇的身体了
+                    return false;
+                }
+            }
+        }
+
+        return true;
+    }
+
     render() {
         const color_even = "#AAD751", color_odd = "#A2D149";
-        for (let r = 0; r < this.rows; r ++ ) {
+        for (let r = 0; r < this.rows; r++) {
-            for (let c = 0; c < this.cols; c ++ ) {
+            for (let c = 0; c < this.cols; c++) {
                 if ((r + c) % 2 == 0) {
                     this.ctx.fillStyle = color_even;
                 } else {

web/src/assets/scripts/Snake.js

@@ -0,0 +1,173 @@
+import { AcGameObject } from "./AcGameObject";
+import { Cell } from "./Cell";
+
+export class Snake extends AcGameObject {
+    constructor(info,gamemap) { // 传入蛇的信息和地图
+        super();
+
+        this.id = info.id; // 哪条蛇
+        this.color = info.color; // 蛇的颜色
+        this.gamemap = gamemap; // 方便调用地图的有关参数
+        this.cells = [new Cell(info.r,info.c)] // cells存放蛇的坐标，cells[0]存放蛇头
+
+        this.speed = 5; // 定义蛇的速度，每秒走5个格子
+        this.direction = -1; // -1表示没有指令,0,1,2,3分别表示左右下左
+        this.status = "idle"; // idle表示静止,move表示移动,die表示死亡
+        this.next_cell = null; // 下一步的目标位置
+
+        // 0，1，2，3：上右下左
+        this.dr = [-1,0,1,0]; // 行方向的偏移量
+        this.dc = [0,1,0,-1]; // 列方向的偏移量
+
+        this.step = 0; // 蛇当前的回合数
+        this.eps = 1e-2; // 允许误差为0.01
+
+        this.eye_direction = 0;  // 左下角的蛇的眼睛朝上
+
+        if (this.id === 1) this.eye_direction = 2; // 右上角的蛇的眼睛朝下
+
+        // 定义蛇左右眼的x和y坐标的偏移量
+        this.eyes_dx = [
+            [-1,1],
+            [1,1],
+            [-1,1],
+            [-1,-1]
+        ];
+
+        this.eyes_dy = [
+            [-1,-1],
+            [-1,1],
+            [1,1],
+            [-1,1]
+        ];
+    
+    }
+ 
+    start() { // 第一帧调用该函数
+
+    }
+
+    update() { // 更新下一帧
+        if (this.status === "move") { // 只有下一步的状态为移动才可以移动
+            this.update_move(); // 蛇进行移动
+        }
+        this.render();
+    }
+ 
+    check_tail_increasing() {  // 前10步每步增加1，后面每三步增加1
+        if (this.step <= 10) return true;
+        if (this.step % 3 === 1) return true;
+        return false;
+    }
+
+    next_step() { // 将蛇的状态置为下一步
+        const d = this.direction;
+        // 更新下一步的位置
+        this.next_cell = new Cell(this.cells[0].r+this.dr[d],this.cells[0].c + this.dc[d]);
+        this.direction = -1; // 清空当前方向
+        this.status = "move"; // 改为移动
+        this.eye_direction = d; // 更新蛇的眼睛方向
+        this.step++; // 回合数加一
+
+        const k  = this.cells.length;
+        for (let i = k; i > 0; i--) {
+            // 每个数组元素先后移动一位，相当于复制了一份第一个元素
+            // 1,2,3 => 1,1,2,3
+            this.cells[i] = JSON.parse(JSON.stringify(this.cells[i-1])); 
+        }
+
+        if (!this.gamemap.check_vaild(this.next_cell)) { // 下一步不合法, 蛇直接去世
+            this.status = "die";
+        }
+        
+    }
+
+    set_direction(d) { // 通过读取用户输入来设置方向
+        this.direction = d;
+    }
+
+    update_move() { // 蛇进行移动
+        // // 蛇向右移动5个格子
+        // this.cells[0].x += this.speed * this.timedelta / 1000; // 注意每一帧不一定是1s
+
+        const dx = this.next_cell.x - this.cells[0].x;
+        const dy = this.next_cell.y - this.cells[0].y;
+
+        const distance = Math.sqrt(dx * dx+dy * dy); 
+        if (distance < this.eps) { // 移动到了目标点
+            this.cells[0] = this.next_cell; // 添加一个新蛇头
+            this.next_cell = null;
+            this.status = "idle"; // 走完了，停下来
+            if (!this.check_tail_increasing()) { // 蛇不变长,去掉蛇尾
+                this.cells.pop(); // 弹出蛇尾
+            }
+        }
+        else {
+            const move_distance = this.speed * this.timedelta / 1000; //移动距离
+            this.cells[0].x += move_distance * dx / distance;
+            this.cells[0].y += move_distance * dy / distance;
+
+            if (!this.check_tail_increasing()) { // 蛇不变长，蛇尾需要移动到目标位置
+                const k = this.cells.length;
+                const tail = this.cells[k-1],tail_target = this.cells[k-2];
+                const tail_dx = tail_target.x - tail.x;
+                const tail_dy = tail_target.y - tail.y;
+                tail.x +=  move_distance * tail_dx / distance;
+                tail.y +=  move_distance * tail_dy / distance;
+            }
+        }
+
+    }
+
+
+    render() { 
+        const L = this.gamemap.L; // 单位距离
+        const ctx = this.gamemap.ctx; // 画布
+
+        ctx.fillStyle = this.color; // 填充颜色
+
+        if (this.status === "die") {
+            ctx.fillStyle = "white";
+        }
+
+        for (const cell of this.cells) { // 将蛇用圆表示
+            ctx.beginPath();
+            // 前两个参数时圆心坐标，后面的
+            ctx.arc(cell.x * L,cell.y * L,L / 2 * 0.8, 0, Math.PI * 2);
+            ctx.fill();
+        }
+
+        for (let i = 1; i < this.cells.length; i++) {
+            const a = this.cells[i-1],b = this.cells[i];
+            if (Math.abs(a.x - b.x) < this.eps && Math.abs(a.y-b.y) < this.eps) {
+                continue;
+            }
+
+            if (Math.abs(a.x - b.x) < this.eps) {
+                // 矩形起始点的 x轴坐标、y轴坐标、矩形width、矩形height
+                // 用Math.min()是因为这两个矩阵上下关系不知道
+                ctx.fillRect((a.x - 0.4) * L,Math.min(a.y,b.y) * L,L*0.8,Math.abs(a.y-b.y) * L);
+            }
+            else {
+                ctx.fillRect(Math.min(a.x,b.x) * L,(a.y - 0.4) * L,Math.abs(a.x-b.x) * L,L*0.8);
+            }
+        }
+
+
+        // 画出蛇的眼睛
+
+        ctx.fillStyle = "black";
+
+        for (let i = 0; i < 2 ; i++) {
+            const eye_x = (this.cells[0].x + this.eyes_dx[this.eye_direction][i] * 0.2) * L;
+            const eye_y = (this.cells[0].y + this.eyes_dy[this.eye_direction][i] * 0.2) * L;
+
+            // 画眼睛
+
+            ctx.beginPath();
+            ctx.arc(eye_x,eye_y,L*0.05,0,Math.PI*2);
+            ctx.fill();
+        }
+
+    }
+}

web/src/components/GameMap.vue

@@ -1,6 +1,7 @@
 <template>
     <div ref="parent" class="gamemap"> <!--使用下面返回的parent-->
-        <canvas ref="canvas"></canvas> <!--使用下面返回的canvas-->
+        <!--tabindex=0获取用户的输入操作-->
+        <canvas ref="canvas" tabindex="0"></canvas> <!--使用下面返回的canvas-->
     </div>
 </template>