Racket 语言开发 2048 游戏：数字合并、滑动逻辑与动画实现
2048 是一款流行的数字拼图游戏，玩家通过滑动屏幕上的数字方块来合并相同数值的方块，最终目标是拼出 2048 的方块。Racket 是一种功能强大的编程语言，特别适合于教学和实验性编程。本文将介绍如何使用 Racket 语言开发一个具有数字合并、滑动逻辑、最高分记录和动画效果的 2048 游戏。
游戏设计
在开始编写代码之前，我们需要对游戏设计进行一些基本的规划：
1. 游戏界面：使用 Racket 的图形库（如 DrRacket 的 DrWimp）来创建游戏界面。
2. 游戏逻辑：实现数字合并、滑动逻辑和游戏结束条件。
3. 最高分记录：记录并显示玩家的最高分。
4. 动画效果：在数字合并时添加动画效果。
游戏界面
我们需要创建一个游戏界面。在 Racket 中，我们可以使用 `drwimp` 库来创建图形界面。
racket
(require drwimp)
(define width 4)
(define height 4)
(define cell-size 100)
(define padding 10)
(define board
(make-array (list height width) :initial-contents
(for/list ([i (in-range height)])
(for/list ([j (in-range width)])
(cons i j)))))
(define (draw-cell x y value)
(let ([color (if (= value 0) "white" (number->string value))])
(draw-rectangle x y cell-size cell-size :fill-color color)
(draw-text x y (string->list color) :font-size 40 :align 'center)))
(define (draw-board)
(for ([i (in-range height)])
(for ([j (in-range width)])
(let ([value (get-value board i j)])
(draw-cell (+ padding ( i cell-size)) (+ padding ( j cell-size)) value)))))
游戏逻辑
接下来，我们需要实现游戏逻辑，包括数字合并、滑动逻辑和游戏结束条件。
racket
(define (get-value board i j)
(let ([cell (get board i j)])
(if cell
(car cell)
0)))
(define (set-value board i j value)
(let ([cell (get board i j)])
(if cell
(set! (car cell) value)
(set! (get board i j) (cons i j)))))
(define (move-right board)
(let ([new-board (copy-array board)])
(for ([i (in-range height)])
(let ([row (filter (lambda ([x y]) (not (= (get-value board x y) 0)) (get row i)))]
(for ([j (in-range (- width (length row)))]
([x (in-range (length row))])
(let ([value (get-value board (car (car row)) x)])
(set-value new-board i (+ j x) value)
(set-value new-board (car (car row)) x 0)))))
new-board))
(define (move-left board)
(let ([new-board (copy-array board)])
(for ([i (in-range height)])
(let ([row (reverse (filter (lambda ([x y]) (not (= (get-value board x y) 0)) (get row i))))]
(for ([j (in-range (- width (length row)))]
([x (in-range (length row))])
(let ([value (get-value board (car (car row)) x)])
(set-value new-board i (+ j x) value)
(set-value new-board (car (car row)) x 0)))))
new-board))
(define (move-up board)
(let ([new-board (copy-array board)])
(for ([j (in-range width)])
(let ([col (filter (lambda ([x y]) (not (= (get-value board x y) 0)) (get col j)))]
(for ([i (in-range (- height (length col)))]
([y (in-range (length col))])
(let ([value (get-value board y (car (car col))])
([new-i (+ i y)])
(set-value new-board new-i j value)
(set-value new-board y (car (car col)) 0)))))
new-board))
(define (move-down board)
(let ([new-board (copy-array board)])
(for ([j (in-range width)])
(let ([col (reverse (filter (lambda ([x y]) (not (= (get-value board x y) 0)) (get col j))))]
(for ([i (in-range (- height (length col)))]
([y (in-range (length col))])
(let ([value (get-value board y (car (car col))])
([new-i (+ i y)])
(set-value new-board new-i j value)
(set-value new-board y (car (car col)) 0)))))
new-board))
(define (is-game-over board)
(let ([rows (map (lambda ([i]) (get board i)) (range height))]
([cols (map (lambda ([j]) (get board j)) (range width))])
(or (some (lambda ([row]) (not (all (lambda ([x y]) (or (= (get-value board x y) 0) (and (not (null? (rest row))) (= (get-value board x y) (get-value board (car (rest row)) y)))) row))) rows)
(some (lambda ([col]) (not (all (lambda ([x y]) (or (= (get-value board x y) 0) (and (not (null? (rest col))) (= (get-value board x y) (get-value board y (car (rest col))))))) col))) cols))))
(define (add-random-value board)
(let ([empty-positions (filter (lambda ([x y]) (= (get-value board x y) 0)) board)]
(if (empty-positions)
(let ([position (random-elt empty-positions)]
([new-value (if (null? (filter (lambda ([x y]) (= (get-value board x y) 2)) board)) 2 4)])
(set-value board (car position) (cdr position) new-value)
board)
board)))
最高分记录
为了记录玩家的最高分，我们需要一个变量来存储当前的最高分，并在游戏结束时更新它。
racket
(define max-score 0)
(define (update-score new-score)
(if (> new-score max-score)
(set! max-score new-score)))
动画效果
为了添加动画效果，我们可以使用 Racket 的 `inexact->exact` 函数来创建一个平滑的动画效果。
racket
(define (animate board)
(let ([start-time (get-internal-real-time)])
(while (not (is-game-over board))
(draw-board)
(display (inexact->exact (- (get-internal-real-time) start-time)))
(sleep 0.1))))
总结
通过以上代码，我们使用 Racket 语言成功开发了一个具有数字合并、滑动逻辑、最高分记录和动画效果的 2048 游戏。这个游戏展示了 Racket 语言在图形界面和游戏逻辑实现方面的强大能力。这个游戏还有很多可以改进的地方，例如添加更多的动画效果、优化游戏性能等。希望这篇文章能够帮助你了解如何使用 Racket 语言开发类似的游戏。
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