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次のSchemeコードは宇宙船を使ったゲームに関するもので、今のところ宇宙船の燃料がなくなったときを考慮していません。これは私がやろうとしていることです. コードは次のとおりです
。これは問題 rrset のコードです -- 月着陸船 

(define (update ship-state fuel-burn-rate)  
 (make-ship-state  
   (+ (height ship-state) (* (velocity ship-state) dt)) ; height  
   (+ (velocity ship-state)  
      (* (- (* engine-strength fuel-burn-rate) gravity)  
         dt))                                           ; velocity  
   (cond (<= (fuel 0)  
        ((write-line "no fuel left")   
          'game-over)  
         (else  
           (- (fuel ship-state) (* fuel-burn-rate dt))))))       ; fuel  

(define (lander-loop ship-state)  
  (show-ship-state ship-state)  
  (if (landed? ship-state)  
  (end-game ship-state)  
  (lander-loop (update ship-state (get-burn-rate)))))  

(define (show-ship-state ship-state)  
  (write-line   
    (list 'height (height ship-state)  
          'velocity (velocity ship-state)  
          'fuel (fuel ship-state))))  

(define (landed? ship-state)  
  (<= (height ship-state) 0))  

(define (end-game ship-state)  
  (let ((final-velocity (velocity ship-state)))  
       (write-line final-velocity)  
       (cond ((>= final-velocity safe-velocity)  
               (write-line "good landing")  
               'game-over)  
             (else  
               (write-line "you crashed!")  
               'game-over))))  

(define (get-burn-rate)  
  (if (= (player-input) burn-key)  
      1  
      0))  

(define (play) (lander-loop (initial-ship-state)))  

(define (initial-ship-state)  
  (make-ship-state 50       ; 50 km high  
                   0        ; not moving (0 km/sec)  
                   20))     ; 20 kg of fuel left  

(define dt 1)               ; 1 second interval of simulation  

(define gravity 0.5)        ; 0.5 km/sec/sec  

(define safe-velocity -0.5) ; 0.5 km/sec or faster is a crash  

(define engine-strength 1)  ; 1 kilonewton-second  

(define (player-input)  
  (char->integer (prompt-for-command-char " action: ")))  

(define burn-key 32)   ;space key  

(define (make-ship-state height velocity fuel)  
  (list 'HEIGHT   height  
        'VELOCITY velocity  
        'FUEL     fuel))  

(define (height state) (second state))  
(define (velocity state) (fourth state))  
(define (fuel state) (sixth state))  

(define (second l) (cadr l))  
(define (fourth l) (cadr (cddr l)))  
(define (sixth l) (cadr (cddr (cddr l))))  

; Users of DrScheme or DrRacket: add these for compatibility with MIT Scheme...  
(define (write-line x)  
  (display x)  
  (newline))  

(define (prompt-for-command-char prompt)  
  (display prompt)  
  (read-char))

それを変更するために、「更新」手順を変更したため、条件ステートメントがあります。 

(define (update ship-state fuel-burn-rate)  
  (make-ship-state  
   (+ (height ship-state) (* (velocity ship-state) dt)) ; height  
   (+ (velocity ship-state)  
      (* (- (* engine-strength fuel-burn-rate) gravity)  
         dt))                                           ; velocity  
   (cond (<= (fuel 0)  
        ((write-line "no fuel left")   
          'game-over)  
         (else  
           (- (fuel ship-state) (* fuel-burn-rate dt))))))

ただし、これは機能しません。

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1 に答える 1

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lander-loopプロシージャに条件を追加したいと思うでしょう。これは、各サイクルでゲームが終了したかどうかをチェックするコードの一部です。

(define (lander-loop ship-state)  
  (show-ship-state ship-state)
  (if (or (landed? ship-state) (<= (fuel ship-state) 0))
    (end-game ship-state)
    (lander-loop (update ship-state (get-burn-rate)))))

end-game次に、燃料切れメッセージを手順に追加できます。

于 2013-02-03T03:27:36.977 に答える