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`(kakko ,man)

Find a guide into tomorrow by taking lessons from the past

Lisp Game Programming <Step8-1>

shipのstateが爆発中の状態ではなく、且つshotがdeadの状態の時、zキーを押すとshotの発射位置を計算してshotのstateをaliveにし、shot音を出して16dotづつ移動するプログラム

;; step8 <Shot>
;; -----------------------------------------------------------------------------------------------
(defgeneric Move-shot (shot))

(defmethod Move-shot (shot)
  (when (= (state shot) 1) ; shot is alive
    (decf (y shot) (dy shot))) ; shot 16 dot up
  (when (< (y shot) -32) ; out of screen
    (setf (state shot) 0))) ; shot off

(defgeneric Set-shot (shot ship keystate))

(defmethod Set-shot (shot ship keystate)
  (when (and (/= (state ship) 2) ; if ship is not explode
                      (= (state shot) 0) ; and shot is dead
         (eql (z keystate) t)) ; and set z key
    (setf (y shot) (- (y ship) (height shot))) ; set shot position
    (setf (x shot) (x ship))
    (setf (state shot) 1) ; shot on
    (Play-sample *shot-sound*) ; shot sound
    (setf (z keystate) nil))) ; reset z key

メインルーチンは以下

(defun Common-shooter ()
  "main routine"
  (sdl:with-init (sdl:sdl-init-video sdl:sdl-init-audio) ; use video and audio
  (sdl:window 640 480 :position #(192 50) ; size 640*480, position x(192) y(50)
                                       :title-caption "THE SHOOTER"
                                       :icon-caption "THE SHOOTER"
                                       :double-buffer T)
                                     ; :fullscreen T)
   ; step 3
  (Initialize) ; graphics initialize
   ; step 5
  (Set-font) ; set font 
  ; step 2 
  (Open-sound) ; open audio and load sound data 
  ; step 2
  (Play-music *bg-music*) ; play music
  ; step 3 - 8
  (let ((keystate (make-instance 'keystate)) ; step 6 add sentence
         (game-field (make-instance 'game-field)) ; step 7 add sentence
         (ship (make-instance 'entity :imageid 0 :id 0 :x 224 :y 416
                                                     :width 32 :height 32 :dx 4 :dy 4 :state 1))(
         (score-ship (make-instance 'object :imageid 0 :id 0 :x 496 :y 128))
    (shot (make-instance 'entity :imageid 0 :height 32 :dy 16 :id 1 :state 0)) ; step 8 add sentence
         (mapchip (make-instance 'object :imageid 1 :id 0)))

  (sdl:update-display)
  (sdl:with-events (:poll)
  (:quit-event ()
    ; step 2
    (Stop-sound) ; sample and music stop
    (Close-sound) ; close audio
      t)
    ; step 6
    (:key-down-event (:key key)
      (if (sdl:key= key :SDL-KEY-ESCAPE)
         (sdl:push-quit-event)
         (Update-keystate key t keystate)))
    (:key-up-event (:key key)
      (Update-keystate key nil keystate))
    (:idle ()
    ; Game body

      ; step 6
   (Move-ship ship keystate)
   ; step 7
   (Fix-ship-position ship game-field)
      ; step 8
      (Move-shot shot)
      (Set-shot shot ship keystate)
 
    ; step 4
      (Scroll mapchip) ; scroll background
      ; step 3
      (when (= (state ship) 1)
        (Draw ship)) ; draw ship
      ; step 8
      (when (= (state shot) 1)
        (Draw shot)) ; draw shot
      ; step 5
      (Score-panel score-ship) ; draw score panel

  (sdl:update-display))))))

こんな感じでzキーを押すと音を出してshotが上に移動していく

f:id:tomekame0126:20140707222026p:plain