Handling Multiple Animations using Timer()

[kevin]

 Handling Multiple Animations using Timer()

 
  This example demo's how to handle collections of game objects all animating independently of each other.

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;*=------------------------------------------------------------------------=*   
;
;                    >> Handling Multiple Animations Using Timer<<
;
;                         Code By: Kevin Picone
;
;           Copyright 2009 by Kevin Picone, All Rights Reserved.
;
;*=-------------------------------------------------------------------------=*   
;
; About:
; ======
;
;    This example demonstrates one approach for animating multiple game objects
; base upon the system timer().   The demo displays a grid of doors, each one
; is represented on screen as a line.  So visually it's not too interesting. 

;    When the user clicks a door, the door will swing open then automatically
; close.  It could stay open if you like, but I didn't bother.  The interesting
; part is the each door has local animation based upon the time it's been open.  
;
;    What's local animation ?   There's two main types of animation approaches
; used in games programming,  Local and Global.  Local systems are where the
; game object includes animation counters/timers internally, so it's keeping
; track of it's animation state itself.    In global Animation, the game object
; gets it's current frame (animation state) from an external source, thus
; allowing many objects to be animated in unison.       Given the game objects
; in the demo,  each need to animate separately of each other, we'll need to
; take an local animation approach.
;
;   So how we do it ? Well, the mechanics are really pretty simple.   In this
; example, we're initializing the doors to give them a screen position and a
; state.  Each door starts in it's closed state.
;
;   During the programs main loop, we're running through the array of doors.  
; For each door,  we check it's state.  
;
;       If the Door is currently closed, then we check to see if the user
;                    is clicking the mouse upon this door.   If they are,
;                    we change this doors state to Opening and set this
;                    doors Starting animation time. If they didn't, we just
;                    continue on to draw the door.
;
;      If a door is opening or closing,  we apply it's animation logic code.
;                   In this example, we calc the elapsed time (the time from
;                   when the door started to open) in milliseconds .   Then
;                   we use  this time to calculate the doors swing angle and
;                   it's current state.      In the code, one full cycle of
;                   swing animation will take 1000 milliseconds (1 second),
;                    1/2 a second to open and the 1/2 a second to close.     
;
;   So,
;
;        * if the elapsed time is less than 500 milliseconds, the door
;            is opening.  
;
;        * if the elapsed time is greater than 500 milliseconds, the door
;          is closing.  
;
;    And finally if the elapsed time is greater than 1000 milliseconds, the
;  door has closed and it's state is reset to closed.
;
;    So since each door holds it's state and animation timers internally, the
;  same basic logic can be applied to any number of  game objects.
;
;
; Controls:
; ========
;
;     Mouse = Click the mouse on lines
;           ESC = EXIT
;
;
;*=-----------------------------------------------------------------------------=*   





   // Define the some constants that we'll use for the various door states
      Constant DoorState_Closed       =1
      Constant DoorState_Opening    =2
      Constant DoorState_Closing       =3


   // Define the Type to hold everything about the door
      Type tDoor
         state
         X,Y
         Colour
         Size
         AnimationStartTime   
      EndType

   // Create an array to hold a bunch of doors in it
      MaxDoors=50   
      Dim Doors(MaxDoors)  as tdoor
      

   // Run through and init all of the Doors positions on screen and
   // their size and colours
      Xpos=50
      Ypos=100

      For lp=1 to MaxDoors

         // Set the Doors state   
            Doors(lp).State      =DoorState_Closed

         // set this doors doors position on screen
            Doors(lp).x          =Xpos
            Doors(lp).y          =Ypos
   
         // set its' colour and size
            Doors(lp).Colour      =rndrgb()
            Doors(lp).Size         =50

         // move the position coords to where the next door
         // will be      
            Xpos=Xpos+100
            if Xpos=>700
               Xpos=50
               Ypos=Ypos+100
            endif
      next

      

;*=------------------------------------------------------------------------=*   
;                              >> Main LOOP <<
;*=------------------------------------------------------------------------=*   

 // Start of programs main DO/LOOP   
   Do

      // Clear Screen to black
         Cls rgb(0,0,0)

   
      // Get Mouse state at start of frame.
         mx=mousex()
         my=mousey()
         mb=mousebutton()

      // Get the current Time (in milliseconds)
         CurrentTime=Timer()

      // Run through and arocess all doors in the Doors() array
         For lp=1 to MaxDoors

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