Using Timer With Sinus To Flash A Message

[kevin]

 Using Timer With Sinus  To Flash A Message

 This example flashes a text message at a constant rate regardless of the computers speed.  

PlayBASIC Code: [Select]

   StartTime=Timer()
Do
   Cls 0
   CurrentTime=Timer()

   TimePast=CurrentTime-StartTime
   Scaler#=TimePast/1000.0
   
   Angle#=wrapangle((360*4)*Scaler#,0)

   If Sin(Angle#)>0
      centertext 400,300,"Some Message"

   endif


   Sync
loop

Using Timer With Sinus  To Fade In/Out At Fixed Speed

This is how I normally used sinus to fade in/out.  

PlayBASIC Code: [Select]

   loadfont "veranda",1,128,0

   Cls 255
   boxc 0,0,32,32,true,$ff00ff
   boxc 32,32,64,64,true,$ff00ff
   getimage 1,0,0,64,64

   TileIMage 1,0,0,false
   GetImage 1,0,0,256,256

   StartTime=Timer()

   

Do
   CurrentTime=Timer()

   TimePast=CurrentTime-StartTime

   Scaler#=TimePast/1000.0

   Xpos=((64*4))*Scaler#
   Ypos=((64*2))*Scaler#

   tileimage 1,Xpos,Ypos,false
   
   Angle#=wrapangle((360/2)*Scaler#,0)

   ink rgbfade($404040,50+SinRadius(Angle#,50))
   
   centertext 395,195,"Some Message"
   ink rgbfade($ffffff,50+SinRadius(Angle#,50))
   centertext 400,200,"Some Message"

   Sync
loop


 

[monkeybot]

Hi Kevin,

please could you explain why this is better than just having an incremental counter..
Thanks

[kevin]

 Basing it (or anything) on time, means It doesn't matter how fast or slow the computer runs, as the duration and frequency are the same.   

[monkeybot]

ahhh yes duration...nice one,elegant.

[kevin]

  Using Timer For Constant Movement

  This example is in the same theme as the others, but this time we're plotting motion.  When objects are created they'd each given a start and ending coordinate,  plus a duration in milliseconds of how long this journey will take.   Rather than giving each object a speed per frame, the code works off how much time has past since the object was spawned, then converts this into a scaler.   We can use the scaler to calc the position of the object over it's life span.    So they'll each reach their destination at the same time regardless of how fast the computer is running the program.  

PlayBASIC Code: [Select]

;   setfps 50
   
   
   Type tObject
   
         StartTime ;  When the object was born
         Duration  ;  The Life span in milliseconds on the object
         EndTime    ;  When we expect this object to be dead
   
         StartingX   ; Starting X & Y cordinate
         StartingY
         
         EndingX
         EndingY

         Size         ; The size of the object

         Colour      ; The COlour of this object
   
   EndType

   ; create the list for the ball objects 
   Dim Ball as tObject List
   

   ; ------------------------------------------------------------
   ;                    >> Programs Main Loop <<
   ; ------------------------------------------------------------
   Do

      cls 
      
   
      CurrentTime=Timer()
         
      if NExtAdd<CurrentTime
         if Rnd(100)>90
            ; the length of time it taks the object to move between the two points
            for lp=0 to rnd(5)
               Duration= 1000*rnd(10)
               X1=rnd(800)
               y1=rnd(600)
               X2=rnd(800)
               y2=rnd(600)
               AddBall(X1,y1,x2,y2,Duration,CurrentTime)
            next
         endif

         ; dont allow new objects to be added for at least 20 milliseconds (50th
         ; of a second
         NExtAdd=CurrentTime+20
      endif

      lockbuffer
      for each Ball()
      
            if CurrentTime<Ball.EndTime
                  if CurrentTime>=Ball.StartTime
                     ; Calc how much time has past 
                        TimePast#=CurrentTime-Ball.StartTime
                     
                     ; Convert the the time past, into a scaler the represent
                     ; how far along this object has moved since it was born.
                        Scaler#=TimePast#/Ball.Duration
      
                     ; get the difference between the start and end positions
                     ; and scale them by the time past scaler                  
                        CurrentX=(Ball.EndingX-Ball.StartingX)*Scaler#      
                        CurrentY=(Ball.EndingY-Ball.StartingY)*Scaler#      
            
                     ; add on the objects starting position      
                        CurrentX+=Ball.StartingX
                        CurrentY+=Ball.StartingY

                        Size#=Ball.Size*(1-Scaler#)

                     ; draw it
                        Circlec CurrentX,CurrentY,Size#,true,Ball.COlour      
                  endif

            else
                  ; This Ball is now dead
                  Ball= Null
            
            endif
      
      next
      unlockbuffer

      
      

      ; display the FPS 
      Print Fps()

      Sync

   loop



Function AddBall(X1,y1,x2,y2,Duration,CurrentTime)

      Ball = New Tobject
      Ball.StartTime =CurrentTime
      Ball.Duration   =Duration
      Ball.EndTime    =CurrentTime+Duration
      
      Ball.StartingX=x1
      Ball.StartingY=Y1

      Ball.EndingX=x2
      Ball.EndingY=Y2
      Ball.Colour=rndrgb()

      Ball.Size = rndrange(10,30)

EndFunction

 Pig Tails

 Hold space to see pig tails.   Here we're plotting a circular movement while it moves between points.  

PlayBASIC Code: [Select]

;   setfps 20
   
   
   Type tObject
   
         StartTime ;  When the object was born
         Duration  ;  The Life span in milliseconds on the object
         EndTime    ;  When we expect this object to be dead
   
         StartingX   ; Starting X & Y cordinate
         StartingY
         
         EndingX
         EndingY


         Angle#      ; From start to finish

         Size         ; The size of the object

         Colour      ; The COlour of this object
   
   EndType

   ; create the list for the ball objects 
   Dim Ball as tObject List
   

   ; ------------------------------------------------------------
   ;                    >> Programs Main Loop <<
   ; ------------------------------------------------------------
   Do

      if Spacekey()=false
         cls 
      endif   
   
      CurrentTime=Timer()
         
      if NExtAdd<CurrentTime
         if Rnd(100)>90
            ; the length of time it taks the object to move between the two points
               Duration= 1000*rnd(10)
               X1=rnd(800)
               y1=rnd(600)
               X2=rnd(800)
               y2=rnd(600)
               AddBall(X1,y1,x2,y2,Duration,CurrentTime)
         endif

         ; dont allow new objects to be added for at least 20 milliseconds (50th
         ; of a second
         NExtAdd=CurrentTime+20
      endif

      lockbuffer
      for each Ball()
      
            if CurrentTime<Ball.EndTime
                  if CurrentTime>=Ball.StartTime
                     ; Calc how much time has past 
                        TimePast#=CurrentTime-Ball.StartTime
                     
                     ; Convert the the time past, into a scaler the represent
                     ; how far along this object has moved since it was born.
                        Scaler#=TimePast#/Ball.Duration
      
                     ; get the difference between the start and end positions
                     ; and scale them by the time past scaler                  
                        CurrentX=(Ball.EndingX-Ball.StartingX)*Scaler#      
                        CurrentY=(Ball.EndingY-Ball.StartingY)*Scaler#      
            

                     ;  Get Angle 90 degrees from the direction we've moving in
                        Angle#=wrapangle(Ball.Angle#+90)

                     ; Over the duraiton of the objects life, we want to to
                     ; turn through 360 degrees 5 times
                        Angle#+=(360*5)*Scaler#
                        
                     ; Calc it's size at this time 
                        Size#=Ball.Size*(1-Scaler#)

                     ; add on the objects starting position      
                        CurrentX+=Ball.StartingX+CosRadius(Angle#,size#*5)
                        CurrentY+=Ball.StartingY+SinRadius(Angle#,size#*5)
                     
                     ; draw it
                        Circlec CurrentX,CurrentY,Size#,true,Ball.COlour      

                  endif

            else
                  ; This Ball is now dead
                  Ball= Null
            
            endif
      
      next
      unlockbuffer

      
      

      ; display the FPS 
      Text 0,0,Fps()
      text 0,30,"Hold space"
      Sync

   loop



Function AddBall(X1,y1,x2,y2,Duration,CurrentTime)

      Ball = New Tobject
      Ball.StartTime =CurrentTime
      Ball.Duration   =Duration
      Ball.EndTime    =CurrentTime+Duration
      
      Ball.StartingX=x1
      Ball.StartingY=Y1

      Ball.EndingX=x2
      Ball.EndingY=Y2

      Ball.Angle#=getangle2d(x1,y1,x2,y2)

      Ball.Colour=rndrgb()

      Ball.Size = rndrange(10,30)

EndFunction