Applying a Classic Sine wave effect to an image

[kevin]

PlayBASIC Code: [Select]

;---------------------------------------------------------------------; Sine Wave Image..;---------------------------------------------------------------------

   OpenScreen 640,480,16,2   

   W=GetScreenWidth()
   H=GetScreenHeight()

   Global TempStripImage=2
   CreateImage 1,w,h
   CreateImage TempStripImage,w,1
  
   CreateConvexShape 1,100,5    

   Do
  RenderToImage 1     ;     Cls 0

     bw=32
     bh=32
     Ypos=ScrollY
     Ypos2=Ypos+bh
     For ylp=0 To h Step bh
    Xpos=ScrollX
    Xpos2=Xpos+bw
    Toggle=Ylp And 1
    For xlp=0 To w Step bw
       If Toggle
      BoxC Xpos,Ypos,Xpos2,Ypos2,RGB(255,0,0)
       Else
      BoxC Xpos,Ypos,Xpos2,Ypos2,RGB(155,0,255)
       EndIf
       toggle=1-toggle       
       Xpos=Xpos2
       Xpos2=Xpos2+bw    
    Next         
    Ypos=Ypos2
    Ypos2=Ypos2+bh    
     next


     Angle#=WrapAngle(angle#,1)
     RotateShape 1,angle#,1
     Ink RGBFade($223344,70+Cos(angle)*30)
     DrawShape 1,w/2,h/2,3

     Ink RGBFade($223344,70+Sin(angle)*30)
     DrawShape 1,w/2,h/2,1


     Ink $ffffff
     CenterText w/2,h/2-50,"Sine Wave Screen "+Str$(w)+"*"+Str$(h)
  
     SineCopyImageToScreen(1,15)
    
  Sync
   Loop




Function SineCopyImageToScreen(SrcImage,wavesize#)
   Static WaveAngle#
   w=GetImageWidth(SrcImage)
   Angle#=WaveAngle#
  For Ylp=0 To GetImageHeight(srcImage)
     RenderToImage SrcImage   
     GetImage TempStripImage,0,ylp,w,ylp+1   
     RenderToScreen
     DrawImage TempStripIMage,SinRadius(Angle#,WaveSize#),ylp,0     
     INC Angle#     
  Next
   WaveAngle#=WrapAngle(WaveAngle#,2)
EndFunction

[Draco9898]

VERY COOL  :blink:

I just shoved it into my game and made it move with the mouse!
:rolleyes:
Looks even cooler when you move it around and distort stuff

[Draco9898]

Looks even stranger if you make the
For Ylp=0 To GetImageHeight(srcImage)

go in Steps of 2......... :ph34r:
But I suppose thats because every other pixel is getting missed

I think I get how this works.....you capturing the screen as an image THEN your using  Static WaveAngle# and I'm not sure what the static commands does, but then you rip the image into Xwidth by 1 pixel height strips, then you paste enough of these on top of each other to get the original image back, but you've moved all the 'strips' with SinRange? and this causes the caustic effect?

ALSO: Changing the code by taking out the Static takes away all the movement and just leaves you with a  trick mirror like image and changing INC angle to DEC angle causes the effect to 'run' in the other direction...

I don't think I can think of a faster way to do this effect... :huh:


I have now also altered the code to so whatever is under or near the image 'waves' get affected as well

The only idea I have for making it faster is direct pixel access? Not sure.


Also one question: ARRAYS arn't globial by defult?  :unsure:

[kevin]

The Static commands allows a variable within a function to keep it's value between calls.  Normally these variables are local and thus the values/data are destroyed each time the function call has ended.

Dim's are global by default...

However, if you Dim an Array inside a function, then it's LOCAL (only visible) to the function within which it appears..