Code archives/Graphics/5 simple overlay effects

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5 simple overlay effects by WarpZone
(Posted 22 years ago)
These functions combine two textures, the same way you can combine layers in some paint programs. These functions are not fast enough to use in a real-time game, but they are useful for processing 2D images before the game starts, or for image processing tools or other editors.

Note: Each image you use must be the same size as specified in the line 
Global Target= CreateImage(64,64)


It should be easy enough to produce other kinds of effects. What can you come up with? Feel free to add your own variants here! :) 
Graphics3D 800,600,16,0
camera=CreateCamera()

Global Target= CreateImage(64,64)
Global Source1= LoadImage("tex3.bmp")
Global Source2= LoadImage("tex4.bmp")

LightenBlend(Source1,Source2,Target)

Repeat
Mil1=MilliSecs() 
UpdateWorld
RenderWorld
SetBuffer BackBuffer()
CopyRect 0,0,64,64,0,0,ImageBuffer(Target),BackBuffer() 
Mil2= MilliSecs() 
Color 255,255,0
Text 4,500,"Render time: "+(Mil2-Mil1)
Flip
Until KeyDown(1)

Function AddBlend(SourceTexture1,SourceTexture2,TargetTexture)
  For x = 0 To 64
    For y = 0 To 64
      SetBuffer ImageBuffer(SourceTexture1)
      GetColor x,y
      r1#=ColorRed()
      g1#=ColorGreen()
      b1#=ColorBlue()
      SetBuffer ImageBuffer(SourceTexture2)
      GetColor x,y
      r2#=ColorRed()
      g2#=ColorGreen()
      b2#=ColorBlue()
      SetBuffer ImageBuffer(TargetTexture)
      sumr=r1+r2
      sumg=g1+g2
      sumb=b1+b2
      If sumr>255 Then sumr=255
      If sumg>255 Then sumg=255
      If sumb>255 Then sumb=255
      Color sumr,sumg,sumb
      Plot x,y
    Next
  Next
End Function

Function MultiplyBlend(SourceTexture1,SourceTexture2,TargetTexture)
  For x = 0 To 64
    For y = 0 To 64
      SetBuffer ImageBuffer(SourceTexture1)
      GetColor x,y
      r1#=ColorRed()
      g1#=ColorGreen()
      b1#=ColorBlue()
      SetBuffer ImageBuffer(SourceTexture2)
      GetColor x,y
      r2#=ColorRed()
      g2#=ColorGreen()
      b2#=ColorBlue()
      SetBuffer ImageBuffer(TargetTexture)
      sumr=r1*r2/256
      sumg=g1*g2/256
      sumb=b1*b2/256
      Color sumr,sumg,sumb
      Plot x,y
    Next
  Next
End Function

Function DifferenceBlend(SourceTexture1,SourceTexture2,TargetTexture)
  For x = 0 To 64
    For y = 0 To 64
      SetBuffer ImageBuffer(SourceTexture1)
      GetColor x,y
      r1#=ColorRed()
      g1#=ColorGreen()
      b1#=ColorBlue()
      SetBuffer ImageBuffer(SourceTexture2)
      GetColor x,y
      r2#=ColorRed()
      g2#=ColorGreen()
      b2#=ColorBlue()
      SetBuffer ImageBuffer(TargetTexture)
      If r1>r2 Then sumr=r1-r2 Else sumr=r2-r1
      If g1>g2 Then sumg=g1-g2 Else sumg=g2-g1
      If b1>b2 Then sumb=b1-b2 Else sumb=b2-b1
      Color sumr,sumg,sumb
      Plot x,y
    Next
  Next
End Function

Function LightenBlend(SourceTexture1,SourceTexture2,TargetTexture)
  For x = 0 To 64
    For y = 0 To 64
      SetBuffer ImageBuffer(SourceTexture1)
      GetColor x,y
      r1#=ColorRed()
      g1#=ColorGreen()
      b1#=ColorBlue()
      SetBuffer ImageBuffer(SourceTexture2)
      GetColor x,y
      r2#=ColorRed()
      g2#=ColorGreen()
      b2#=ColorBlue()
      SetBuffer ImageBuffer(TargetTexture)
      If r1>r2 Then sumr=r1 Else sumr=r2
      If g1>g2 Then sumg=g1 Else sumg=g2
      If b1>b2 Then sumb=b1 Else sumb=b2
      Color sumr,sumg,sumb
      Plot x,y
    Next
  Next
End Function

Function DarkenBlend(SourceTexture1,SourceTexture2,TargetTexture)
  For x = 0 To 64
    For y = 0 To 64
      SetBuffer ImageBuffer(SourceTexture1)
      GetColor x,y
      r1#=ColorRed()
      g1#=ColorGreen()
      b1#=ColorBlue()
      SetBuffer ImageBuffer(SourceTexture2)
      GetColor x,y
      r2#=ColorRed()
      g2#=ColorGreen()
      b2#=ColorBlue()
      SetBuffer ImageBuffer(TargetTexture)
      If r1<r2 Then sumr=r1 Else sumr=r2
      If g1<g2 Then sumg=g1 Else sumg=g2
      If b1<b2 Then sumb=b1 Else sumb=b2
      Color sumr,sumg,sumb
      Plot x,y
    Next
  Next
End Function