Cheap lighting effect

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SoCoder -> Snippet Home -> Graphical Effects

Jayenkai	Created : 18 June 2007 System : Windows Language : Blitz Cheap lighting effect But probably slow!
Using two seperate versions of the same set of graphics, one lit, and one unlit, you can then draw areas of Masked Color to allow the lit areas to shine through (or reversed, show the unlit areas for shadows.) Graphics 800,600,32,2 GreyBuffer=CreateImage(800,600):MaskImage GreyBuffer,255,0,255 ColorBuffer=CreateImage(800,600):MaskImage ColorBuffer,255,0,255 OverlayBuffer=CreateImage(800,600):MaskImage OverlayBuffer,255,0,255 ;When you go to draw your screen.. LockBuffer ImageBuffer(ColorBuffer) LockBuffer ImageBuffer(GreyBuffer) For x=0 To 799 For y=0 To 599 r=Rand(y0.2,y0.4) g=r/2 b=r/2 ;First ;In ColorBuffer, draw with your lit version WritePixelFast x,y,(255 Shl 24)+(((r)) Shl 16)+(((g)) Shl 8)+(((b))),ImageBuffer(ColorBuffer) ;Then ;In GreyBuffer, draw the exact same, but make it dark, and maybe even grey! WritePixelFast x,y,(255 Shl 24)+(((r+g+b)/6) Shl 16)+(((r+g+b)/8) Shl 8)+(((r+g+b)/8)),ImageBuffer(GreyBuffer) Next UnlockBuffer ImageBuffer(ColorBuffer) UnlockBuffer ImageBuffer(GreyBuffer) SetBuffer BackBuffer() If (x Mod 20)=0 Cls Text 320,240,"Hang on, all this plotting takes a while! "+x,1,1 Flip EndIf Next Repeat SetBuffer BackBuffer() ;When displaying.. ;First draw Lit version to back. DrawImage ColorBuffer,0,0 ;Next shift GreyBuffer into Overlay Buffer (Note, if you're redrawing GreyBuffer each frame, you needn't do this step, and you can use GreyBuffer instead of OverlayBuffer SetBuffer ImageBuffer(OverlayBuffer) DrawImage Greybuffer,0,0 ;Then draw "Mask Color" circles whereever you want to see color Color 255,0,255 z=MouseY()/3 Oval MouseX()-(z/2),MouseY()-(z/4),z,z/2 For n=1 To 50 ang=Rand(0,360) Line 400,0,MouseX()+(Sin(ang)(z/2)),MouseY()+(Cos(ang)(z/4)) Next ;Then go back to the backbuffer, and draw the overlay over the color. SetBuffer BackBuffer() DrawImage OverlayBuffer,0,0 Flip Until KeyDown(1) --v

Comments
Monday, 18 June 2007, 08:59
shroom_monk	That's quite clever. Slight glitch though: as you are using MouseX()/MouseY() for every calculation involving the mouse, and these values change in the fraction of a second between calculations (if I'm moving my mouse very fast), not everything ends up where it should. This could be easily fixed by taking MouseX()/MouseY() at the beginning of each update stage, and putting them in variables that are used for the rest of that update. Other than that, it's great! Oh, except it's a bit slow...
Monday, 18 June 2007, 10:11
magicman	Thats rather nice jay. not sure when i would ever need it, but its is still quite nice.

Comments