Atari colour warterfall effect
BlitzMax Forums/BlitzMax Beginners Area/Atari colour warterfall effect
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| hi guys, i am trying to recreate the atari logo colour watrerfall effect, (go see youtube for some vids), anyhoo i have a bmp logo in white (255,255,255) on black (0,0,0) what i want to do is get the white part of the logo to display the color warterfall, i have some ideas but i have had no sucksess yet, any help here will be greatfully receved. many thanks |
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| One way is to draw the waterfall color thing first, then draw the atari shape on top of it - the atari shape will have alpha/mask where you want the hole to appear, render it in maskblend or alphablend. |
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| i tryed that first of all it does work but its a bit cluncky and slow, i also tryed to create a strip of animation images but again it was slow and cluncky, i am sure it can be done in code rather than in pre rendered gfx. |
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| I guess i'd consider creating the Atari logo by defining the vertices for the shape in code, and then scrolling texture coordinates. Cheers Charlie |
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| ok with a bit of lateral thought, i have cracked it, i use a blank background image then recolor the pixsels by addressing them direct (a la pixmap), then i overlay a mask to create the final image, here is the code, it could do with tyding and i have to say its based on a number of other posts in the forums but the color cycling is all mine! you will need 2 images light.png is the solid background mask.png has the cutout to create the final effect. thanks for the help any comment let me know CODE: Strict Graphics 800,600 Global pixmap:TPixmap Global image:TImage=LoadImage("light.png") 'this is the background image Global mask:TImage=LoadImage("mask.png") ' this is the mask Global color:Int=1 Global c:Int=254 While Not KeyDown(KEY_ESCAPE) Cls pixmap=LockImage(image) Local P:Byte Ptr,x:Int,y:Int,w:Int,h:Int Local red:Int,Green:Int,Blue:Int,alpha:Int h=PixmapHeight(pixmap)-1 w=PixmapWidth(pixmap)-1 For y=1 To h For x=1 To w p=Pixmap.PixelPtr(x,y) Red = P[0] Green = p[1] Blue = p[2] Alpha = p[3] Select color Case 1 p[2]=c p[1]=0 p[0]=0 p[3]=255 Case 2 p[2]=0 p[1]=c p[0]=0 p[3]=255 Case 3 p[2]=0 p[1]=0 p[0]=c p[3]=255 Case 4 p[2]=c p[1]=c p[0]=c p[3]=255 End Select Next c=c-4 If c<1 Then c=255 color=color+1 If color=5 Then color=1 EndIf Next UnlockImage(image) DrawImage image,0,150 DrawImage mask,0,150 Flip Wend end |
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| I don't think re-plotting the waterfall every cycle is the most efficient way of doing this. With an animImage for your waterfall in the form of a rectangle not much bigger than your logo image, all you have to do is render your fully white "ATARI" logo, set the blend-mode to LIGHTBLEND* then draw the animated waterfall. The waterfall's parts that fall on the black background won't be visible (as they'll be black as well), only having the parts that do fall on the logo showing up. *After setting the LIGHTBLEND mode, anything that's drawn to the currently active buffer will be modulated by what is already in it, giving the visual phenomenon described above. |
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