Colour fading problem

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Socoder -> Blitz -> Colour fading problem
Fri, 29 Dec 2006, 16:32
mike_g	Hey peeps. I have been having a problem with fading colours to black when the rgb is all on one number. I made a demo prog to illustrate this below. This works but only when in grey. Const red_fade = (5 Shl 16) Const green_fade = (5 Shl 8) Const blue_fade = 5 colour = 255+(255 Shl 8)+(255 Shl 16) While Not KeyHit(1) Cls ;DRAW A RECT IN CURRENT COLOUR For x = 1 To 100 For y = 1 To 100 WritePixel x, y, colour Next Next ;FADE THE COLOUR If (colour Shr 16) > 5 Then colour = colour - red_fade If ((colour Shr 8) Mod 255) > 5 Then colour = colour - green_fade If (colour Mod 255) > 5 Then colour = colour - blue_fade Flip Wend --v If you change the first line of code to: Const red_fade = (3 Shl 16) --v you will see what I mean. The colours become bright all of a sudden when the red fades below 0 in the red section of the int and starts switching on bits in the other colours section. I thought this code would have worked, albeit slowly. It doesent though anyone know what im doing wrong?
Fri, 29 Dec 2006, 17:00
Jayenkai	Is there any real reason you can't do it this way, instead? (ie, keeping hold of RGB values, reducing those, then setting the colour with them). Graphics 640,480,32,2 SetBuffer BackBuffer() ; Sorry, my PC's too slow to do it without WritePixelFast ;) Red=255:Green=255:Blue=255 Const Red_Fade=2 Const Green_Fade=3 Const Blue_Fade=4 While Not KeyHit(1) Cls ;DRAW A RECT IN CURRENT COLOUR LockBuffer BackBuffer() For x = 1 To 100 For y = 1 To 100 WritePixelFast x, y, colour Next Next UnlockBuffer BackBuffer() ;FADE THE COLOUR Red=Red-Red_Fade:If Red<0 Then Red=0 Green=Green-Green_Fade:If Green<0 Then Green=0 Blue=Blue-Blue_Fade:If Blue<0 Then Blue=0 colour = Blue+(Green Shl 8)+(Red Shl 16) +(255 Shl 24) ; Don't forget alpha :) Flip Wend --v -=-=- ''Load, Next List!''
Fri, 29 Dec 2006, 17:23
mike_g	Thanks. That seems to work nicely