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Topic: brightness fade (Read 1232 times) |
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LigaMainz
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brightness fade
« on: Sep 13th, 2003, 2:11am » |
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hi. i am just checking bit-wise image calculating.
i made a brightness/darkness-fade and now i am wondering if there is any better/faster way to do this.
Especially for the lines of code where i check if the single colors are larger than 255 or smaller than 0 there should be a more elegant way.
Code:
int darkenPixel(int org, int step){
int r1=(org & 0xff0000) - (step << 16);
int g1=(org & 0x00ff00) - (step << 8) ;
int b1=(org & 0x0000ff) - (step) ;
if(r1 < 0x000000) r1 = 0x000000;
if(g1 < 0x000000) g1 = 0x000000;
if(b1 < 0x000000) b1 = 0x000000;
return (( r1 ) | ( g1 ) | b1 ) | 0xff000000;
}
int brightenPixel(int org, int step){
int r1=(org & 0xff0000)+ (step << 16);
int g1=(org & 0x00ff00)+ (step << 8) ;
int b1=(org & 0x0000ff)+ (step) ;
if(r1 > 0xff0000) r1 = 0xff0000;
if(g1 > 0x00ff00) g1 = 0x00ff00;
if(b1 > 0x0000ff) b1 = 0x0000ff;
return (( r1 ) | ( g1 ) | b1 ) | 0xff000000;
}
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And here the link:
http://www.say-nono.com/main/sketchbook/index.php?file=brightness
Vince
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LigaMainz
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Re: brightness fade
« Reply #1 on: Sep 13th, 2003, 3:45am » |
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ok.
i think i found the best and most flexible way.
It isn't my code but i think it may be useful for other beginners like me to check bitwise image-calculating.
Code:
int colorFade(int org, int mix, float percent){
// seperate the single color values of the original color by bitshifting
int r1=(org & 0xff0000)>>16;
int g1=(org & 0x00ff00)>>8;
int b1=(org & 0x0000ff);
// seperate the single color values of the mixcolor by bitshifting
int r2=(mix & 0xff0000)>>16;
int g2=(mix & 0x00ff00)>>8;
int b2=(mix & 0x0000ff);
// calculate the difference between the orignial color and the mixingcolor
// multiplicate this value with the fadevalue and add the result to the original color
int r3=(int)((r2-r1)*percent) + r1;
int g3=(int)((g2-g1)*percent) + g1;
int b3=(int)((b2-b1)*percent) + b1;
// compose the three colors again by bitshifting
return (( r3<<16 ) | ( g3<<8 ) | b3 ) | 0xff000000;
}
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I think i saw a similar piece of code in this very beautiful example by zevan:
http://www.shapevent.com/proc/diag/
He refers to http://www.bodytag.org.
this is my example:
http://www.say-nono.com/main/sketchbook/index.php?file=colorfade
(Is there a better way than this?)
Vince
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