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Topic: Blending colors (Read 2698 times) |
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Glen Murphy
 
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Blending colors
« on: Oct 30th, 2002, 10:06am » |
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The 'blend' function takes two colours as input, and blends them according to the alpha value you supply.
int blend(int org, int col, int alpha) {
// org is original colour
// col is colour to add
// alpha is a value between 0 and 255,
// where 0 makes 'col' completely opaque
int r1=(org&0x0000ff);
int g1=(org&0x00ff00);
int b1=(org&0xff0000);
int r2=(col&0x0000ff);
int g2=(col&0x00ff00);
int b2=(col&0xff0000);
int r3=(((alpha*(r1-r2)) >>8 )+r2)&0x000000ff;
int g3=(((alpha*(g1-g2)) >>8 )+g2)&0x0000ff00;
int b3=(((alpha*(b1-b2)) >>8 )+b2)&0x00ff0000;
return (r3)|(g3)|(b3);
}
// The following code shows an example of this
// in action. It uses a pixel buffer because
// background() can't seem to take an int value
// eg 0x00ff0000
int pix[] = new int[320*320];
void setup() {
size(320, 320);
for(int i=0; i<320*320; i++) {
pix[i] = 0xff0000;
}
}
void loop() {
for(int i=0; i<320*320; i++) {
pix[i] = blend(pix[i], 0x0000ff, 254);
setPixel(i%320, (int)(i/320), pix[i]);
}
}
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| « Last Edit: Oct 31st, 2002, 12:42am by Processing » |
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