color from int to color?

Programming Questions

Chrisir

in Programming Questions • 3 years ago

Hello,

the color is given by r,g,b what gives us approx. 256*256*256 colors.

Let's assume I have an int "A" running from 0 to 16 700 000.

I now want this process to be shown as a color. So I first have to run the r-value from 0 to 256, then the g, then the b, then turn r to 1 and let g run from 0 to 256...

that's sound a little complicate. what is the formula for

value of A -> r,g,b

Thanks !

Greetings!

Chris

Replies(17)

cedrickie..

Re: color from int to col?

3 years ago

why not doing it like this ?

void setup() {
size(600,400);

}

int r,g,b;
void draw() {
r++;
if(r==255){
g++;
r=0;
}
if(g==255){
b++;
g=0;
}
if(b==255){
b++;
r=0;
g=0;
b=0;
}
background(r,g,b);

}

Chrisir

Re: Re: color from int to col?

3 years ago

Well, I can't convert A to r,g,b using this, can I?

joora8

Re: color from int to col?

3 years ago

It's maybe not needed to do this conversion, as ced and koo say.

Anyway, if you want to convert the int A to r,g,b, assuming A is between 0 (black) and 255*255*255 (white),

and if colors are in this order [xRGB] (bits: 00000000rrrrrrrrggggggggbbbbbbbb)

you can do this with bit-to-bit operations :

int B_MASK = 255;

int G_MASK = 255<<8; //65280

int R_MASK = 255<<16; //16711680

then :

r = (A & R_MASK)>>16;

g = (A & G_MASK)>>8;

b = A & B_MASK;

________________________

With maths, using / and % on A, I don't see exactly how to calculate it but possible.

Chrisir

Re: Re: color from int to col?

3 years ago

Hello,

This is surely the best answer - but color jumps (after every 256 steps I guess).

But I will use this first! Thanks

(it's i instead of A here)

int i=0;

int B_MASK = 255;
int G_MASK = 255<<8;
int R_MASK = 255<<16;

void setup() {
size(screen.width, screen.height,P2D);
}

void draw () {
fill (getColorFromInt(i));
// fill(i);
rect ( 10,10,101,101);
delay (2);
i++;
}

color getColorFromInt(int i) {

// then :
int r = i & R_MASK;
int g = i & G_MASK;
int b = i & B_MASK;

return (color(r,g,b));
}

Chrisir

Re: Re: color from int to col?

3 years ago

I just realize that you edited your post.

The new version doesn't work.

Stays black.

joora8

Re: Re: color from int to col?

3 years ago

Yes I edited because I forgot something.

This code (below) does the extraction perfectly, look at the console. But it's not color-continuous for the eye because of the gap (255 to 0) of each incrementation.

It's very slow with the delay because of the 256^3 different colors to run...

If you want something continuous, it's not the right way. What do you want?

int i=0;
int B_MASK = 255;
int G_MASK = 255<<8;
int R_MASK = 255<<16;
void setup() {
size(120, 120,P2D);
}
void draw () {
fill (getColorFromInt(i));
// fill(i);
rect ( 10,10,101,101);
delay (2);
i++;
}
color getColorFromInt(int i) {
int r = (i & R_MASK)>>16;
int g = (i & G_MASK)>>8;
int b = i & B_MASK;
println("r:"+r+" g:"+g+" b:"+b);
return color(r,g,b);
}

Anyway if you use processing colors, there already are the red() blue() and green() func:

int i=0;
void setup() {
size(120, 120,P2D);
}
void draw () {
fill (getColorFromInt(i));
rect ( 10,10,101,101);
delay (2);
i++;
}
color getColorFromInt(int i) {
int r = (int)red(i);
int g = (int)green(i);
int b = (int)blue(i);
println("r:"+r+" g:"+g+" b:"+b);
return color(r,g,b); // returns i + alpha=255...
}

But in this case, I don't see what you need...

kooogy

the processing 'color' type is just an int, so you can use your counter anywhere you'd otherwise use a colour, ie stroke() or fill().

http://processing.org/reference/color_.html
http://processing.org/reference/color_datatype.html

Chrisir

Re: Re: color from int to col?

3 years ago

I think that only returns gray-values.

See code above with uncommented line....

blindfish

Re: color from int to col?

3 years ago

I'd never tried outputting the int value of a colour. The following might prove interesting:

void setup() {
size(100,100);
color foo = color(255,0,0);
int bar = int(foo);
println(bar);
fill(-65536);
rect(0,0,width,height);
}

Looks like colours are represented by negative ints from -1 to -16777216... or maybe not?

kooogy

Re: Re: color from int to col?

3 years ago

the top 8 bits is the alpha channel, and printing this as a signed number means it's large and -ve

this also explains why fill(i) thing above doesn't look like it works - for values < 2^24 the alpha is 0 so you can't see the colour.

change it to fill(0xff000000 + i) and you'll see it, very blue for the first 255 loops, gradually more yellow...

and also because for ints < 255 it uses this form:

color(gray);

which will only give you greys.

PhiLho

Re: color from int to col?

3 years ago

I think that only returns gray-values.

No. color() works for gray values and colors. With three parameters, it does exactly what you want, making a color out of r, g, b.
And with an int, eg. 0xFFAABBCC, it also does color.

joora8

Re: color from int to col?

3 years ago

exact...

I think he didn't ask the good question.

I guess he wants to get a continuous range of colors in a loop (draw loop?). Is it right?

If yes, maybe you just want to change the hue?

PhiLho

Re: color from int to color?

3 years ago

Yes, I even less understand the remark as color above was used this way...
" color jumps (after every 256 steps I guess)"
That's the way RGB works. To have more continuous transitions, as suggested by joora8, you have to switch to HSB mode and walk these values (hue, saturation, brightness) instead. You might need to go backward one loop out of two: eg. increasing hue, then changing brightness, and decreasing hue, etc. to avoid jumps. Will still take some time to walk the 16 millions colors... (but steps, and even ranges can be changed).

blindfish

Re: color from int to color?

3 years ago

Will still take some time to walk the 16 millions colors

Indeed... Depending on the rate of change people may not be looking at it long enough to perceive any noticeable difference in the colour, perhaps rendering the whole process a little futile. You'd do well to find a mapping that will result in discernible changes over a relatively short time: obviously depends somewhat on context, but generally speaking people have rather short attention spans these days. Just something to consider ;)

Chrisir

Re: color from int to color?

3 years ago

Hello,

thanks to everybody who helped me with this!

Thanks!

Greetings, Chrisir

Ghettokon

Re: color from int to color?

2 years ago

You might check this out, pretty cool, He has all the color gradation code figured out!

http://www.krazydad.com/makecolors.php

Chrisir

Re: color from int to color?

2 years ago

Thank you so much for coming back to me...

awesome...

Thanks!

Chrisir

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