CODEWITHSUNDEEP
c++openglcolors
user2803017
user2803017

Reputation: 19

How to create multiple colours based on many different ints

I would like to make a function that creates an unique color based on int variables. The problem is range of these variables (from 1 to 10 000).

So i have an array with 10 000 fields of which each has its own ID. And now i need to set color of each field based on that id;

void setColor(int ID); // set R G B

Any suggestions?

Upvotes: 0

Views: 282

Answers (3)

user2249683
user2249683

Reputation:

You can omit the table and build a hash function. A simple one is:

rgb(unsigned x) {
    b = x & 0xFF;
    x >>= 8
    g = x & 0xFF;
    x >>= 8
    r = x & 0xFF;
}

The distribution is not nice here: 2^24 - 10000 = 16767216

An alternative hash could calculate distributed = id * 2^24 / 10000.

Upvotes: 0

Neil Kirk
Neil Kirk

Reputation: 21813

The simplest solution is simply to convert the ID into a RGB value directly. It certainly won't result in a visually distinctive range of colours, however.

Upvotes: 0

Abhineet Prasad
Abhineet Prasad

Reputation: 1271

You have 10,000 possible input options, whereas 256 x 256 x 256 = 16 million output options. Assuming you want to vary RGB values equally, you can at max use 21 diff values for R,G,B as that would yield 21.5^3 ~ 10000.

So you need to take a step of 256/21 ~ 12 to serve your purpose.

So, basically my point is :

int       RGB value
1         0,0,0
2         0,0,12
3         0,0,24
.
..
22        0,0,253
23        0,12,0
.
.
.
10000     255,255,255

Upvotes: 4

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