Random colors from array

Question

Is it possible to assign a random color to a string of leds? I have a string of 10 WS2812 leds, and they can be any color I stated in the array With the FastLed lib a color can be a name.

colorLed = {Red, Blue, Green, Purple};

I would like to random pick a color for each led separate, not the whole string just on one color. It's not a problem is two or more leds have the same color.

I tried something like this: trying to assing a color to a number, and giving the led a random number. The code doesn't validate, it's not possible to combine an int with a random number (at least not the way I tried)

#include "FastLED.h"
#define NUM_LEDS 10

CRGB leds[NUM_LEDS];

#define DATA_PIN 2

long randNumber;
long randNumber0 = CRGB::Red;
long randNumber1 = CRGB::White;
long randNumber2 = CRGB::Blue;
long randNumber3 = CRGB::Red;
long randNumber4 = CRGB::White;
long randNumber5 = CRGB::Blue;
long randNumber6 = CRGB::Red;
long randNumber7 = CRGB::White;
long randNumber8 = CRGB::Blue;
long randNumber9 = CRGB::Red;

#define INTERVAL_MESSAGE1 5000

unsigned long time_1 = 0;

void setup() {
  FastLED.addLeds<WS2812B, DATA_PIN, GRB>(leds, NUM_LEDS);

  Serial.begin(9600);
}

void loop() {

  if (millis() >= time_1 + INTERVAL_MESSAGE1) {
    time_1 += INTERVAL_MESSAGE1;
    leds[0] =  randNumber.random(0,9);
    leds[1] =  randNumber.random(0,9);
    leds[2] =  randNumber.random(0,9);
    leds[3] =  randNumber.random(0,9);
    leds[4] =  randNumber.random(0,9);
    leds[5] =  randNumber.random(0,9);
    leds[6] =  randNumber.random(0,9);
    leds[7] =  randNumber.random(0,9);
    leds[8] =  randNumber.random(0,9);
    leds[9] =  randNumber.random(0,9);
    FastLED.show(55);
  }


}

score 0 · Answer 1 · edited Nov 20 '20 at 13:46

Assuming that you have 4 colors in your colorLed array, you could enumerate them and do something like:

# define MAX_COLORS 4    // Assuming you have 4 colors only

enum ColorList{
Red = 1,
Blue,
Green,
Purple
};

Then used them as a data type in a struct (simply because I love compartmentalising data into classes and data structures).

I've put together the following code. Please note that I've tested it on CodeLite for C++ and haven't tried it on an Arduino. However, I am sure that it will work just fine if you adapt it to your needs.

/* ColoPicker.cpp*/

#include <iostream>
#include <random>
#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <time.h>

using namespace std;

#define MAX_COLORS 4

char textOut[100];
int cycles;

string colorNames[4] = { "RED", "BLUE", "GREEN", "PURPLE" };

typedef enum { RED, BLUE, GREEN, PURPLE } ColorList;

struct ColorsGroup {
    ColorList colorCode;
    string name;
};

ColorsGroup colorLED[4];

// Methods
int random(int, int);
ColorList retrieveColor(int);
void fillColors(void);
void printColors(int);

void setup()
{

    fillColors();

    cycles = 0;
}

int main()
{
    cout << "********** Color picker *********" << endl;

    setup();

    while(cycles < 10) {

    fillColors();

    printColors(cycles);

    cycles++;
    
    }

    return 0;
}

// From: https://stackoverflow.com/questions/7560114/random-number-c-in-some-range
int random(int min, int max)
{
    static bool first = true;

    if(first) {
    srand(time(NULL));
    first = false;
    }

    return min + rand() % ((max + 1) - min);
}

void fillColors(void)
{
    for(int idx = 0; idx < MAX_COLORS; idx++) {

    ColorList newColor = retrieveColor(random(0, MAX_COLORS - 1));

    colorLED[idx].colorCode = newColor;
    colorLED[idx].name = colorNames[newColor];
    }
}

void printColors(int i)
{
    sprintf(textOut, "%d. colorLED >> ", i);

    cout << textOut ;
    
    for(int idx = 0; idx < MAX_COLORS; idx++) {

    const char* nameStr = colorLED[idx].name.c_str(); // or &colorLED[idx].name[0];

    sprintf(textOut, "%s[%d]",  nameStr, colorLED[idx].colorCode);  
    cout << textOut;
    
    if(idx <= MAX_COLORS-2){
        sprintf(textOut, ", ");
        cout << textOut;
    }else{
        cout << ";" << endl;
    }
    
    }
}

ColorList retrieveColor(int col)
{

    switch(col) {
        
    case 0:
    return RED;
    break;
    
    case 1:
    return BLUE;
    break;
    
    case 2:
    return GREEN;
    break;
    
    case 3:
    return PURPLE;
    break;

    default:
    return RED; // for the sake of completeness
    break;
    }
}

And the output looks like this:

Console Output for ColorPicker

Random colors from array

1 Answers1