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); } }

Dharman · Accepted Answer · 2020-11-20 13:46:42Z

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

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