How is this function actually applied in the context of this code. IE What does it do?

// == this is a function to swap values between two integer variables =====
void swapInt(int &a, int &b) {
int c = a;
a = b;
b = c;
}

It swaps the values of color1 and color2.

// values before executing swapInt()

color1 == BLUE
color2 == YELLOW

swapInt(color1,color2)

// values after executing swapInt()

color1 == YELLOW
color2 == BLUE

Hi Lee. I started my electronics career around  three months ago. Trying like mad to get me head around programming. robotBuilder and Will have been a great support and freely giving of their time and knowledge. Once I get to a level where I feel comfortable I am going to try and set up an ATMEGA chip to run independently of USB on breadboard powered by 2X9V batteries in parallel down through a 7805 IC to give me 5V. 

Cheers,

Davy.

Hi Mate. Been going over your last code. Printed it off and noted changes to effects as I change values. 

I have one area where I am confused. (One that I'm aware of anyway) ;-). 

How is this function actually applied in the context of this code. IE What does it do?

// == this is a function to swap values between two integer variables =====
void swapInt(int &a, int &b) {
int c = a;
a = b;
b = c;
}

I have attached entire code for reference point.

Cheers,

Davy.

#include <Adafruit_NeoPixel.h> //Indicates library is available for access.
#include <FastLED.h>           //Indicates library is available for access.

#define LED_PIN 4     //Arduino Ouput pin
#define NUM_LEDS 10  // Number of LEDS avaialble

#define BLACK  0  // Activates BLACK IE Switches led off.
#define RED    1  // Activates RED
#define GREEN  2  // Activates GREEN
#define BLUE   3  // Activates BLUE
#define YELLOW 4  // Activates YELLOW
#define PURPLE 5  // Activates PURPLE
#define GRAY   6  // Activates GRAY

CRGB leds; // []Indicates an array. In this case 10 LEDS.
// NUM_LEDS could also be expressed as ;.

CRGB colorList = {
                     {CRGB(0,0,0)},     // NO COLOR
                     {CRGB(0,255,0)},   // RED
                     {CRGB(255,0,0)},   // GREEN
                     {CRGB(0,0,255)},   // BLUE
                     {CRGB(255,255,0)}, // YELLOW
                     {CRGB(102,0,51)},  // PURPLE
                     {CRGB(51,51,0)},   // GRAY
                    };
//CRGB colorList =. Array assigning colours to colour list.
//Each entry requires opening and closing curly brackets,
//with RGB values in parenthesis. Comma to complete after closing curly bracket.
//Comma acts as seperator.
//Curly brackets indicate start and end of function or statement. 
//Must be used as a pair IE Opening and Closing {}.Highlighting
//one bracket in code will identify opposite bracket.
// Check that values in parenthesis align with colour nominated.

                  
// == this is a function to swap values between two integer variables  =====
void swapInt(int &a, int &b) {
  int c = a;
  a = b;
  b = c;
}


void setup() {
  Serial.begin(9600); // 
  FastLED.addLeds<WS2812, LED_PIN, GRB>(leds, NUM_LEDS);
  FastLED.setBrightness(100);
  // turn off all leds
  for (int ledNumber = 0; ledNumber < NUM_LEDS; ledNumber++) {
      leds = colorList;
  }
  FastLED.show();  // copy leds[] values to actual leds
}

int ledNumber2;   // working variable

int color1, color2;    // stores two colors
int loopCounter = 0;   // counts times loop() is repeated

void loop() {

  // decide what pair of colors to use for this loop() count
  if (loopCounter == 0){
    color1 = BLUE;
    color2 = RED;
  }

  if (loopCounter == 1){
    color1 = GREEN;
   color2 = YELLOW;
  }

  if (loopCounter == 2){
   color1 = PURPLE;
    color2 = GRAY;
  }

  // update loopCounter
  loopCounter = loopCounter + 1;
  if (loopCounter == 3){
    loopCounter = 0;        // reset counter
  }

  for (int ledNumber1 = 0; ledNumber1 < NUM_LEDS; ledNumber1++)  // for each led
  { 

    // swap colors half way to give bounce off each other effect
    if (ledNumber1 == 5){
      swapInt(color1,color2);
    }
    
    leds = colorList;
    ledNumber2 = 9 - ledNumber1;
    leds = colorList;
    FastLED.show();
    delay(100);
    leds = colorList; //turn off led
    leds = colorList; //turn off led
    FastLED.show();
    delay(0); //Time turned off.
  }

}

Thanks, gentlemen. I have been following along with this topic from the beginning. I even purchased a reel of neopixels to play with. Thanks very much to @robotBuilder and @Will for their help and instructions in how to efficiently program this project. Very interesting… “wasted” many afternoons working on this. But, at 76, my days are not exactly filled with pressing matters.  Now trying to port it to RPi using Python. Will be trying to use two strips running independently lighting up the lights. (Hopefully… I don’t have it working yet).

Good Wishes to you and yours,

Lee

Thanks Mate. Programme runs perfectly. Will spend next few days digesting learnings. 

Cheers,

Davy.

So the bouncing effect IE when one colour starts at 0 to 4 and second colour starts from 9 to 5 would look like this?

ledNumber1: 0 1 2 3 4 4 3 2 1 0
ledNumber2: 9 8 7 6 5 5 6 7 8 9

No. The colours just move all the way through each other. One left to right and the other right to left.

How would I add a function to this code to give the effect of the LEDs bouncing off each other without using attached pattern?

The fun part of programming is working this out yourself :)  That means learning more about programming. For example making use of the conditional statement  if (this is true) do X else do Y

The method I used below, to give the bounce effect, uses variables, color1 and color2 to hold the colour numbers and swap their values half way through the for loop. I added a swapInt function to perform the swap task.

I have also added a loopCounter variable to count how many times the main loop() is executed. This is used to swap the colours.  The pair of colour variables are changed three times after which the loopCounter is reset to repeat the colour pairs again.

I can't run the program so I just hope it behaves as I think it will.

#include <Adafruit_NeoPixel.h>
#include <FastLED.h>

#define LED_PIN 4
#define NUM_LEDS 10

#define BLACK  0
#define RED    1
#define GREEN  2
#define BLUE   3
#define YELLOW 4
#define PURPLE 5
#define GRAY   6

CRGB leds;

CRGB colorList = {
                     {CRGB(0,0,0)},     // NO COLOR
                     {CRGB(255,0,0)},   // RED
                     {CRGB(0,255,0)},   // GREEN
                     {CRGB(0,0,255)},   // BLUE
                     {CRGB(255,255,0)}, // YELLOW
                     {CRGB(102,0,51)},  // PURPLE
                     {CRGB(51,51,0)},   // GRAY
                    };

// == this is a function to swap values between two integer variables  =====
void swapInt(int &a, int &b) {
  int c = a;
  a = b;
  b = c;
}


void setup() {
  Serial.begin(9600);
  FastLED.addLeds<WS2812, LED_PIN, GRB>(leds, NUM_LEDS);
  FastLED.setBrightness(100);
  // turn off all leds
  for (int ledNumber = 0; ledNumber < NUM_LEDS; ledNumber++) {
      leds = colorList;
  }
  FastLED.show();  // copy leds[] values to actual leds
}

int ledNumber2;   // working variable

int color1, color2;    // stores two colors
int loopCounter = 0;   // counts times loop() is repeated

void loop() {

  // decide what pair of colors to use for this loop() count
  if (loopCounter == 0){
    color1 = RED;
    color2 = BLUE;
  }

  if (loopCounter == 1){
    color1 = GREEN;
    color2 = YELLOW;
  }

  if (loopCounter == 2){
    color1 = PURPLE;
    color2 = GRAY;
  }

  // update loopCounter
  loopCounter = loopCounter + 1;
  if (loopCounter == 3){
    loopCounter = 0;        // reset counter
  }

  for (int ledNumber1 = 0; ledNumber1 < NUM_LEDS; ledNumber1++)  // for each led
  { 

    // swap colors half way to give bounce off each other effect
    if (ledNumber1 == 5){
      swapInt(color1,color2);
    }
    
    leds = colorList;
    ledNumber2 = 9 - ledNumber1;
    leds = colorList;
    FastLED.show();
    delay(400);
    leds = colorList; //turn off led
    leds = colorList;
    FastLED.show();
    delay(400);
  }

}

Mate, further to my previous post....

With your last example you a mixing methods (look up table for values to use vs algorithm to generate those values). I would recommend that you learn to use algorithms. Lists and tables have a use but they aren't teaching you how to improve your programming.

For example if you want two different colours to pass each other you might think how to compute the second led position from the position of the led moving right.

ledNumber1: 0 1 2 3 4 5 6 7 8 9
ledNumber2: 9 8 7 6 5 4 3 2 1 0

Notice that ledNumber2 = 9 - ledNumber1

In this example the red moves left to right while the green moves right to left. This is repeated.

So the bouncing effect IE when one colour starts at 0 to 4 and second colour starts from 9 to 5 would look like this?

ledNumber1: 0 1 2 3 4 4 3 2 1 0
ledNumber2: 9 8 7 6 5 5 6 7 8 9

If so, how is this applied?

Thanks,

Davy.

Hi Mate thanks for this code. A lot easier to work with colours. One thing I'd like to ask;

How would I add a function to this code to give the effect of the LEDs bouncing off each other without using attached pattern? I have tried a few things but can only get them to run one way IE from led 5-9 and then restarting from 5 again.

Cheers,

Davy.

int patterns = {{1,0,0,0,0,0,0,0,0,2},
{0,1,0,0,0,0,0,0,2,0},
{0,0,1,0,0,0,0,2,0,0},
{0,0,0,1,0,0,2,0,0,0},
{0,0,0,0,1,2,0,0,0,0},
{0,0,0,0,1,2,0,0,0,0},
{0,0,0,1,0,0,2,0,0,0},
{0,0,1,0,0,0,0,2,0,0},
{0,1,0,0,0,0,0,0,2,0},
{1,0,0,0,0,0,0,0,0,2},
{0,1,0,0,0,0,0,0,2,0},
{0,0,1,0,0,0,0,2,0,0},
{0,0,0,1,0,0,2,0,0,0},
{0,0,0,0,1,2,0,0,0,0},
{0,0,0,0,1,2,0,0,0,0},
{0,0,0,1,0,0,2,0,0,0},
{0,0,1,0,0,0,0,2,0,0},
{0,1,0,0,0,0,0,0,2,0}};

#include <Adafruit_NeoPixel.h>
#include <FastLED.h>

#define LED_PIN 4
#define NUM_LEDS 10

#define BLACK  0
#define RED    1
#define GREEN  2
#define BLUE   3
#define YELLOW 4
#define PURPLE   5
#define GRAY 6
CRGB leds;

CRGB colorList = {
                     {CRGB(0,0,0)},     // NO COLOR
                     {CRGB(255,0,0)},   // RED
                     {CRGB(0,255,0)},   // GREEN
                     {CRGB(0,0,255)},   // BLUE
                     {CRGB(255,255,0)}, // YELLOW
                     {CRGB(102,0,51)},   // PURPLE
                     {CRGB(51,51,0)},   // GRAY
                    };

void setup() {
  Serial.begin(9600);
  FastLED.addLeds<WS2812, LED_PIN, RGB>(leds, NUM_LEDS);
  FastLED.setBrightness(100);
  // turn off all leds
  for (int ledNumber = 0; ledNumber < NUM_LEDS; ledNumber++) {
      leds = colorList;
  }
  FastLED.show();  // copy leds[] values to actual leds
}

int ledNumber2;   // working variable

void loop() {

      for (int ledNumber1 = 0; ledNumber1 < NUM_LEDS; ledNumber1++)  // for each led
      {       
        leds = colorList;
        ledNumber2 = 9 - ledNumber1;
        leds = colorList;
        FastLED.show();
        delay(400);
        leds = colorList; //turn off led
        leds = colorList;
        FastLED.show();
        delay(400);
      }

      
        for (int ledNumber1 = 0; ledNumber1 < NUM_LEDS; ledNumber1++)  // for each led

        {
         leds = colorList;
         ledNumber2 = 9 - ledNumber1;
         leds = colorList;
        FastLED.show();
        delay(400);
        leds = colorList; //turn off led
        leds = colorList;
        FastLED.show();
        delay(400);

       
      }
      
     for (int ledNumber1 = 0; ledNumber1 < NUM_LEDS; ledNumber1++)  // for each led 
{
  
         leds = colorList;
         ledNumber2 = 9 - ledNumber1;
         leds = colorList;
        FastLED.show();
        delay(400);
        leds = colorList; //turn off led
        leds = colorList;
        FastLED.show();
        delay(400);
}
}


        

https://www.youtube.com/watch?v=JpEFAXenTyY&t=1918s&ab_channel=DroneBotWorkshop

Neopixel demonstration starts around 25-00

Missed that one!  I didn't know you could buy individual addressable rgb leds or that Bill had covered the topic.  Making colour led displays just wasn't on my radar.