Here's the code I wrote:
```c++
#include <Adafruit_NeoPixel.h>
#ifdef __AVR__
#include <avr/power.h> // Required for 16 MHz Adafruit Trinket
#endif
int latchPin = 8;
int clockPin = 12;
int dataPin = 11;
int numOfRegisters = 2;
byte* registerState;
long effectId = 0;
long prevEffect = 0;
long effectRepeat = 0;
long effectSpeed = 30;
#define LED_PIN 2
#define LED_COUNT 24
Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);
void setup() {
#if defined(__AVR_ATtiny85__) && (F_CPU == 16000000)
clock_prescale_set(clock_div_1);
#endif
strip.begin(); // INITIALIZE NeoPixel strip object (REQUIRED)
strip.show(); // Turn OFF all pixels ASAP
strip.setBrightness(50); // Set BRIGHTNESS to about 1/5 (max = 255)
//Initialize array
registerState = new byte[numOfRegisters];
for (size_t i = 0; i < numOfRegisters; i++) {
registerState[i] = 0;
}
//set pins to output so you can control the shift register
pinMode(latchPin, OUTPUT);
pinMode(clockPin, OUTPUT);
pinMode(dataPin, OUTPUT);
}
void loop() {
do {
effectId = random(6);
} while (effectId == prevEffect);
prevEffect = effectId;
switch (effectId) {
case 0:
effectRepeat = random(1, 2);
break;
case 1:
effectRepeat = random(1, 2);
break;
case 3:
effectRepeat = random(1, 5);
break;
case 4:
effectRepeat = random(1, 2);
break;
case 5:
effectRepeat = random(1, 2);
break;
}
for (int i = 0; i < effectRepeat; i++) {
effectSpeed = random(10, 90);
switch (effectId) {
case 0:
effectA(effectSpeed);
break;
case 1:
effectB(effectSpeed);
break;
case 3:
effectC(effectSpeed);
break;
case 4:
effectD(effectSpeed);
break;
case 6:
effectE(effectSpeed);
break;
}
}
// Fill along the length of the strip in various colors...
colorWipe(strip.Color(255, 0, 0), 1); // Red
colorWipe(strip.Color( 0, 255, 0), 1); // Green
colorWipe(strip.Color( 0, 0, 255), 1); // Blue
// Do a theater marquee effect in various colors...
theaterChase(strip.Color(127, 127, 127), 1); // White, half brightness
theaterChase(strip.Color(127, 0, 0), 1); // Red, half brightness
theaterChase(strip.Color( 0, 0, 127), 1); // Blue, half brightness
rainbow(1); // Flowing rainbow cycle along the whole strip
theaterChaseRainbow(1); // Rainbow-enhanced theaterChase variant
}
void colorWipe(uint32_t color, int wait) {
for (int i=0; i<strip.numPixels(); i++) { // For each pixel in strip...
strip.setPixelColor(i, color); // Set pixel's color (in RAM)
strip.show(); // Update strip to match
delay(wait); // Pause for a moment
}
}
void theaterChase(uint32_t color, int wait) {
for (int a=0; a<10; a++) { // Repeat 10 times...
for (int b=0; b<3; b++) { // 'b' counts from 0 to 2...
strip.clear(); // Set all pixels in RAM to 0 (off)
// 'c' counts up from 'b' to end of strip in steps of 3...
for (int c=b; c<strip.numPixels(); c += 3) {
strip.setPixelColor(c, color); // Set pixel 'c' to value 'color'
}
strip.show(); // Update strip with new contents
delay(wait); // Pause for a moment
}
}
}
void rainbow(int wait) {
for (long firstPixelHue = 0; firstPixelHue < 5*65536; firstPixelHue += 256) {
for (int i=0; i<strip.numPixels(); i++) { // For each pixel in strip...
int pixelHue = firstPixelHue + (i * 65536L / strip.numPixels());
strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(pixelHue)));
}
strip.show(); // Update strip with new contents
delay(wait); // Pause for a moment
}
}
void theaterChaseRainbow(int wait) {
int firstPixelHue = 0; // First pixel starts at red (hue 0)
for (int a=0; a<30; a++) { // Repeat 30 times...
for (int b=0; b<3; b++) { // 'b' counts from 0 to 2...
strip.clear(); // Set all pixels in RAM to 0 (off)
// 'c' counts up from 'b' to end of strip in increments of 3...
for (int c=b; c<strip.numPixels(); c += 3) {
// hue of pixel 'c' is offset by an amount to make one full
// revolution of the color wheel (range 65536) along the length
// of the strip (strip.numPixels() steps):
int hue = firstPixelHue + c * 65536L / strip.numPixels();
uint32_t color = strip.gamma32(strip.ColorHSV(hue)); // hue -> RGB
strip.setPixelColor(c, color); // Set pixel 'c' to value 'color'
}
strip.show(); // Update strip with new contents
delay(wait); // Pause for a moment
firstPixelHue += 65536 / 90; // One cycle of color wheel over 90 frames
}
}
}
void effectA(int speed){
for (int i = 0; i < 16; i++) {
for (int k = i; k < 16; k++) {
regWrite(k, HIGH);
delay(speed);
regWrite(k, LOW);
}
regWrite(i, HIGH);
}
}
void effectB(int speed) {
for (int i = 15; i >= 0; i--) {
for (int k = 0; k < i; k++) {
regWrite(k, HIGH);
delay(speed);
regWrite(k, LOW);
}
regWrite(i, HIGH);
}
}
void effectC(int speed){
int prevI = 0;
for (int i = 0; i < 16; i++) {
regWrite(prevI, LOW);
regWrite(i, HIGH);
prevI = i;
delay(speed);
}
for (int i = 15; i >= 0; i--) {
regWrite(prevI, LOW);
regWrite(i, HIGH);
prevI = i;
delay(speed);
}
}
void effectD(int speed){
for (int i = 0; i < 8; i++) {
for (int k = i; k < 8; k++) {
regWrite(k, HIGH);
regWrite(15 - k, HIGH);
delay(speed);
regWrite(k, LOW);
regWrite(15 - k, LOW);
}
regWrite(i, HIGH);
regWrite(15 - i, HIGH);
}
}
void effectE(int speed) {
for (int i = 7; i >= 0; i--) {
for (int k = 0; k <= i; k++) {
regWrite(k, HIGH);
regWrite(15 - k, HIGH);
delay(speed);
regWrite(k, LOW);
regWrite(15 - k, LOW);
}
regWrite(i, HIGH);
regWrite(15 - i, HIGH);
}
}
void regWrite(int pin, bool state) {
//Determines register
int reg = pin / 8;
//Determines pin for actual register
int actualPin = pin - (8 * reg);
//Begin session
digitalWrite(latchPin, LOW);
for (int i = 0; i < numOfRegisters; i++) {
//Get actual states for register
byte* states = ®isterState[i];
//Update state
if (i == reg){
bitWrite(*states, actualPin, state);
}
//Write
shiftOut(dataPin, clockPin, MSBFIRST, *states);
}
//End session
digitalWrite(latchPin, HIGH);
}
```