NeoMatrix Rainbow Effect

sketch.ino

#include <Adafruit_GFX.h>
#include <Adafruit_NeoMatrix.h>
#include <Adafruit_NeoPixel.h>

#define PIN 6

Adafruit_NeoMatrix matrix = Adafruit_NeoMatrix(32, 8, PIN,
  NEO_MATRIX_TOP    + NEO_MATRIX_LEFT +
  NEO_MATRIX_COLUMNS + NEO_MATRIX_ZIGZAG,
  NEO_GRB            + NEO_KHZ800);

void setup() {
  matrix.begin();
  matrix.setBrightness(30);
  matrix.clear();
}

void loop() {
  rainbowCycle();
}

void rainbowCycle() {
  uint16_t i;
 
  for(i = 0; i < 256; i++) {
    for(int x = 0; x < matrix.width(); x++) {
      for(int y = 0; y < matrix.height(); y++) {
        matrix.drawPixel(x, y, Wheel((((x+y) * 256 / (8*32) + i) & 255)));
      }
    }
    matrix.show();
    delay(3);
  }
}
 
// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.
uint32_t Wheel(byte WheelPos) {
  if(WheelPos < 85) {
   return matrix.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
  } else if(WheelPos < 170) {
   WheelPos -= 85;
   return matrix.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  } else {
   WheelPos -= 170;
   return matrix.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
}