RGB 32x32 LED grid programming

gistfile1.txt

// colorwheel demo for RGBmatrixPanel library.
// Renders a nice circle of hues on a 32x32 RGB LED matrix.

#include <Adafruit_GFX.h>   // Core graphics library
#include <RGBmatrixPanel.h> // Hardware-specific library
 
// If your 32x32 matrix has the SINGLE HEADER input,
// use this pinout:
#define CLK 8  // MUST be on PORTB!
#define OE  9
#define LAT 10
#define A   A0
#define B   A1
#define C   A2
#define D   A3
// If your matrix has the DOUBLE HEADER input, use:
//#define CLK 8  // MUST be on PORTB!
//#define LAT 9
//#define OE  10
//#define A   A3
//#define B   A2
//#define C   A1
//#define D   A0
RGBmatrixPanel matrix(A, B, C, D, CLK, LAT, OE, false);
int col;

void setup() {
  int      x, y, hue;
  float    dx, dy, d;
  uint8_t  sat, val;
  uint16_t c;

  matrix.begin();

  for(y=0; y < matrix.width(); y++) {
    dy = 15.5 - (float)y;
    for(x=0; x < matrix.height(); x++) {
      dx = 15.5 - (float)x;
      d  = dx * dx + dy * dy;
      if(d <= (16.5 * 16.5)) { // Inside the circle(ish)?
        hue = (int)((atan2(-dy, dx) + PI) * 1536.0 / (PI * 2.0));
        d = sqrt(d);
        if(d > 15.5) {
          // Do a little pseudo anti-aliasing along perimeter
          sat = 255;
          val = (int)((1.0 - (d - 15.5)) * 255.0 + 0.5);
        } else
        {
          // White at center
          sat = (int)(d / 15.5 * 255.0 + 0.5);
          val = 255;
        }
        c = matrix.ColorHSV(hue, sat, val, true);
      } else {
        c = 0;
      }
     // c = matrix.ColorHSV(0, 255, 100, true);

      matrix.drawPixel(x, y, matrix.Color444(10, 0, 0));
    }
  }
}

void loop() {
  // do nothing
 col++;
 col = col % 16;
 for(int y=0; y < matrix.width(); y++) {
          for(int x=0; x < matrix.height(); x++) {
            int xx = (x + col);
            int yy = (y + col);
            matrix.drawPixel(x, y, matrix.Color444(((xx) % 16)/2, ((xx + yy) % 16)/2, ((yy) % 16)/2));
            //matrix.drawPixel(x, y, matrix.Color444(5, 5, 5));  
        }
    }

}