Funky Lines 8x8 Matrix

// Funky Clouds 2014
// www.stefan-petrick.de/wordpress_beta

#include <FastLED.h>

// Matrix dimensions

const uint8_t WIDTH  = 8;
const uint8_t HEIGHT = 8;

// LED stuff

#define LED_PIN     5
#define COLOR_ORDER GRB
#define CHIPSET     WS2812B
#define BRIGHTNESS  80
#define NUM_LEDS (WIDTH * HEIGHT)
CRGB leds[NUM_LEDS];

// Timer stuff (Oszillators)

struct timer {unsigned long takt; unsigned long lastMillis; unsigned long count; int delta; byte up; byte down;};
// Always set the following number right - If you set a timer,
// you have to set sensfull limits in the setup part
timer multiTimer[5];

int timers = sizeof(multiTimer) / sizeof(multiTimer[0]);

void setup() {

  FastLED.addLeds<CHIPSET, LED_PIN, COLOR_ORDER>(leds, NUM_LEDS).setCorrection(SMD5050);
  FastLED.setBrightness(BRIGHTNESS);

  // set all counting directions positive for the beginning
  for (int i = 0; i < timers; i++) multiTimer[i].delta = 1;

  // set range (up/down), speed (takt=ms between steps) and starting point of all oszillators

  multiTimer[0].takt=  31;     //x1
  multiTimer[0].up = WIDTH - 1;
  multiTimer[0].down = 0;
  multiTimer[0].count = 0;

  multiTimer[1].takt=  37;     //y1
  multiTimer[1].up = HEIGHT - 1;
  multiTimer[1].down = 0;
  multiTimer[1].count = 0;

  multiTimer[2].takt=  15;      //color
  multiTimer[2].up = 255;
  multiTimer[2].down = 0;
  multiTimer[2].count = 0;

  multiTimer[3].takt=  45;     //x2
  multiTimer[3].up = WIDTH - 1;
  multiTimer[3].down = 0;
  multiTimer[3].count = 0;

  multiTimer[4].takt=  57;     //y2
  multiTimer[4].up = HEIGHT - 1;
  multiTimer[4].down = 0;
  multiTimer[4].count = 0;
}

void loop()
{
  // manage the Oszillators
  UpdateTimers();

  // draw just a line defined by 5 oszillators
  Line(
    multiTimer[3].count,  // x1
    multiTimer[4].count,  // y1
    multiTimer[0].count,  // x2
    multiTimer[1].count,  // y2
    multiTimer[2].count); // color

  // manipulate the screen buffer
  // with fixed parameters (could be oszillators too)
  // center x, y, radius, scale color down
  // --> affects always a square with an odd length
  Spiral(3,3,3,128);
//  Spiral(4,1,2,128);
  // why not several times?!
//  Spiral(8,3,3,128);
//  Spiral(5,12,5,128);

  // increase the contrast
  DimmAll(200);

//  FastLED.delay(20);
  // done.
  FastLED.show();

}


// finds the right index for my S matrix
int XY(int x, int y) {
  if(y > HEIGHT) { y = HEIGHT; }
  if(y < 0) { y = 0; }
  if(x > WIDTH) { x = WIDTH;}
  if(x < 0) { x = 0; }
  return (x * (WIDTH) + y);
}

// counts all variables with different speeds linear up and down
void UpdateTimers()
{
  unsigned long now=millis();
  for (int i=0; i < timers; i++)
  {
    while (now-multiTimer[i].lastMillis >= multiTimer[i].takt)
    {
      multiTimer[i].lastMillis += multiTimer[i].takt;
      multiTimer[i].count = multiTimer[i].count + multiTimer[i].delta;
      if ((multiTimer[i].count == multiTimer[i].up) || (multiTimer[i].count == multiTimer[i].down))
      {
        multiTimer[i].delta = -multiTimer[i].delta;
      }
    }
  }
}

// fade the image buffer arround
// x, y: center   r: radius   dimm: fade down
void Spiral(int x,int y, int r, byte dimm) {
  for(int d = r; d >= 0; d--) {
    for(int i = x-d; i <= x+d; i++) {
       leds[XY(i,y-d)] += leds[XY(i+1,y-d)];
       leds[XY(i,y-d)].nscale8( dimm );}
    for(int i = y-d; i <= y+d; i++) {
       leds[XY(x+d,i)] += leds[XY(x+d,i+1)];
       leds[XY(x+d,i)].nscale8( dimm );}
    for(int i = x+d; i >= x-d; i--) {
       leds[XY(i,y+d)] += leds[XY(i-1,y+d)];
       leds[XY(i,y+d)].nscale8( dimm );}
    for(int i = y+d; i >= y-d; i--) {
       leds[XY(x-d,i)] += leds[XY(x-d,i-1)];
       leds[XY(x-d,i)].nscale8( dimm );}
  }
}

// Bresenham line
void Line(int x0, int y0, int x1, int y1, byte color)
{
  int dx =  abs(x1-x0), sx = x0<x1 ? 1 : -1;
  int dy = -abs(y1-y0), sy = y0<y1 ? 1 : -1;
  int err = dx+dy, e2;
  for(;;){
    leds[XY(x0, y0)] += CHSV(color, 255, 255);
    if (x0==x1 && y0==y1) break;
    e2 = 2*err;
    if (e2 > dy) { err += dy; x0 += sx; }
    if (e2 < dx) { err += dx; y0 += sy; }
  }
}

void DimmAll(byte value)
{
  for(int i = 0; i < NUM_LEDS; i++)
  {
    leds[i].nscale8(value);
  }
}