Electric rain / static shock / thunder mountain

screenshot.png

sketch_130820a.pde

int COARSENESS = 4;
ArrayList vertices;

float bump(float val) {
  return val + random(-1.0, 1.0);
}

class Vertex {
  int x, y;
  float val, target;

  Vertex(int _x, int _y, float _val) {
    x = _x; y = _y; val = _val;
  }

  int off = COARSENESS / 2;
  void draw() {
    noStroke();
    if (val < 0.25) fill(0, abs(val * 255.0) % 256, 0);
    else if (val < 0.75) fill(0, 0, abs(val * 255.0) % 256);
    else fill(abs(val * 255.0) % 256, 0, 0);

    rect(x - off, y - off, COARSENESS, COARSENESS);
  }

  void mutate(Vertex north, Vertex south, Vertex east, Vertex west) {
    if (abs(target - val) < 0.5) {
      float vNorth = bump(north.val);
      float vSouth = bump(south.val);
      float vEast  = bump(east.val);
      float vWest  = bump(west.val);
      target = (vNorth + vSouth + vEast + vWest) / 4.0;
      val = target;
    } else {
      val += (target - val) / 2;
    }
  }
}

void setup() {
  frameRate(60);
  size(displayWidth, displayHeight);

  vertices = new ArrayList<Vertex>();
  int off = COARSENESS / 2;
  for (int x = 0; x < width; x += COARSENESS) {
    for (int y = 0; y < height; y += COARSENESS) {
      vertices.add(new Vertex(x+off, y+off, 1.0));
    }
  }

  strokeWeight(off);
}

void draw() {
  background(0);
  int nVertices = vertices.size();
  int rowSize = width / COARSENESS;
  int colSize = height / COARSENESS;
  for (int i = 0; i < nVertices; ++i) {
    Vertex v = (Vertex) vertices.get(i);
    int iNorth = i - rowSize; iNorth = iNorth < 0 ? i : iNorth;
    int iSouth = i + rowSize; iSouth = iSouth >= nVertices ? i : iSouth;
    int iEast  = i;
    if ((i + 1) % rowSize != 0) iEast = i + 1;
    if (i + 1 > nVertices) iEast = i;
    int iWest  = i;
    if ((i - 1) % rowSize != rowSize - 1) iWest = i - 1;
    if (i - 1 < 0) iWest = i;
    Vertex north = (Vertex) vertices.get(iNorth);
    Vertex south = (Vertex) vertices.get(iSouth);
    Vertex east  = (Vertex) vertices.get(iEast);
    Vertex west  = (Vertex) vertices.get(iWest);
    v.mutate(north, south, east, west);
//    print(String.format("%d => N: %d, S: %d, E: %d, W: %d [%.2f, %.2f]\n", i, iNorth, iSouth, iEast, iWest, v.val, v.target));
    v.draw();
  }
  println();
}