MODEDEF(140, DARKNESS, {
 for (int i = 6; i >= 0; i--) {
  for (int j = 0; j < 8; j++) {
   for (int k = 0; k < 8; k++) {
    SET(j, i + 1, k, GET(j, i, k));
   }
  }
 }
 for (int j = 0; j < 8; j++) {
  for (int k = 0; k < 8; k++) {
   SET(j, 0, k, false);
  }
 }
 byte newCount = random(2, 7);
 for (int i = 0; i < newCount; ++i) {
  int x = random(0, 8);
  int z = random(0, 8);
  SET(x, 0, z, true);
 }
});

// light
STATIC_MODEDEF({ c->light(); });

// planes
MODEDEF(
 100,
 {
  c->clear();
  REG[0] = 0;
  REG[1] = 1;
  REG[2] = 0;
 },
 {
  REG[0] += (REG[1] == 1) ? 1 : -1;
  if (REG[0] == 7 && (REG[1] == 1)) {
   REG[1] = 0;
  } else if (REG[0] == 0 && REG[1] == 0) {
   REG[1] = 1;
   REG[2] = ++(REG[2]) % 3;
 }
 c->clear();
 for (int i = 0; i < 8; i++)
  for (int j = 0; j < 8; j++)
   if (REG[2] == 0)
    SET(i, REG[0], j, true);
  else if (REG[2] == 1)
  SET(REG[0], i, j, true);
 else
  SET(i, j, REG[0], true);
 });


// spirals
MODEDEF(
 90,
{
 c->clear();
 REG[0] = 2;
 REG[1] = 0;
},
{
 // shift down & clear last layer
 for (int i = 6; i >= 0; i--) {
  for (int j = 0; j < 8; j++) {
   for (int k = 0; k < 8; k++) {
    SET(j, i + 1, k, GET(j, i, k));
   }
  }
 }
 for (int j = 0; j < 8; j++) {
  for (int k = 0; k < 8; k++) {
   c->set(j, 0, k, false);
  }
 }

 // draw new last layer
 byte p = REG[0] = ++(REG[0]) % 7;
 if (p == 0) {
  REG[1] = ((REG[1] == 0) ? 1 : 0);
 }