singleSimplex2 method

double singleSimplex2(int seed, int x, int y)

Implementation

double singleSimplex2(int seed, int x, int y) {
  var t = (x + y) * _f2;
  final i = x + t.floor();
  final j = y + t.floor();

  t = (i + j) * _g2;

  final x0 = x - (i - t);
  final y0 = y - (j - t);

  final int i1;
  final int j1;
  if (x0 > y0) {
    i1 = 1;
    j1 = 0;
  } else {
    i1 = 0;
    j1 = 1;
  }

  final x1 = x0 - i1 + _g2;
  final y1 = y0 - j1 + _g2;
  final x2 = x0 - 1 + _f2;
  final y2 = y0 - 1 + _f2;
  final double n0;
  final double n1;
  final double n2;

  t = 0.5 - x0 * x0 - y0 * y0;

  if (t < 0) {
    n0 = .0;
  } else {
    t *= t;
    n0 = t * t * gradCoord2D(seed, i, j, x0, y0);
  }

  t = 0.5 - x1 * x1 - y1 * y1;

  if (t < 0) {
    n1 = .0;
  } else {
    t *= t;
    n1 = t * t * gradCoord2D(seed, i + i1, j + j1, x1, y1);
  }

  t = 0.5 - x2 * x2 - y2 * y2;

  if (t < 0) {
    n2 = .0;
  } else {
    t *= t;
    n2 = t * t * gradCoord2D(seed, i + 1, j + 1, x2, y2);
  }

  return 50 * (n0 + n1 + n2);
}