perlin3d.cpp

struct Noise3D
{
  static const int size = 8;

  sf::mesh::RealVector3 gradients[size][size][size];

  float Drop(float dist)
  {
      float val = fabs (dist);

      if (val < 1)
      {
          return 1 - 3 * val * val + 2 * val * val * val;
      }
      else
      {
          return 0;
      }
  }

  sf::mesh::RealVector3 Gradient(int i, int j, int k)
  {
    i &= size - 1;
    j &= size - 1;
    k &= size - 1;

    return gradients[i][j][k];
  }

  sf::mesh::RealVector3 Omega(int i, int j, int k, sf::mesh::RealVector3 point)
  {
    return Gradient(i, j, k) * Drop(point.x()) * Drop(point.y()) * Drop(point.z());
  }

  sf::mesh::RealVector3 Noise(sf::mesh::RealVector3 point)
  {
    int floorX = (int)floor(point.x());
    int floorY = (int)floor(point.y());
    int floorZ = (int)floor(point.z());

    sf::mesh::RealVector3 sum = sf::mesh::RealVector3::Zero();

    for (int i = floorX; i < floorX + 2; i++)
    {
        for (int j = floorY; j < floorY + 2; j++)
        {
          for (int k = floorZ; k < floorZ + 2; k++)
          {
              sum += Omega(i, j, k, sf::mesh::RealVector3(point.x() - i, point.y()- j, point.z() - k));
          }
        }
    }

    return sum;
  }

  static double nextDouble() {

    return rand() / double (RAND_MAX);
  }

  Noise3D()
  {
    for (int i = 0; i < size; i++)
    {
      for (int j = 0; j < size; j++)
      {
        for (int k = 0; k < size; k++)
        {
            gradients[i][j][k] = sf::mesh::RealVector3((float)(2 * nextDouble() - 1),
                                                       (float)(2 * nextDouble() - 1),
                                                       (float)(2 * nextDouble() - 1));
        }
      }
    }
  }

  sf::mesh::RealVector3 get (const sf::mesh::RealVector3& thePoint)
  {
    return Noise (thePoint * size);
  }
};