step static method

void step(Float32List g, int? levels)

Partition a terrain into flat steps.

Float32List g The geometry's z-positions to modify with heightmap data. int levels The number of steps to divide the terrain into. Defaults to (g.length/2)^(1/4).

Implementation

static void step(Float32List g, int? levels) {
  int i = 0,
    j = 0,
    l = g.length;
  levels ??= (math.pow(l*0.5, 0.25)).floor();
  // Calculate the max, min, and avg values for each bucket
  int inc = (l / levels).floor();
  List<double> heights = List.filled(l,0);
  List<Map<String,double>> buckets = List.filled(levels, {});

  for (i = 0; i < l; i++) {
    heights[i] = g[i];
  }
  heights.sort((a, b){ return (a - b).toInt(); });
  for (i = 0; i < levels; i++) {
      // Bucket by population (bucket size) not range size
      List<double> subset = heights.sublist(i*inc, (i+1)*inc);
      double sum = 0;
      int bl = subset.length;
      for (j = 0; j < bl; j++) {
          sum += subset[j];
      }
      buckets[i] = {
        'min': subset[0],
        'max': subset[subset.length-1],
        'avg': sum / bl,
      };
  }

  // Set the height of each vertex to the average height of its bucket
  for (i = 0; i < l; i++) {
    final startHeight = g[i];
    for (j = 0; j < levels; j++) {
      if (startHeight >= buckets[j]['min']! && startHeight <= buckets[j]['max']!) {
        g[i] = buckets[j]['avg']!;
        break;
      }
    }
  }
}