Occlusion Culling Angle Check Helper

ChunkOcclusion.cs

public struct AngleRange {
  const float HalfPi = MathF.PI * 0.5f;
  
  public float Min, Max;
  
  public AngleRange(int run, int rise) {
    Min = MathF.Atan2(rise - 1, run + 1).Clamp(0, HalfPi);
    Max = MathF.Atan2(rise + 1, run - 1).Clamp(0, HalfPi);
  }
  
  public bool IsEmpty => Max <= Min;
  
  public static AngleRange Full =>
    new AngleRange { Min = 0, Max = MathF.PI * 0.5f };
  
  public static AngleRange Intersect(in AngleRange a, in AngleRange b) =>
    new AngleRange { Min = MathF.Max(a.Min, b.Min), Max = MathF.Min(a.Max, b.Max) };

  public static AngleRange Union(in AngleRange a, in AngleRange b) =>
    new() { Min = MathF.Min(a.Min, b.Min), Max = MathF.Max(a.Max, b.Max) };
}

public struct Angles {
  public AngleRange XY;
  public AngleRange YZ;
  public AngleRange XZ;
  
  public Angles(int dx, int dy, int dz) {
    dx = dx.Abs();
    dy = dy.Abs();
    dz = dz.Abs();
    XY = new (dx, dy);
    YZ = new (dy, dz);
    XZ = new (dx, dz);
  }
  
  public bool IsEmpty =>
    XY.IsEmpty || YZ.IsEmpty || XZ.IsEmpty;
  
  public static Angles Full => new Angles {
    XY = AngleRange.Full,
    YZ = AngleRange.Full,
    XZ = AngleRange.Full
  };
  
  public static Angles Intersect(in Angles a, in Angles b) => new Angles {
    XY = AngleRange.Intersect(a.XY, b.XY),
    YZ = AngleRange.Intersect(a.YZ, b.YZ),
    XZ = AngleRange.Intersect(a.XZ, b.XZ),
  };
  
  public static Angles Union(in Angles a, in Angles b) => new Angles {
    XY = AngleRange.Union(a.XY, b.XY),
    YZ = AngleRange.Union(a.YZ, b.YZ),
    XZ = AngleRange.Union(a.XZ, b.XZ),
  };
}