Ballz.GameSession.World.Terrain.UpdateTerrain C# (CSharp) Method

        private void UpdateTerrain(int minY, int minX, int maxX)
        {
            minY = Math.Max(0, minY);
            
            // For every column check whether there is air below sand so that the latter moves downwards
            for (int x = minX; x < maxX; ++x)
            {
                int lowestAirPosition = height;
                for (int y = minY; y < height; ++y)
                {
                    TerrainType cur = PublicShape.TerrainBitmap[x, y];

                    //PublicShape.TerrainBitmap[x, y] = TerrainType.Air;

                    if (cur == TerrainType.Air)
                    {
                        if (lowestAirPosition == height)
                        {
                            lowestAirPosition = y;
                        }
                    }
                    else if (cur == TerrainType.Sand)
                    {
                        if (lowestAirPosition < height)
                        {
                            // Fill lowest air with sand
                            PublicShape.TerrainBitmap[x, lowestAirPosition] = TerrainType.Sand;

                            ++lowestAirPosition;

                            // This position is now air
                            PublicShape.TerrainBitmap[x, y] = TerrainType.Air;
                        }
                    }
                    else
                    {
                        // Reset
                        lowestAirPosition = height;
                    }
                }
            }
         
        }