c# - 中点位移算法 - 奇怪的结果

Question

出于学习目的，我正在编写自己的中点位移算法，我决定以自己的方式实现它，看看我是否 1) 能够理解该算法，以及 2) 看看我是否可以根据自己的喜好修改它。

这里是生成分形的代码:

 public void Generate(Double rg, int size)
    {
        Random rand = new Random();
        int min = -127;
        int max = 128;

        // Starting points of the rectangle
        MDP_Point s1 = new MDP_Point(0, 0, rand.Next(min, max));
        MDP_Point s2 = new MDP_Point(size, 0, rand.Next(min, max));
        MDP_Point s3 = new MDP_Point(size, size, rand.Next(min, max));
        MDP_Point s4 = new MDP_Point(0, size, rand.Next(min, max));

        // Lists containing the rectangles
        List<MDP_Rect> newRect = new List<MDP_Rect>();  // Newly created rectangles
        List<MDP_Rect> oldRect = new List<MDP_Rect>();  // Rectangles being divided


        // Starting rectangle is added to the list
        oldRect.Add(new MDP_Rect(s1, s2, s3, s4));

        // Distance between 2 points in a rectangle
        int h = size;

        while (h > 1)
        {
            foreach (MDP_Rect r in oldRect)
            {
                // Middle points of rectangle segments
                MDP_Point m1 = new MDP_Point();
                MDP_Point m2 = new MDP_Point();
                MDP_Point m3 = new MDP_Point();
                MDP_Point m4 = new MDP_Point();
                // Middle point of rectangle
                MDP_Point mm = new MDP_Point();

                m1.x = (r.C1.x + r.C2.x) / 2;
                m1.y = (r.C1.y + r.C2.y) / 2;
                m1.z = ((r.C1.z + r.C2.z) / 2) +(rand.Next(min, max) * rg);

                m2.x = (r.C2.x + r.C3.x) / 2;
                m2.y = (r.C2.y + r.C3.y) / 2;
                m2.z = ((r.C2.z + r.C3.z) / 2) +(rand.Next(min, max) * rg);

                m3.x = (r.C3.x + r.C4.x) / 2;
                m3.y = (r.C3.y + r.C4.y) / 2;
                m3.z = ((r.C3.z + r.C4.z) / 2) +(rand.Next(min, max) * rg);

                m4.x = (r.C1.x + r.C4.x) / 2;
                m4.y = (r.C1.y + r.C4.y) / 2;
                m4.z = ((r.C1.z + r.C4.z) / 2) + (rand.Next(min, max) * rg);

                mm.x = (r.C1.x + r.C2.x + r.C3.x + r.C4.x) / 4;
                mm.y = (r.C1.y + r.C2.y + r.C3.y + r.C4.y) / 4;
                mm.z = ((r.C1.z + r.C2.z + r.C3.z + r.C4.z) / 4) + (rand.Next(min, max) * rg);

                newRect.Add(new MDP_Rect(r.C1, m1, mm, m4));
                newRect.Add(new MDP_Rect(m1, r.C2, m2, mm));
                newRect.Add(new MDP_Rect(mm, m2, r.C3, m3));
                newRect.Add(new MDP_Rect(m4, mm, m3, r.C4));
            }


            oldRect.Clear();
            oldRect = new List<MDP_Rect>(newRect);
            newRect.Clear();
            h /= 2;
        }

        List<MDP_Rect> sorted = new List<MDP_Rect>();
        sorted = oldRect.OrderBy(y => y.C1.y).ThenBy(x => x.C1.x).ToList();

        List<MDP_Point> mapArray = new List<MDP_Point>();
        mapArray.AddRange(CreateArray(sorted));

        CreateImage(size, mapArray, rg);
    }

MDP_Point 仅包含 x、y 和 z 值MDP_Rectangle 包含4个点，创建一个矩形

CreateArray() 方法仅采用有序的矩形列表并以正确的顺序输出和点列表以创建图像。

创建数组():

        private List<MDP_Point> CreateArray(List<MDP_Rect> lRect)
    {
        List<MDP_Point> p = new List<MDP_Point>();

        int size = (int)Math.Sqrt(lRect.Count);

        int i = 0;
        foreach (MDP_Rect r in lRect)
        {
            p.Add(new MDP_Point((int)r.C1.x, (int)r.C1.y, (int)r.C1.z));

            if (i > 0 && i % size == size - 1)
            {
                p.Add(new MDP_Point((int)r.C2.x, (int)r.C2.y, (int)r.C2.z));
            }

            i++;
        }

        for (int a = 0; a < size; a++)
        {
            p.Add(new MDP_Point((int)lRect[(size * size - size) + a].C4.x,
                (int)lRect[(size * size - size) + a].C4.y,
                (int)lRect[(size * size - size) + a].C4.z));

            if (a > 0 && a % size == size - 1)
            {
                p.Add(new MDP_Point((int)lRect[(size * size - size) + a].C3.x,
                    (int)lRect[(size * size - size) + a].C3.y,
                    (int)lRect[(size * size - size) + a].C3.z));
            }
        }

        return p;
    }

这是创建图像的方法:

        private void CreateImage(int size, List<MDP_Point> arr, double roughness)
    {
        Bitmap map = new Bitmap(size, size);

        int ver = 0;
        for (int i = 0; i < map.Height; i++)
        {
            for (int n = 0; n < map.Width; n++ )
            {
                int h = (int)arr[ver].z + 127;
                if (h < 0)
                {
                    h = 0;
                }
                else if (h > 255)
                {
                    h = 255 ;
                }
                Color c = Color.FromArgb(h, h, h);

                //map.SetPixel(n, i, c);
                map.SetPixel(i, n, c);
                ver++;
            }
        }

        Bitmap m = new Bitmap(map);
        bool saved = true;
        int num = 0;

        while (saved)
        {
            if (File.Exists("map_S" + size + "_R" + roughness + "_" + num + ".png"))
            {
                num++;
            }
            else
            {
                m.Save("map_S" + size + "_R" + roughness + "_" + num + ".png", System.Drawing.Imaging.ImageFormat.Png);
                saved = false;
            }
        }

        map.Dispose();
        m.Dispose();
    }

任何低于 0 的值都设置为 0 而任何高于 255 的值都设置为 255 的事实可能是一个大问题....不知道该怎么做。

这是代码生成的图像:尺码:1024粗糙度:0.5

最明显的问题是对角“脊线”和那里的平铺外观。

在这一点上，我不确定如何解决这个问题以使其看起来更自然。有什么想法吗？

Answer 1

在这里，我认为部分问题是您使用 255 和 0 对 h 变量进行了黑客攻击。我尝试使用以下代码:

int h = (int) arr[ver].z;
if (h < 0)
{
    h = Math.Abs(h);
}
while(h > 255)
{
    h -= 255;
}

在我的电脑上，结果是:

当我使用时:

int h = (int) arr[ver].z + 127;

请注意，我只需要创建一个测试 MDP_Point 类和 MDP_Rect 来测试这个...