使用等离子体样式分形生成高度图期间的伪影

我今天花了几个小时研究如何生成随机地形，在阅读了等离子体分形（中点位移和菱形平方算法）后，我决定尝试实现一个。事实上，我的结果并不可怕，但我有这些可怕的方形/线条/网格型文物，我似乎无法摆脱！

当渲染为灰度图像时，我的高度图看起来像：高度图http://sphotos-d.ak.fbcdn.net/hphotos-ak-ash3/535816_10151739010123327_225111175_n.jpg

显然，这涉及到相当多的代码，但我会尽量发布只相关的内容。例如，我还没有发布将其转化为纹理的代码，但不用担心，我已经尝试过用平滑的梯度填充我的高度数组，纹理效果很好：）

我首先将地图的四个角设置为0到1之间的随机值，然后开始递归位移算法：

    public void GenerateTerrainLayer()
    {  
        //set the four corners of the map to have random values
        TerrainData[0, 0] = (float)RandomGenerator.NextDouble();
        TerrainData[GenSize, 0] = (float)RandomGenerator.NextDouble();
        TerrainData[0, GenSize] = (float)RandomGenerator.NextDouble();
        TerrainData[GenSize, GenSize] = (float)RandomGenerator.NextDouble();
        //begin midpoint displacement algorithm...
        MidPointDisplace(new Vector2_I(0, 0), new Vector2_I(GenSize, 0), new Vector2_I(0, GenSize), new Vector2_I(GenSize, GenSize));
    }

TerrainData只是一个浮动的2D数组*。Vector2_I只是我自己的整数向量类。最后四个函数是MidPointDisplace，它是递归函数，CalculateTerrainPointData，它平均2个数据值并添加一些噪声，CalculateTrainPointData2，它平均了4个数据值，并添加了一些噪声，具有略高的标度值（仅用于中心点），最后是我的噪声函数，atm只是一些随机噪声，而不是像perlin等那样的真实噪声。它们看起来像这样：

   private void MidPointDisplace(Vector2_I topleft, Vector2_I topright, Vector2_I bottomleft, Vector2_I bottomright)
    {
        //check size of square working on.. if its shorter than a certain amount stop the algo, we've done enough
        if (topright.X - topleft.X < DisplacementMaxLOD)
        {
            return;
        }

        //calculate the positions of all the middle points for the square that has been passed to the function
        Vector2_I MidLeft, MidRight, MidTop, MidBottom, Center;
        MidLeft.X = topleft.X;
        MidLeft.Y = topleft.Y + ((bottomleft.Y - topleft.Y) / 2);
        MidRight.X = topright.X;
        MidRight.Y = topright.Y + ((bottomright.Y - topright.Y) / 2);
        MidTop.X = topleft.X + ((topright.X - topleft.X) / 2);
        MidTop.Y = topleft.Y;
        MidBottom.X = bottomleft.X + ((bottomright.X - bottomleft.X) / 2);
        MidBottom.Y = bottomleft.Y;
        Center.X = MidTop.X;
        Center.Y = MidLeft.Y;
        //collect the existing data from the corners of the area passed to algo
        float TopLeftDat, TopRightDat, BottomLeftDat, BottomRightDat;
        TopLeftDat = GetTerrainData(topleft.X, topleft.Y);          
        TopRightDat = GetTerrainData(topright.X, topright.Y);          
        BottomLeftDat = GetTerrainData(bottomleft.X, bottomleft.Y);          
        BottomRightDat = GetTerrainData(bottomright.X, bottomright.Y);
        //and the center

        //adverage data and insert for midpoints..
        SetTerrainData(MidLeft.X, MidLeft.Y, CalculateTerrainPointData(TopLeftDat, BottomLeftDat, MidLeft.X, MidLeft.Y));
        SetTerrainData(MidRight.X, MidRight.Y, CalculateTerrainPointData(TopRightDat, BottomRightDat, MidRight.X, MidRight.Y));
        SetTerrainData(MidTop.X, MidTop.Y, CalculateTerrainPointData(TopLeftDat, TopRightDat, MidTop.X, MidTop.Y));
        SetTerrainData(MidBottom.X, MidBottom.Y, CalculateTerrainPointData(BottomLeftDat, BottomRightDat, MidBottom.X, MidBottom.Y));
        SetTerrainData(Center.X, Center.Y, CalculateTerrainPointData2(TopLeftDat, TopRightDat, BottomLeftDat, BottomRightDat, Center.X, Center.Y));

        debug_displacement_iterations++;
        //and recursively fire off new calls to the function to do the smaller squares
        Rectangle NewTopLeft = new Rectangle(topleft.X, topleft.Y, Center.X - topleft.X, Center.Y - topleft.Y);
        Rectangle NewTopRight = new Rectangle(Center.X, topright.Y, topright.X - Center.X, Center.Y - topright.Y);
        Rectangle NewBottomLeft = new Rectangle(bottomleft.X, Center.Y, Center.X - bottomleft.X, bottomleft.Y - Center.Y);
        Rectangle NewBottomRight = new Rectangle(Center.X , Center.Y, bottomright.X - Center.X, bottomright.Y - Center.Y);
        MidPointDisplace(new Vector2_I(NewTopLeft.Left, NewTopLeft.Top), new Vector2_I(NewTopLeft.Right, NewTopLeft.Top), new Vector2_I(NewTopLeft.Left, NewTopLeft.Bottom), new Vector2_I(NewTopLeft.Right, NewTopLeft.Bottom));
        MidPointDisplace(new Vector2_I(NewTopRight.Left, NewTopRight.Top), new Vector2_I(NewTopRight.Right, NewTopRight.Top), new Vector2_I(NewTopRight.Left, NewTopRight.Bottom), new Vector2_I(NewTopRight.Right, NewTopRight.Bottom));
        MidPointDisplace(new Vector2_I(NewBottomLeft.Left, NewBottomLeft.Top), new Vector2_I(NewBottomLeft.Right, NewBottomLeft.Top), new Vector2_I(NewBottomLeft.Left, NewBottomLeft.Bottom), new Vector2_I(NewBottomLeft.Right, NewBottomLeft.Bottom));
        MidPointDisplace(new Vector2_I(NewBottomRight.Left, NewBottomRight.Top), new Vector2_I(NewBottomRight.Right, NewBottomRight.Top), new Vector2_I(NewBottomRight.Left, NewBottomRight.Bottom), new Vector2_I(NewBottomRight.Right, NewBottomRight.Bottom));
    }
    //helper function to return a data value adveraged from two inputs, noise value added for randomness and result clamped to ensure a good value
    private float CalculateTerrainPointData(float DataA, float DataB, int NoiseX, int NoiseY)
    {
         return MathHelper.Clamp(((DataA + DataB) / 2.0f) + NoiseFunction(NoiseX, NoiseY), 0.0f, 1.0f) * 1.0f;
    }
    //helper function to return a data value adveraged from four inputs, noise value added for randomness and result clamped to ensure a good value
    private float CalculateTerrainPointData2(float DataA, float DataB, float DataC, float DataD, int NoiseX, int NoiseY)
    {
        return MathHelper.Clamp(((DataA + DataB + DataC + DataD) / 4.0f) + NoiseFunction(NoiseX, NoiseY), 0.0f, 1.0f) * 1.5f;
    }
    private float NoiseFunction(int x, int y)
    {
        return (float)(RandomGenerator.NextDouble() - 0.5) * 0.5f;
    }

好的，谢谢你花时间看——希望有人知道这个网格状的图案是从哪里出现的：）

*edit-意外写入int，更正为浮动