帮助与钻石广场算法实施

Question

我试图实现Diamond-square algorithm，但问题是只有一部分位图正在填充，我不知道有什么问题。我递归这样做：

GLuint CreateDsquare() 
    { 
     std::vector<GLubyte> pdata(256 * 256 * 4); 


     vector2i loc; 
     vector2i sz; 
     GLubyte val; 

     sz.x = 256; 
     sz.y = 256; 

     val = rand() % 255; 

     loc = vector2i(0,0); 

     pdata[loc.y * 4 * sz.x + loc.x * 4 + 0] = val; 
     pdata[loc.y * 4 * sz.x + loc.x * 4 + 1] = val; 
     pdata[loc.y * 4 * sz.x + loc.x * 4 + 2] = val; 
     pdata[loc.y * 4 * sz.x + loc.x * 4 + 3] = 255; 

     loc.x = sz.x - 1; 
     loc.y = 0; 

     val = rand() % 255; 

     pdata[loc.y * 4 * sz.x + loc.x * 4 + 0] = val; 
     pdata[loc.y * 4 * sz.x + loc.x * 4 + 1] = val; 
     pdata[loc.y * 4 * sz.x + loc.x * 4 + 2] = val; 
     pdata[loc.y * 4 * sz.x + loc.x * 4 + 3] = 255; 

     loc.x = sz.x - 1; 
     loc.y = sz.y - 1; 

     val = rand() % 255; 

     pdata[loc.y * 4 * sz.x + loc.x * 4 + 0] = val; 
     pdata[loc.y * 4 * sz.x + loc.x * 4 + 1] = val; 
     pdata[loc.y * 4 * sz.x + loc.x * 4 + 2] = val; 
     pdata[loc.y * 4 * sz.x + loc.x * 4 + 3] = 255; 

     loc.x = 0; 
     loc.y = sz.y - 1; 

     val = rand() % 255; 

     pdata[loc.y * 4 * sz.x + loc.x * 4 + 0] = val; 
     pdata[loc.y * 4 * sz.x + loc.x * 4 + 1] = val; 
     pdata[loc.y * 4 * sz.x + loc.x * 4 + 2] = val; 
     pdata[loc.y * 4 * sz.x + loc.x * 4 + 3] = 255; 

     RescursiveDiamond(pdata,sz,vector2i(0,0)); 

     return CreateTexture(pdata,256,256); 
    } 

void RescursiveDiamond(std::vector<GLubyte> &pdata,vector2i psz, vector2i offset) 
{ 
    int val; 
    int newnum; 
    if(psz.x < 2 && psz.y < 2) 
    { 
     return; 
    } 


    vector2i loc; 
    vector2i sz = psz; 

    std::vector<int> pvertz(4,0); 

    loc = offset; 
    pvertz[0] = pdata[loc.y * 4 * sz.x + loc.x * 4 + 0]; 

    loc.x = offset.x + (psz.x - 1); 
    loc.y = offset.y; 
    pvertz[1] = pdata[loc.y * 4 * sz.x + loc.x * 4 + 0]; 

    loc.x = offset.x + (psz.x - 1); 
    loc.y = offset.y + (psz.y - 1); 
    pvertz[2] = pdata[loc.y * 4 * sz.x + loc.x * 4 + 0]; 

    loc.x = offset.x; 
    loc.y = offset.y + (psz.y - 1); 
    pvertz[3] = pdata[loc.y * 4 * sz.x + loc.x * 4 + 0]; 


    val = (pvertz[0] + pvertz[1])/2; 
    val += 255; 
    loc.x = (offset.x + (sz.x - 1))/2; 
    loc.y = offset.y; 

    pdata[loc.y * 4 * sz.x + loc.x * 4 + 0] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 1] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 2] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 3] = 255; 


    val = (pvertz[1] + pvertz[2])/2; 
    val += 255; 
    loc.x = (offset.x + (sz.x)) - 1; 
    loc.y = ((offset.y + (sz.y))/2) - 1; 

    pdata[loc.y * 4 * sz.x + loc.x * 4 + 0] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 1] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 2] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 3] = 255; 


    val = (pvertz[3] + pvertz[2])/2; 
    val += 255; 
    loc.x = ((offset.x + (sz.x))/2) - 1; 
    loc.y = (offset.y + (sz.y)) - 1 ; 

    pdata[loc.y * 4 * sz.x + loc.x * 4 + 0] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 1] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 2] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 3] = 255; 


    val = (pvertz[0] + pvertz[3])/2; 
    val += 255; 
    loc.x = offset.x; 
    loc.y = (offset.y + (sz.y)) - 1 ; 

    pdata[loc.y * 4 * sz.x + loc.x * 4 + 0] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 1] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 2] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 3] = 255; 

    //center 

    val = (pdata[(offset.y) * 4 * sz.x + ((offset.x + (sz.x - 1))/2) * 4 + 0] + 
     pdata[(offset.y + (sz.y - 1)) * 4 * sz.x + ((offset.x + (sz.x - 1))/2) * 4 + 0])/2; 

    int ad = (rand() % 12) - 6; 
    if(val + ad < 0) 
    { 
     val = 0; 
    } 
    else 
    { 
     val += ad; 
    } 

    val += 255; 

    loc.x = ((offset.x + (sz.x))/2) - 1; 
    loc.y = ((offset.y + (sz.y))/2) - 1; 

    pdata[loc.y * 4 * sz.x + loc.x * 4 + 0] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 1] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 2] = val; 
    pdata[loc.y * 4 * sz.x + loc.x * 4 + 3] = 255; 



    vector2i newoffset; 
    vector2i newparentsz; 

    newoffset = offset; 
    newparentsz = (psz/2); 

    RescursiveDiamond(pdata,newparentsz,newoffset); 

    newoffset.x = offset.x + (newparentsz.x); 
    newoffset.y = offset.y; 

    RescursiveDiamond(pdata,newparentsz,newoffset); 


    newoffset.x = offset.x; 
    newoffset.y = offset.y + (newparentsz.y); 

    RescursiveDiamond(pdata,newparentsz,newoffset); 
    newoffset.x = offset.x + (newparentsz.x); 
    newoffset.y = offset.y + (newparentsz.y); 

    RescursiveDiamond(pdata,newparentsz,newoffset); 



} 

我怀疑，我可能会回想起了错误的偏移或东西的功能。

偏移就像是左上角，然后是尺寸，这些都是正方形。

这里有什么可能是错的？

感谢

Answer 1

当您计算到您的身高地图对于每行（y * pitch），您正在使用当前正在计算的平方的大小，而不是实际的256点。您进入递归的深度越深，您就会写入高度图，就好像它越来越小直到递归的最后一步写入像素（0，0）。

Answer 2

好吧，首先，让我们开始清理违规D-R-Y，你的代码应该沿着这个线路更多：

int position(_y, _x, _offset){ 
    return _y * _x * 4 + _x * 4 + _offset; 
} 

void adjust(vector<GLubyte> &pdata, _x, _y){ 
    GLubyte val = rand() % 255; 
    for(int j=0; j < 3; ++j){ 
     pdata[ position(_y, _x, j) ] = val; 
    } 
    pdata[ position(_y, _x, 3) ] = 255; 
} 

GLuint CreateDsquare(){ 
    vector2i sz; 

    sz.x = 256; 
    sz.y = 256; 

    adjust(pdata, 0, 0); 
    adjust(pdata, sz.x - 1, 0); 
    adjust(pdata, sz.x -1, sz.y - 1); 
    adjust(pdata, 0, sz.y - 1); 

    RescursiveDiamond(pdata,sz,vector2i(0,0)); 

    return CreateTexture(pdata,256,256); 
} 

可以格式化它的休息下来，它更具可读性/可理解性？然后，我会更新，以便我可以更好地回答您的问题（如果有人没有打我，或者女人决定我有足够的电脑时间）。