如何計算正常三角形帶

我有我的OPENGL項目的照明問題。我使用ECLIPSE在C++上編程。我有一個由三角形帶構建的terrein。我的渲染代碼是如下：如何計算正常三角形帶

HeightMap::~HeightMap(void) { 
} 

float HeightMap::getScaledGrayColor(double height) { 
float fColor = NULL; 
if (height == this->NODATA_value) { 
    return 0.0f; 
} 
fColor = ((255.00f/max) * height)/255.00f; 

return fColor; 
} 
double* HeightMap::getHeights(int rowNumber) { 
rowNumber = rowNumber + 6; 

ifstream fin(this->filename); 
string s; 
long length; 

fin.seekg(0, ios::beg); // go to the first line 

for (int i = 0; i < rowNumber; i++) { // loop 'till the desired line 
    getline(fin, s); 
} 

string nextToken; 
getline(fin, nextToken); 
StringUtils stringUtils; 
vector<string> tempVec = stringUtils.split(nextToken, " "); 
double* heights = new double[this->ncols]; 
for (int i = 0; i < tempVec.size() - 1; i++) { 
    heights[i] = strtod(tempVec[i].c_str(), NULL); 
} 
return heights; 
} 


void HeightMap::Render(void) 
{ 
int x = 0; 
int i = 0; 
for (int i = 0, j = 0; j < nrows; i--, j++) { 
    //cout<<"valore di i è: "<<i<<endl; 
    //cout<<"valore di j è: "<<j<<endl; 
    double * rowHeights = this->getHeights(j);// 
    for (int x = 0; x < ncols; x++) { 

     float color = getScaledGrayColor(rowHeights[x]); 
     double * Quote = this->getHeights(x); 
     glBegin(GL_TRIANGLE_STRIP); 
     glColor3f(color, color, color); 

     //triangolo ABC 
     //glNormal3f((x * cellsize), (i * cellsize), 0); 
     glVertex3f((x * cellsize), (i * cellsize), 0); //vertice base 
     //glNormal3f((x * cellsize), ((i * cellsize) + cellsize), 0); 
     glVertex3f((x * cellsize), ((i * cellsize) + cellsize), 
0);//vertice base 
     //glNormal3f(((x * cellsize) + (cellsize/2)), ((i * cellsize)+ 
(cellsize/2)), *Quote);//vertice altezza 
     glVertex3f(((x * cellsize) + (cellsize/2)), ((i * cellsize) 
       + (cellsize/2)), *Quote);//vertice altezza 


     //triangolo DEF 
     //glNormal3f((x * cellsize), (i * cellsize) + cellsize, 0); 
     glVertex3f((x * cellsize), (i * cellsize) + cellsize, 0); 
//vertice base 
     //glNormal3f((x * cellsize) + cellsize, (i * cellsize) + cellsize, 
0);//vertice base 
     glVertex3f((x * cellsize) + cellsize, (i * cellsize) + cellsize, 
0);//vertice base 
     //glNormal3f(((x * cellsize) + (cellsize/2)), ((i * cellsize)+ 
(cellsize/2)), *Quote);//vertice altezza 
     glVertex3f(((x * cellsize) + (cellsize/2)), ((i * cellsize) 
          + (cellsize/2)), 
*Quote);//vertice altezza 

     //triangolo GHI 
     //glNormal3f((x * cellsize) + cellsize, (i * cellsize) + cellsize, 
0); //vertice base 
     glVertex3f((x * cellsize) + cellsize, (i * cellsize) + cellsize, 
0); //vertice base 
     //glNormal3f((x * cellsize) + cellsize, i * cellsize, 0);//vertice 
base 
     glVertex3f((x * cellsize) + cellsize, i * cellsize, 0);//vertice 
base 
     //glNormal3f(((x * cellsize) + (cellsize/2)), ((i * cellsize)+ 
(cellsize/2)), *Quote);//vertice altezza 
     glVertex3f(((x * cellsize) + (cellsize/2)), ((i * cellsize) 
          + (cellsize/2)), 
*Quote);//vertice altezza 

     //triangolo LMN 
     //glNormal3f((x * cellsize), (i * cellsize), 0); //vertice base 
     glVertex3f((x * cellsize), (i * cellsize), 0); //vertice base 
     //glNormal3f((x * cellsize) + cellsize, (i * cellsize), 
0);//vertice base 
     glVertex3f((x * cellsize) + cellsize, (i * cellsize), 0);//vertice 
base 
     //glNormal3f(((x * cellsize) + (cellsize/2)), ((i * cellsize)+ 
(cellsize/2)), *Quote);//vertice altezza 
     glVertex3f(((x * cellsize) + (cellsize/2)), ((i * cellsize) 
          + (cellsize/2)), 
*Quote);//vertice altezza 
     glEnd(); 
     } 
    //} 
} 

}

我嘗試使用一個正常的頂點，但我不知道如何計算glnormal函數的參數。然後，我必須使用正常的臉。你能幫我解決這個問題嗎？

是的，我需要正常通過面和後，我必須做正常通過頂點：普通I爲此空隙高度圖::渲染（無效） { INT 通過臉部X = 0; int i = 0; glPushMatrix（）; glRotatef（angle，xrot，yrot，zrot）; //旋轉對象 cout < <「valore di nrowsè：」< getHeights（j）; float vectorba [3] = {0.0,0.0,0.0}; 浮子vectorcb [3] = {0.0,0.0,0.0}; float xnormal = 0.0; float ynormal = 0.0; float znormal = 0.0; float len = 0.0;

for (int x = 0; x < ncols; x++) { 
     //if (rowHeights[x] != this->NODATA_value) { 
     float color = getScaledGrayColor(rowHeights[x]); 
     double * Quote = this->getHeights(x); 
     glBegin(GL_TRIANGLE_STRIP); 
     glColor3f(color, color, color); 
     //triangolo ABC 

     //inizio normal 
     vectorba[0]={(x * cellsize)-(x * cellsize)}; 
     vectorba[1]={((i * cellsize) + cellsize)-(i * cellsize)}; 
     vectorcb[0]={((x * cellsize) + (cellsize/2))-(x * cellsize)}; 
     vectorcb[1]={((i * cellsize) + (cellsize/2))-((i * cellsize)  +cellsize)}; 
     vectorcb[2]=*Quote; 
     // calculate the cross product and place the resulting vector 
     // into the variable xnormal,ynormal e znormal 
     xnormal = (vectorba[1] * vectorcb[2]) - (vectorba[2] *  vectorcb[1]); 
     ynormal = (vectorba[2] * vectorcb[0]) - (vectorba[0] * vectorcb[2]); 
     znormal = (vectorba[0] * vectorcb[1]) - (vectorba[1] * vectorcb[0]); 
     //fine normal 

     //inizio normalize 
     // calculate the length of the vector 
      len = (float)(sqrt((xnormal * xnormal) + (ynormal * ynormal) + (znormal * znormal))); 

      // avoid division by 0 
      if (len == 0.0f) 
       len = 1.0f; 

      // reduce to unit size 
      xnormal /= len; 
      ynormal /= len; 
      znormal /= len; 
      //fine normalize 

     //glNormal3f((x * cellsize), (i * cellsize), 0); //normal per vertex. controllare la formula 
     glVertex3f((x * cellsize), (i * cellsize), 0); //vertice base A 
     //glNormal3f((x * cellsize), ((i * cellsize) + cellsize), 0); 
     glVertex3f((x * cellsize), ((i * cellsize) + cellsize), 0);//vertice base B 

     glNormal3f(xnormal, ynormal, znormal); //normal per face 

     //glNormal3f(((x * cellsize) + (cellsize/2)), ((i * cellsize)+ (cellsize/2)), *Quote);//vertice altezza 
     glVertex3f(((x * cellsize) + (cellsize/2)), ((i * cellsize) 
       + (cellsize/2)), *Quote);//vertice altezza C 


     //triangolo DEF 

     //inizio normal 
     vectorba[0]={(x * cellsize) + cellsize-(x * cellsize)}; 
     vectorba[1]={((i * cellsize) + cellsize)-((i * cellsize) + cellsize)}; 
     vectorcb[0]={((x * cellsize) + (cellsize/2))-(x * cellsize) + cellsize}; 
     vectorcb[1]={((i * cellsize)+ (cellsize/2))-((i * cellsize) + cellsize)}; 
     vectorcb[2]=*Quote; 
     // calculate the cross product and place the resulting vector 
     // into the variable xnormal,ynormal e znormal 
     xnormal = (vectorba[1] * vectorcb[2]) - (vectorba[2] * vectorcb[1]); 
     ynormal = (vectorba[2] * vectorcb[0]) - (vectorba[0] * vectorcb[2]); 
     znormal = (vectorba[0] * vectorcb[1]) - (vectorba[1] * vectorcb[0]); 
     //fine normal 

     //inizio normalize 
     // calculate the length of the vector 
     len = (float)(sqrt((xnormal * xnormal) + (ynormal * ynormal) + (znormal * znormal))); 

     // avoid division by 0 
     if (len == 0.0f) 
      len = 1.0f; 

     // reduce to unit size 
     xnormal /= len; 
     ynormal /= len; 
     znormal /= len; 
     //fine normalize 

     //glNormal3f((x * cellsize), (i * cellsize) + cellsize, 0); 
     glVertex3f((x * cellsize), (i * cellsize) + cellsize, 0); //vertice base D 
     //glNormal3f((x * cellsize) + cellsize, (i * cellsize) + cellsize, 0);//vertice base 
     glVertex3f((x * cellsize) + cellsize, (i * cellsize) + cellsize, 0);//vertice base E 

     glNormal3f(xnormal, ynormal, znormal); //normal per face 

     //glNormal3f(((x * cellsize) + (cellsize/2)), ((i * cellsize)+ (cellsize/2)), *Quote);//vertice altezza 
     glVertex3f(((x * cellsize) + (cellsize/2)), ((i * cellsize)+ (cellsize/2)), *Quote);//vertice altezza F 

     //triangolo GHI 

     //inizio normal 
     vectorba[0]={(x * cellsize) + cellsize-(x * cellsize) + cellsize}; 
     vectorba[1]={i * cellsize-(i * cellsize) + cellsize}; 
     vectorcb[0]={((x * cellsize) + (cellsize/2))-(x * cellsize) + cellsize}; 
     vectorcb[1]={((i * cellsize)+ (cellsize/2))-(i * cellsize)}; 
     vectorcb[2]=*Quote; 
     // calculate the cross product and place the resulting vector 
     // into the variable xnormal,ynormal e znormal 
     xnormal = (vectorba[1] * vectorcb[2]) - (vectorba[2] * vectorcb[1]); 
     ynormal = (vectorba[2] * vectorcb[0]) - (vectorba[0] * vectorcb[2]); 
     znormal = (vectorba[0] * vectorcb[1]) - (vectorba[1] * vectorcb[0]); 
     //fine normal 

     //inizio normalize 
     // calculate the length of the vector 
     len = (float)(sqrt((xnormal * xnormal) + (ynormal * ynormal) + (znormal * znormal))); 
     // avoid division by 0 
     if (len == 0.0f) 
      len = 1.0f; 

     // reduce to unit size 
     xnormal /= len; 
     ynormal /= len; 
     znormal /= len; 
     //fine normalize 

     //glNormal3f((x * cellsize) + cellsize, (i * cellsize) + cellsize, 0); //vertice base 
     glVertex3f((x * cellsize) + cellsize, (i * cellsize) + cellsize, 0); //vertice base G 
     //glNormal3f((x * cellsize) + cellsize, i * cellsize, 0);//vertice base 
     glVertex3f((x * cellsize) + cellsize, i * cellsize, 0);//vertice base H 

     glNormal3f(xnormal, ynormal, znormal); //normal per face 

     //glNormal3f(((x * cellsize) + (cellsize/2)), ((i * cellsize)+ (cellsize/2)), *Quote);//vertice altezza 
     glVertex3f(((x * cellsize) + (cellsize/2)), ((i * cellsize)+ (cellsize/2)), *Quote);//vertice altezza I 

     //triangolo LMN 

     //inizio normal 
     vectorba[0]={(x * cellsize) + cellsize-(x * cellsize)}; 
     vectorba[1]={(i * cellsize)-(i * cellsize)}; 
     vectorcb[0]={((x * cellsize) + (cellsize/2))-(x * cellsize) + cellsize}; 
     vectorcb[1]={((i * cellsize)+ (cellsize/2))-(i * cellsize)}; 
     vectorcb[2]=*Quote; 
     // calculate the cross product and place the resulting vector 
     // into the variable xnormal,ynormal e znormal 
     xnormal = (vectorba[1] * vectorcb[2]) - (vectorba[2] * vectorcb[1]); 
     ynormal = (vectorba[2] * vectorcb[0]) - (vectorba[0] * vectorcb[2]); 
     znormal = (vectorba[0] * vectorcb[1]) - (vectorba[1] * vectorcb[0]); 
     //fine normal 

     //inizio normalize 
     // calculate the length of the vector 
     len = (float)(sqrt((xnormal * xnormal) + (ynormal * ynormal) + (znormal * znormal))); 
     // avoid division by 0 
     if (len == 0.0f) 
      len = 1.0f; 
     // reduce to unit size 
     xnormal /= len; 
     ynormal /= len; 
     znormal /= len; 
     //fine normalize 

     //glNormal3f((x * cellsize), (i * cellsize), 0); //vertice base 
     glVertex3f((x * cellsize), (i * cellsize), 0); //vertice base L 
     //glNormal3f((x * cellsize) + cellsize, (i * cellsize), 0);//vertice base 
     glVertex3f((x * cellsize) + cellsize, (i * cellsize), 0);//vertice base M 

     glNormal3f(xnormal, ynormal, znormal); //normal per face 

     //glNormal3f(((x * cellsize) + (cellsize/2)), ((i * cellsize)+ (cellsize/2)), *Quote);//vertice altezza 
     glVertex3f(((x * cellsize) + (cellsize/2)), ((i * cellsize)+  (cellsize/2)), *Quote);//vertice altezza N 
     glEnd(); 
     } 
    //} 
} 
glPopMatrix(); 
}

該公式是正確的？我如何改變使用功能正常的渲染和規範？

來源

2012-08-27 Agata

如果我的理解，你想面對正常嗎？

如果有三角點，你可以計算出正常的每個面。

在此請看：

http://www.opengl.org/wiki/Calculating_a_Surface_Normal

正常的頂點可能採取面之間的平均法線來計算。

來源

2012-08-27 15:09:44 felipe

是的，我需要面對正常。在執行正常人臉後，我必須按照頂點做正常。對於正常的人臉我做下面的代碼： – Agata

如何計算正常三角形帶

回答

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