使用glm-library計算法線OpenGL

Question

程序從紡織物讀取頂點和索引，並將頂點存儲在向量中，並將索引存儲在數組中。赫雷什是quad.txt -

4 2 numVertices numIndices

-1 -1 0 V1 V2 V3

1 -1 0

-1 1 0

然後我渲染對象到屏幕 - 沒問題。但是當我嘗試計算法線和平坦陰影時，我遇到了問題。該對象用GL_TRINANGLES呈現。它看起來像這樣http://imgur.com/wnKWP（沒有足夠的聲譽直接上傳...）

這就像三角形獲得單獨陰影...反正這裏是代碼：

#include "Object.h" 
#include <vector> 
#include <iostream> 
#include <fstream> 
#include <cstring> 
#include <glm.hpp> 


using namespace std; 

const int NMAX = 20000; 

GLuint indicesArr[NMAX]; 

vector<glm::vec3> drawFigure; glm::vec3 figure; 
vector<glm::vec3>Vertices;  glm::vec3 vertex; 
vector<glm::vec3>Normals;  glm::vec3 normal; 
vector<glm::vec3>Temp;   glm::vec3 temp; 


int numVertices, numIndices; 

//slices = number of subdivisions around the axis 
Object::Object() : 
mIsInitialised(false) 
{ 
} 

Object::~Object() 
{ 
if(mIsInitialised) 
{ 
    drawFigure.clear(); 
    Vertices.clear(); 
    Normals.clear(); 
    Temp.clear(); 
} 
} 


bool Object::loadTxtFile(const string &filename) 
{ 
ifstream in(filename); 
in >> numVertices >> numIndices; 

while (!in.eof()) 
{ 
    for (unsigned int i = 1; i <= numVertices; i++) 
    { 
     in >> vertex.x >> vertex.y >> vertex.z; 
     Vertices.push_back(vertex); 
    } 

    for (unsigned int i = 1; i <= numIndices * 3; i++) 
     in >> indicesArr[i]; 
} 

for (unsigned int i = 1; i <= (numIndices * 3); i++) 
{ 
    figure.x = Vertices[indicesArr[i] - 1].x; 
    figure.y = Vertices[indicesArr[i] - 1].y; 
    figure.z = Vertices[indicesArr[i] - 1].z; 
    drawFigure.push_back(figure); 
} 

for (unsigned int i = 0; i < (numIndices * 3); i+=3) 
{ 
    temp.x = drawFigure[i].x; 
    temp.y = drawFigure[i].y; 
    temp.z = drawFigure[i].z; 
    Temp.push_back(temp); 

    temp.x = drawFigure[i + 1].x; 
    temp.y = drawFigure[i + 1].y; 
    temp.z = drawFigure[i + 1].z; 
    Temp.push_back(temp); 

    temp.x = drawFigure[i + 2].x; 
    temp.y = drawFigure[i + 2].y; 
    temp.z = drawFigure[i + 2].z; 
    Temp.push_back(temp); 

    normal = glm::normalize(glm::cross(Temp[i + 2] - Temp[i], Temp[i + 1] - Temp[i])); 
    Normals.push_back(normal); 
} 
mIsInitialised = true; 
return true; //Return true if successfully loaded 
} 


void Object::draw() 
{ 

if(!mIsInitialised) { return; } 

//Tell OpenGL about our vertex and colour data 
glEnableClientState(GL_VERTEX_ARRAY); 
glVertexPointer(3, GL_FLOAT, 0, &drawFigure.front()); 

glEnableClientState(GL_NORMAL_ARRAY); 
glNormalPointer(GL_FLOAT, 0, &Normals.front()); 

//draw the .txt-file 
glDrawArrays(GL_TRIANGLES, 0, (numIndices * 3)); 

//restore the state GL back 
glDisableClientState(GL_VERTEX_ARRAY); 
glDisableClientState(GL_NORMAL_ARRAY); 
} 

Answer 1

你需要一個每個頂點正常。你目前的計算是每個三角形的一個正常值。看看關於計算法線以下職位：http://devmaster.net/forums/topic/1065-calculating-normals-of-a-mesh/

隨着職位描述有兩種方法來計算每個頂點的法線：

1. 頂點法線相鄰面法線的平均值（請參閱＃1中的devmaster郵政）
2. 頂點法線在相鄰的面法線（的角度加權平均看到＃6在devmaster郵政）