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该程序从织物中读取顶点和索引，并将顶点存储在向量中，将索引存储在数组中。继承人是 quad.txt -

4 2 numVertices numIndices

-1 -1 0 v1 v2 v3

1 -1 0

1 1 0

-1 1 0

1 2 3

1 3 4

然后我将对象渲染到屏幕上——没问题。但是当我尝试计算法线和平面阴影时，我遇到了问题。该对象使用 GL_TRINANGLES 进行渲染。看起来像这样http://imgur.com/wnKWP（没有足够的声誉直接上传......）

就像三角形被单独着色......无论如何这里是代码：

#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);
}
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1 回答 1

3

每个顶点需要一个法线。您当前正在计算每个三角形一个法线。看看下面关于计算法线的帖子：http: //devmaster.net/forums/topic/1065-calculating-normals-of-a-mesh/

正如文章所述，有两种方法可以计算每个顶点的法线：

  1. 顶点法线是相邻面法线的平均值（参见 devmaster 帖子中的 #1）
  2. 顶点法线是相邻面法线的角度加权平均值（参见 devmaster 帖子中的 #6）
于 2012-10-21T20:12:04.787 回答