我编写了一个非常基本的 .obj 文件加载器（只加载顶点坐标和三角形面索引）和渲染器。当我一次只加载一个模型时，效果很好。当我加载第二个模型（或更多）时，每个模型都会绘制自己和其他模型的一部分，我绞尽脑汁想弄清楚为什么会这样。
一些相关的代码片段：
这是我打开 .obj 文件并从文件中读取顶点坐标和三角形面索引的地方。
bool Model::loadFromFile(string fileName)
{
vector<GLfloat> vertices;
vector<GLuint> indices;
fstream file(fileName);
string line = "";
while (getline(file, line))
{
istringstream lineReader(line);
char c;
//read the first letter of the line
//The first letter designates the meaning of the rest of the line
lineReader >> c;
vec3 vertex; //if we need to read .x, .y, and .z from the file
GLuint index[3]; //if we need to read the 3 indices on a triangle
switch (c)
{
case '#':
//we do nothing with comment lines
break;
case 'v': //V means vertex coords
case 'V': //so Load it into a vec3
lineReader >> vertex.x >> vertex.y >> vertex.z;
vertices.push_back(vertex.x);
vertices.push_back(vertex.y);
vertices.push_back(vertex.z);
break;
case 'vt':
case 'VT':
//no tex coords yet either
break;
case 'f': //F means indices of a face
case 'F':
lineReader >> index[0] >> index[1] >> index[2];
//we subtract one from each index in the file because
//openGL indices are 0-based, but .obj has them as
//1-based
indices.push_back(index[0] - 1);
indices.push_back(index[1] - 1);
indices.push_back(index[2] - 1);
cout << "Indices: " << index[0] << ", " << index[1] << ", " << index[2] << endl;
break;
}
}
return this->load(vertices, indices);
}
在 loadFromFile 方法结束时，我们将索引和顶点向量传递给 model::load() 方法，该方法创建并绑定 VAO、VBO 和 IBO。
bool Model::load(vector<float>& vertices, vector<GLuint>& indices)
{
//create the VAO
glGenVertexArrays(1, &handle);
glBindVertexArray(getHandle());
//and enable vertexPositionAttribute
glEnableVertexAttribArray(pShader->getPositionAttribIndex());
//Populate the position portion of the
//VAO
GLuint vboID = 0;
glGenBuffers(1, &vboID);
glBindBuffer(GL_ARRAY_BUFFER, vboID);
glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat) * vertices.size(), &vertices[0], GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, vboID);
glVertexAttribPointer(pShader->getPositionAttribIndex(), 3, GL_FLOAT, GL_FALSE, 0, nullptr);
//Populate the indices portion of the
//VAO
GLuint iboID = 0;
glGenBuffers(1, &iboID);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, iboID);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(GLuint) * indices.size(), &indices[0], GL_STATIC_DRAW);
//bind nothing to avoid any mistakes or loading
//of random data to my VAO
glBindVertexArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
this->numVertices = vertices.size() / 3;
this->numIndices = indices.size();
cout << "Num Indices: " << numIndices << endl;
return true;
}
加载模型后，它的 VAO id 将存储在类变量中。VAO 在 model::bind() 方法中加载。
void Model::bind()
{
glBindVertexArray(getHandle());
}
并通过调用 glDrawElements() 进行绘制
void Model::draw()
{
//and draw me, bitchez!
glDrawElements(GL_TRIANGLES, this->numIndices, GL_UNSIGNED_INT, nullptr);
}
模型在 level::draw() 方法中绘制：
void Level::draw()
{
pShader->setViewMatrix(camera.getViewMatrix());
for (int modelIndex = 0; modelIndex < models.size(); modelIndex++)
{
models[modelIndex]->bind();
for (int drawableIndex = 0; drawableIndex < drawables.size(); drawableIndex++)
drawables[drawableIndex]->draw();
}
}
没有 OpenGL 错误，当我将其打印到控制台时，文件解析会生成正确的值。
如果有人能指出发生这种情况的方式/原因，我将不胜感激。