我正在编写一个简单的类来解析OBJ并在之后呈现obj。我已经编写了一种从RAM中绘制顶点数组的方法，我想稍微优化它（我读到使用VBO可以获得x4倍的帧速率！）。
可悲的是，我失败了，我跟着一堆教程无济于事。 这是解析器以及在GPU上存储顶点和索引缓冲区的调用，我很好地调试了解析器本身，这没关系。 vertexBuffer和vertexIndices都被正确加载（我打印它们并根据obj文件手动检查它们。）Mesh::Mesh(string path) {
float* normals;
float* faces;
float* textures;
string fullpath = path + ".obj";
this->mats = loadMtl(path); //Loads a Material list, not used now drawing white
string line;
ifstream objFile(fullpath.c_str());
if (objFile.is_open()) {
objFile.seekg(0, ios::end);
long fileSize = long(objFile.tellg());
objFile.seekg(0, ios::beg);
// Init buffers and indices
unsigned int inserted = 0;
string currentMtl = "";
float* vertexBuffer = new float[fileSize];
float* textureBuffer = new float[fileSize];
float* normalBuffer = new float[fileSize];
unsigned int* vertexIndices = new unsigned int[fileSize];
unsigned int* normalIndices = new unsigned int[fileSize];
unsigned int* textureIndices = new unsigned int[fileSize];
int connectedVert = 0;
int textureCoords = 0;
int normalsCount = 0;
int vertexIndex = 0;
string prefix = "usemtl";
while (!objFile.eof()) {
getline(objFile, line);
if (line.c_str()[0] == 'v' && line.c_str()[1] == ' ') {
line[0] = ' ';
sscanf_s(line.c_str(), "%f %f %f ",
&vertexBuffer[connectedVert],
&vertexBuffer[connectedVert + 1],
&vertexBuffer[connectedVert + 2]);
connectedVert += 3;
}
else if (line.c_str()[0] == 'v' && line.c_str()[1] == 't') {
line[0] = ' ';
line[1] = ' ';
sscanf_s(line.c_str(), "%f %f ",
&textureBuffer[textureCoords],
&textureBuffer[textureCoords + 1]);
textureCoords += 2;
}
else if (line.c_str()[0] == 'v' && line.c_str()[1] == 'n') {
line[0] = ' ';
line[1] = ' ';
sscanf_s(line.c_str(), "%f %f %f ",
&normalBuffer[normalsCount],
&normalBuffer[normalsCount + 1],
&normalBuffer[normalsCount + 2]);
normalsCount += 3;
}
else if (line.c_str()[0] == 'f') {
line[0] = ' ';
if (textureCoords > 0) {
sscanf_s(line.c_str(), "%i/%i/%i %i/%i/%i %i/%i/%i",
&vertexIndices[vertexIndex], &textureIndices[vertexIndex], &normalIndices[vertexIndex],
&vertexIndices[vertexIndex + 1], &textureIndices[vertexIndex +1], &normalIndices[vertexIndex +1],
&vertexIndices[vertexIndex + 2], &textureIndices[vertexIndex +2], &normalIndices[vertexIndex +2]);
}
else {
sscanf_s(line.c_str(), "%i//%i %i//%i %i//%i",
&vertexIndices[vertexIndex], &normalIndices[vertexIndex],
&vertexIndices[vertexIndex+1], &normalIndices[vertexIndex +1],
&vertexIndices[vertexIndex+2], &normalIndices[vertexIndex +2]);
}
for (int j = 0; j < 3; j++) {
vertexIndices[vertexIndex+j] -= 1;
normalIndices[vertexIndex +j] -= 1;
textureIndices[vertexIndex +j] -= 1;
}
vertexIndex += 3;
}
else if (!strncmp(line.c_str(), prefix.c_str(), strlen(prefix.c_str()))) {
inserted++;
// No more vertices, normals or texture coords to load, gen arrays on GPU
if (currentMtl == "") {
//Copy vertices to GPU
glGenBuffers(1, &this->verticesID);
glBindBuffer(GL_ARRAY_BUFFER, this->verticesID);
glBufferData(GL_ARRAY_BUFFER, sizeof(float) * connectedVert, vertexBuffer, GL_STATIC_DRAW);
/*
//Won't be bothered with normals or textures right now...
//Copy normals to GPU
glGenBuffers(1, &this->normalsID);
glBindBuffer(GL_ARRAY_BUFFER, this->normalsID);
glBufferData(GL_ARRAY_BUFFER, sizeof(float) * normalsCount, &normalBuffer[0], GL_STATIC_DRAW);
//Copy UV to GPU
if (textureCoords > 0) {
glGenBuffers(1, &this->textID);
glBindBuffer(GL_ARRAY_BUFFER, this->textID);
glBufferData(GL_ARRAY_BUFFER, sizeof(float) * textureCoords, &textureBuffer[0], GL_STATIC_DRAW);
}*/
}
else {
// Filled up an index array, copy it.
this->indices.push_back(0);
this->faces.push_back(vertexIndex);
glGenBuffers(1, &this->indices[this->indices.size() - 1]);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, this->indices[this->indices.size() - 1]);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * vertexIndex, vertexIndices, GL_STATIC_DRAW);
}
currentMtl = line.substr(7, line.length());
vertexIndex = 0;
}
}
// Copy the last indices buffer.
if (currentMtl != "" && indices.size() < inserted) {
this->indices.push_back(0);
this->faces.push_back(vertexIndex);
glGenBuffers(1, &this->indices[this->indices.size() - 1]);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, this->indices[this->indices.size() - 1]);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * vertexIndex, vertexIndices, GL_STATIC_DRAW);
}
objFile.close();
delete[] vertexBuffer;
delete[] textureBuffer;
delete[] normalBuffer;
delete[] vertexIndices;
delete[] normalIndices;
delete[] textureIndices;
}
else {
throw runtime_error("Unable to load obj file: " + path + ".obj");
}
}
最后，这是抽奖电话。我猜这个问题在这里，但我不能完全理解这个问题。我已经使用glIntercept来查看是否有什么东西搞砸了但我没有错误。
void Mesh::draw() {
//Binding Vertex array
glBindBuffer(GL_ARRAY_BUFFER, this->verticesID);
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, (void*)0);
for (unsigned int i = 0; i < this->indices.size(); i++) {
glColor3f(1.0f, 1.0f, 1.0f); // Draw it in plain ol' white
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, this->indices[i]);
glDrawElements(GL_TRIANGLES,this->faces[i], GL_UNSIGNED_INT,(void*)0);
}
glDisableClientState(GL_VERTEX_ARRAY);
}
如果需要，这是Mesh类声明：
class Mesh {
public:
GLuint verticesID, textID, normalsID;
vector<GLuint> indices;
vector<GLuint> faces;
vector<Material> mats;
public:
Mesh(string path);
void draw();
~Mesh();
};
将OpenGL主要版本设置为2，将辅助设置为1.正如我之前提到的，我认为OpenGL设置正确，因为我能够在直接模式下绘制三角形并使用RAM中的顶点指针。欢迎任何帮助：）
答案 0 :(得分：3)
读取文件Mesh的构造函数，并生成对象缓冲区（glGenBuffers）。在析构函数Mesh::~Mesh中，对象缓冲区被销毁（glDeleteBuffers）。
但您push_back Mesh到std::vector。这意味着生成临时Mesh对象，该对象读取文件并在其构造函数中生成对象缓冲区。此时，所有数据都有效，并生成对象缓冲区（GPU）。在致电std::vector::push_back时，会在Mesh中生成新的std::vector对象。该对象由默认的复制构造函数构造，并获取第一个Mesh对象的所有成员的副本。完成此操作后，临时Mesh对象将立即被销毁，对象缓冲区将被临时对象的析构函数glDeleteBuffers删除（Mesh::~Mesh）。此时所有数据都消失了。
见std::vector::push_back。在破坏者Mesh::~Mesh中放置断点，然后您可以简单地跟踪到期日。
您不应该在类的构造函数和析构函数中生成和删除GPU对象，除非您使类不可复制且不复制可构造：< / p>
class Mesh
{
Mesh(const Mesh &) = delete;
Mesh & operator = (const Mesh &) = delete;
....
};
您可以通过替换
快速修复此行为，以解决调试问题test.meshes.push_back(Mesh("tri"));
通过
test.meshes.emplace_back("tri");
但最后你应该做点什么：
vector<std::unique_ptr<Mesh>> meshes;
meshes.emplace_back(new Mesh("tri"));