OpenGL使用帶有索引的VBO

Question

因此，我正在構建一個用於渲染模型和轉換的基本引擎，我使用常規VBO（無索引）完成了此工作，沒有任何問題，但是我決定改為使用具有索引的VBO。 這是我代碼的重要部分：

相關全局變量：

GLuint *modelBuffers;
GLuint *indexBuffers;

相關數據結構：

struct databaseStruct
{
    int moveSize;
    int modelSize;
    int spinSize;
    int tracerSize;

    int currentMove;
    int currentSpin;
    int currentModel;
    int currentTracer;

    vector<moveNode> moveList;
    vector<modelNode> modelList;
    vector<spinNode> spinList;
    vector<tracerNode> tracerList;
    groupStruct scene;
} database;

struct modelNode
{
    int id;
    int numTri;
    string modelName;
    vector<GLfloat> model;
    vector<GLfloat> normals;
    vector<int> indices;
};

在程序開始時進行模型初始化：

void initModels(){
    glEnableClientState(GL_VERTEX_ARRAY);
    modelBuffers = new GLuint[database.modelSize];
    indexBuffers = new GLuint[database.modelSize];
    glGenBuffers(database.modelSize, modelBuffers);
    glGenBuffers(database.modelSize, indexBuffers);
    vector<modelNode> mList = database.modelList;
    for (int i = 0; i < database.modelSize; i++){
        glBindBuffer(GL_ARRAY_BUFFER, modelBuffers[mList[i].id]);
        glBufferData(GL_ARRAY_BUFFER, mList[i].model.size()*sizeof(GLfloat), &(mList[i].model[0]), GL_STATIC_DRAW);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffers[mList[i].id]);
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, mList[i].indices.size() * sizeof(GLint), &(mList[i].indices[0]), GL_STATIC_DRAW);
    }
}

在渲染場景上進行繪制調用：

void drawModel(element* elem){
    if (elem != NULL){
        modelNode *it = &database.modelList[elem->nodeRef];
        glBindBuffer(GL_ARRAY_BUFFER, modelBuffers[it->id]);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffers[it->id]);
        glVertexPointer(3, GL_FLOAT, 0, 0);
        glDrawElements(GL_TRIANGLES, it->numTri*3, GL_INT, 0);
    }
}

程序的結構有效，因為自從使用簡單的VBO以來，我所做的所有更改都是對結構的更改，以托管索引和用於處理索引的OpenGL調用。 如果需要，我可以提供以前的工作版本。

Answer 1

您要重疊緩沖區，為頂點信息和索引創建單獨的緩沖區

void initModels(){
    glEnableClientState(GL_VERTEX_ARRAY);
    modelBuffers = new GLuint[database.modelSize*2];//twice as large
    glGenBuffers(database.modelSize*2, modelBuffers);//creating twice as many
    vector<modelNode> mList = database.modelList;
    for (int i = 0; i < database.modelSize; i++){
        glBindBuffer(GL_ARRAY_BUFFER, modelBuffers[mList[i].id*2]);
        glBufferData(GL_ARRAY_BUFFER, mList[i].model.size()*sizeof(GLfloat), &(mList[i].model[0]), GL_STATIC_DRAW);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, modelBuffers[mList[i].id*2+1]);
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, mList[i].indices.size() * sizeof(int), &(mList[i].indices[0]), GL_STATIC_DRAW);
    }
}

void drawModel(element* elem){
    if (elem != NULL){
        modelNode *it = &database.modelList[elem->nodeRef];
        glBindBuffer(GL_ARRAY_BUFFER, modelBuffers[it->id*2]);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, modelBuffers[it->id*2+1]);
        glVertexPointer(3, GL_FLOAT, 0, 0);
        glDrawElements(GL_TRIANGLES, it->numTri*3, GL_INT, 0);
    }
}

你會看到我創建的兩倍盡可能多的緩沖區，並且每個數組緩沖區是id*2在modelBuffers和索引緩沖區是id*2 + 1在modelBuffers