c++ - 尝试从 OpenGL 中的 .object 绘制网格时不显示某些三角形

Question

我正在尝试显示从 .obj 文件加载的对象。我使用此函数读取 .obj:

bool loadOBJ(
    const char * path, 
    std::vector<glm::vec3> & vertices,
    std::vector<glm::vec3> & vertexIndices
){
    printf("Loading OBJ file %s...\n", path);

    FILE * file = fopen(path, "r");
    if( file == NULL ){
            printf("Impossible to open the file ! Are you in the right path ? \n");
            getchar();
            return false;
    }

    while( 1 ){

            char lineHeader[128];
            // read the first word of the line
            int res = fscanf(file, "%s", lineHeader);
            if (res == EOF)
                    break; // EOF = End Of File. Quit the loop.

            // else : parse lineHeader

            if ( strcmp( lineHeader, "v" ) == 0 ){
                    glm::vec3 vertex;
                    fscanf(file, "%f %f %f\n", &vertex.x, &vertex.y, &vertex.z );
                    vertices.push_back(vertex);
            }else if ( strcmp( lineHeader, "f" ) == 0 ){

                    glm::vec3 vertexIndex;
                    fscanf(file, "%f %f %f\n", &vertexIndex.x, &vertexIndex.y, &vertexIndex.z );
                    vertexIndices.push_back(vertexIndex);
            }else{
                    // Probably a comment, eat up the rest of the line
                    char stupidBuffer[1000];
                    fgets(stupidBuffer, 1000, file);
            }

    }

    return true;
}

然后我在我的初始化函数中调用这个函数。加载网格后，我通过在此处循环遍历顶点来显示它:

for (unsigned int i = 0; i < meshVertices.size(); i++)
    {
        glBegin(GL_TRIANGLES); 
            glVertex3f(meshVertices[faceIndices[i].x-1].x, meshVertices[faceIndices[i].x-1].y, meshVertices[faceIndices[i].x-1].z); 
            glVertex3f(meshVertices[faceIndices[i].y-1].x, meshVertices[faceIndices[i].y-1].y, meshVertices[faceIndices[i].y-1].z); 
            glVertex3f(meshVertices[faceIndices[i].z-1].x, meshVertices[faceIndices[i].z-1].y, meshVertices[faceIndices[i].z-1].z); 
        glEnd();

    }

但是，当程序运行时，对象的远侧根本不会加载，并且随机三角形会丢失。像这样:

Answer 1

您不想循环顶点的大小，而是循环面的大小。

你的循环应该是for (unsigned int i = 0; i < faceIndices.size(); i++)

您正在遍历变量 faceIndices[i]我想你想画所有的三角形，而不是所有的点(顶点)!

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旁注:我在教你这门类(class)吗？ :D该代码看起来很熟悉......