尝试从OpenGL中的.obj绘制网格时，某些三角形未显示

Question

我正在尝试显示从.obj文件加载的对象。 我使用此函数来读取.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init函数中调用此函数。 加载网格后，我将在此处遍历顶点显示它：

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，对象的另一端根本无法加载，并且随机三角形也丢失了。 像这样：

Answer 1

您不希望循环顶点的大小，而是循环面的大小。

您的循环应读取for (unsigned int i = 0; i < faceIndices.size(); i++)

您正在遍历变量faceIndices[i] ，我想您想绘制所有三角形，而不是所有点（顶点）！

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