Question

我通过修改在线找到的一些代码创建了一个.obj加载器，解析为.obj文件我做了以下

int mesh::getMesh(char* inputFile, std::vector<std::vector<glm::vec3>> & out_vertices,std::vector < glm::vec2 > & out_uvs,std::vector < glm::vec3 > & out_normals){
    std::cout << "Attempting to load file as model " << inputFile << "\n";

    std::vector<std::vector<unsigned int>> vertexIndices, uvIndices, normalIndices;
    std::vector<glm::vec3> temp_vertices;
    std::vector<glm::vec2> temp_uvs;
    std::vector<glm::vec3> temp_normals;

    FILE * file = fopen(inputFile, "r");
    if( file == NULL ){
        std::cout << "Impossible to open the file !\n";
        return 0;
    }
    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.

         if ( strcmp( lineHeader, "v" ) == 0 ){
            glm::vec3 vertex;
            fscanf(file, "%f %f %f\n", &vertex.x, &vertex.y, &vertex.z );
            temp_vertices.push_back(vertex);
        }else if ( strcmp( lineHeader, "vt" ) == 0 ){
            glm::vec2 uv;
            fscanf(file, "%f %f\n", &uv.x, &uv.y );
            temp_uvs.push_back(uv);
        }else if ( strcmp( lineHeader, "vn" ) == 0 ){
            glm::vec3 normal;
            fscanf(file, "%f %f %f\n", &normal.x, &normal.y, &normal.z );
            temp_normals.push_back(normal);
        }else if ( strcmp( lineHeader, "f" ) == 0 ){
            unsigned int vertexIndex[3], uvIndex[3], normalIndex[3];
            int matches = fscanf(file, "%d/%d/%d %d/%d/%d %d/%d/%d\n", &vertexIndex[0], &uvIndex[0], &normalIndex[0], &vertexIndex[1], &uvIndex[1], &normalIndex[1], &vertexIndex[2], &uvIndex[2], &normalIndex[2] );
            if (matches != 9){
                std::cout << "File can't be read by the parser : ( Try exporting with other options )\n";
                return 0;
            }

            std::vector<unsigned int> vertexTriangle;
            vertexTriangle.push_back(vertexIndex[0]);
            vertexTriangle.push_back(vertexIndex[1]);
            vertexTriangle.push_back(vertexIndex[2]);
            vertexIndices.push_back(vertexTriangle);

            //uvIndices    .push_back(uvIndex[0]);
            //uvIndices    .push_back(uvIndex[1]);
            //uvIndices    .push_back(uvIndex[2]);

            //std::vector<unsigned int> normalTriangle;
            //normalTriangle.push_back(normalIndex[0]);
            //normalTriangle.push_back(normalIndex[1]);
            //normalTriangle.push_back(normalIndex[2]);
            //normalIndices.push_back(normalTriangle);
        }
    }
    for( unsigned int i=0; i<vertexIndices.size(); i++ ){
        std::vector<unsigned int> vertexIndexs=vertexIndices[i];

        //glm::vec3 vertex0 = temp_vertices[ vertexIndexs[3]-1 ];
        glm::vec3 vertex1 = temp_vertices[ vertexIndexs[0]-1 ];
        glm::vec3 vertex2 = temp_vertices[ vertexIndexs[1]-1 ];
        glm::vec3 vertex3 = temp_vertices[ vertexIndexs[2]-1 ];
        std::vector<glm::vec3> vertex;
        vertex.push_back(vertex1); vertex.push_back(vertex2); vertex.push_back(vertex3);
        out_vertices.push_back(vertex);

    }
    return 1;
}

然后我使用

绘制它

<initialization...>

std::vector<std::vector<glm::vec3>> vertices;
std::vector<glm::vec2> uvs;
std::vector<glm::vec3> normals;

mesh::getMesh("Resources/Models/cube.obj",vertices,uvs,normals);

<window handling and whatnot...>

for (unsigned i=0; i < vertices.size(); i++) {
    std::vector<glm::vec3> vertexGroup = vertices[i];
    glBegin(GL_TRIANGLES);
        glVertex3f(vertexGroup[0].x,vertexGroup[0].y,vertexGroup[0].z);
        glVertex3f(vertexGroup[1].x,vertexGroup[1].y,vertexGroup[1].z);
        glVertex3f(vertexGroup[2].x,vertexGroup[2].y,vertexGroup[2].z);
    glEnd();
}

这适用于此.obj文件

# Blender3D v249 OBJ File: untitled.blend
# www.blender3d.org
mtllib cube.mtl
v 1.000000 -1.000000 -1.000000
v 1.000000 -1.000000 1.000000
v -1.000000 -1.000000 1.000000
v -1.000000 -1.000000 -1.000000
v 1.000000 1.000000 -1.000000
v 0.999999 1.000000 1.000001
v -1.000000 1.000000 1.000000
v -1.000000 1.000000 -1.000000
vt 0.748573 0.750412
vt 0.749279 0.501284
vt 0.999110 0.501077
vt 0.999455 0.750380
vt 0.250471 0.500702
vt 0.249682 0.749677
vt 0.001085 0.750380
vt 0.001517 0.499994
vt 0.499422 0.500239
vt 0.500149 0.750166
vt 0.748355 0.998230
vt 0.500193 0.998728
vt 0.498993 0.250415
vt 0.748953 0.250920
vn 0.000000 0.000000 -1.000000
vn -1.000000 -0.000000 -0.000000
vn -0.000000 -0.000000 1.000000
vn -0.000001 0.000000 1.000000
vn 1.000000 -0.000000 0.000000
vn 1.000000 0.000000 0.000001
vn 0.000000 1.000000 -0.000000
vn -0.000000 -1.000000 0.000000
usemtl Material_ray.png
s off
f 5/1/1 1/2/1 4/3/1
f 5/1/1 4/3/1 8/4/1
f 3/5/2 7/6/2 8/7/2
f 3/5/2 8/7/2 4/8/2
f 2/9/3 6/10/3 3/5/3
f 6/10/4 7/6/4 3/5/4
f 1/2/5 5/1/5 2/9/5
f 5/1/6 6/10/6 2/9/6
f 5/1/7 8/11/7 6/10/7
f 8/11/7 7/12/7 6/10/7
f 1/2/8 2/9/8 3/13/8
f 1/2/8 3/13/8 4/14/8

但是当我进入一个更复杂的东西时，比如我从一个免费模型网站作为测试平台拍摄的一个男人的低聚模型，它缺少每个面孔的三角形（见下面的截图）

立方体： enter image description here

人形机器人 enter image description here

该男子在搅拌机中渲染得很好，所以它一定是我解析文件的方式吗？

Answer 1

您需要在将模型导出到格式时对混合器中的面进行三角测量。对于obj模型，总是在附加法线的情况下导出，并且顶点是三角形的。您可能还需要选中“保持顶点顺序”。

在OpenGL中渲染.obj文件最终会丢失顶点

1 个答案: