OpenGL -- OBJ 模型加载

使用:
// Read our .obj file
std::vector vertices;
std::vector uvs;
std::vector normals;
bool res = loadOBJ(“suzanne.obj”, vertices, uvs, normals);

实现:

#include <vector>#include <stdio.h>#include <string>#include <cstring>#include <glm/glm.hpp>#include "objloader.hpp"// Very, VERY simple OBJ loader.// Here is a short list of features a real function would provide : // - Binary files. Reading a model should be just a few memcpy's away, not parsing a file at runtime. In short : OBJ is not very great.// - Animations & bones (includes bones weights)// - Multiple UVs// - All attributes should be optional, not "forced"// - More stable. Change a line in the OBJ file and it crashes.// - More secure. Change another line and you can inject code.// - Loading from memory, stream, etcbool loadOBJ(    const char * path,     std::vector<glm::vec3> & out_vertices,     std::vector<glm::vec2> & out_uvs,    std::vector<glm::vec3> & out_normals){    printf("Loading OBJ file %s...\n", path);    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(path, "r");    if( file == NULL )    {        printf("Impossible to open the file ! Are you in the right path ? See Tutorial 1 for details\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 );            temp_vertices.push_back(vertex);        }        else if ( strcmp( lineHeader, "vt" ) == 0 )        {            glm::vec2 uv;            fscanf(file, "%f %f\n", &uv.x, &uv.y );            uv.y = -uv.y; // Invert V coordinate since we will only use DDS texture, which are inverted. Remove if you want to use TGA or BMP loaders.            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 )        {            std::string vertex1, vertex2, vertex3;            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)            {                printf("File can't be read by our simple parser :-( Try exporting with other options\n");                fclose(file);                return false;            }            vertexIndices.push_back(vertexIndex[0]);            vertexIndices.push_back(vertexIndex[1]);            vertexIndices.push_back(vertexIndex[2]);            uvIndices    .push_back(uvIndex[0]);            uvIndices    .push_back(uvIndex[1]);            uvIndices    .push_back(uvIndex[2]);            normalIndices.push_back(normalIndex[0]);            normalIndices.push_back(normalIndex[1]);            normalIndices.push_back(normalIndex[2]);        }        else        {            // Probably a comment, eat up the rest of the line            char stupidBuffer[1000];            fgets(stupidBuffer, 1000, file);        }    }    // For each vertex of each triangle    for( unsigned int i=0; i<vertexIndices.size(); i++ )    {        // Get the indices of its attributes        unsigned int vertexIndex = vertexIndices[i];        unsigned int uvIndex = uvIndices[i];        unsigned int normalIndex = normalIndices[i];        // Get the attributes thanks to the index        glm::vec3 vertex = temp_vertices[ vertexIndex-1 ];        glm::vec2 uv = temp_uvs[ uvIndex-1 ];        glm::vec3 normal = temp_normals[ normalIndex-1 ];        // Put the attributes in buffers        out_vertices.push_back(vertex);        out_uvs     .push_back(uv);        out_normals .push_back(normal);     }    fclose(file);    return true;}