loadOBJ.cpp

#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <glm/glm.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <iostream>
#include <limits>
#include <string>
#include "loadOBJ.h"

bool loadOBJ(const char * path,
             std::vector < float > & out_vertices,
             std::vector < float > & out_uvs,
             std::vector < float > & out_normals,
             int &vertexCount
            ) {
    vertexCount = 0;
        std::vector < unsigned int > vertexIndices, uvIndices, normalIndices;
    std::vector < float > temp_vertices;
    std::vector < float > temp_uvs;
    std::vector < float > temp_normals;
    float minX=FLT_MAX;
    float maxX=FLT_MIN;
    float minZ=FLT_MAX;
    float maxZ=FLT_MIN;
    FILE * file = fopen(path, "r");
    if(file == NULL) {
        fprintf(stderr,"Can't read file!!! %s\n",path);
        return false;
    }
    while(1) {
        char lineHeader[512];
        int res = fscanf(file, "%s", lineHeader);
        if(res == EOF)
            break;
        if(strcmp(lineHeader, "v") == 0) {
            float x;
            float y;
            float z;
            fscanf(file, "%f %f %f\n", &x, &y, &z);
            temp_vertices.push_back(x);
            temp_vertices.push_back(-z);
            temp_vertices.push_back(y);
            if(x<minX) minX=x;
            if(x>maxX) maxX=x;
            if(y<minZ) minZ=y;
            if(y>maxZ) maxZ=y;
        } else if(strcmp(lineHeader, "vt") == 0) {
            float uvx;
            float uvy;
            fscanf(file, "%f %f\n", &uvx, &uvy);
            temp_uvs.push_back(uvx);
            temp_uvs.push_back(1-uvy);
        } else if(strcmp(lineHeader, "vn") == 0) {
            float nx;
            float ny;
            float nz;
            fscanf(file, "%f %f %f\n", &nx, &ny, &nz);
            temp_normals.push_back(nx);
            temp_normals.push_back(-nz);
            temp_normals.push_back(ny);
        } 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) {
                fprintf(stderr,"Wrong file format! Try with another options! \n");
                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]);
        }
    }

    float temp_vect_normals[temp_vertices.size()];
    for(unsigned int i=0; i<temp_vertices.size(); i++) {
        temp_vect_normals[i]=0.0f;
    }
    vertexCount = vertexIndices.size();
    for(unsigned int i=0; i<vertexIndices.size(); i++) {
        unsigned int vertexIndex = 3*(vertexIndices[i]-1);
        float vertex = temp_vertices[ vertexIndex ];
        out_vertices.push_back(vertex);
        vertex = temp_vertices[ vertexIndex+1];
        out_vertices.push_back(vertex);
        vertex = temp_vertices[ vertexIndex+2 ];
        out_vertices.push_back(vertex);
        out_vertices.push_back(1.0f);
        unsigned int normalIndex = 3*(normalIndices[i]-1);
        temp_vect_normals[vertexIndex] += temp_normals[ normalIndex ];
        temp_vect_normals[vertexIndex+1] += temp_normals[ normalIndex +1];
        temp_vect_normals[vertexIndex+2] += temp_normals[ normalIndex +2];
    }
    for(unsigned int i=0; i<temp_vertices.size();) {
        glm::vec3 temp = glm::vec3(temp_vect_normals[i],
                                   temp_vect_normals[i+1],
                                   temp_vect_normals[i+2]);
        glm::vec3 temp2 = glm::normalize(temp);
        temp_vect_normals[i]=temp2.x;
        temp_vect_normals[i+1]=temp2.y;
        temp_vect_normals[i+2]=temp2.z;
        i+=3;
    }
    for(unsigned int i=0; i<vertexIndices.size(); i++) {
        unsigned int vertexIndex = 3*(vertexIndices[i]-1);
        float normal = temp_vect_normals[ vertexIndex ];
        out_normals.push_back(normal);
        normal = temp_vect_normals[ vertexIndex+1 ];
        out_normals.push_back(normal);
        normal = temp_vect_normals[ vertexIndex+2 ];
        out_normals.push_back(normal);
        out_normals.push_back(0.0f);
    }
    for(unsigned int i=0; i<uvIndices.size(); i++) {
        unsigned int uvIndex = 2*(uvIndices[i]-1);
        float uv = temp_uvs[ uvIndex ];
        out_uvs.push_back(uv);
        uv = temp_uvs[ uvIndex+1 ];
        out_uvs.push_back(uv);
    }
    return true;
}