model.cpp

#include "model.h"
#include <sstream>
#include <fstream>
#include <iostream>
Model::Model(const std::string filename)
{
    std::ifstream in;
    in.open(filename, std::ifstream::in);
    if (in.fail()) return;
    std::string line;
    while (!in.eof()) {
        std::getline(in, line);
        std::istringstream iss(line.c_str());
        char trash;
        if (line.compare(0, 2, "v ") == 0) {
            iss >> trash;
            vec3 v;
            for (int i = 0; i < 3; i++)
            {
	            iss >> v[i];
            }
            verts.push_back(v);
        }
        else if (line.compare(0, 3, "vn ") == 0) {
            iss >> trash >> trash;
            vec3 n;
            for (int i = 0; i < 3; i++)
            {
	            iss >> n[i];
            }
            norms.push_back(n.normalize());
        }
        else if (line.compare(0, 3, "vt ") == 0) {
            iss >> trash >> trash;
            vec2 uv;
            for (int i = 0; i < 2; i++)
            {
	            iss >> uv[i];
            }
            tex_coord.emplace_back(uv.x, 1 - uv.y);
        }
        else if (line.compare(0, 2, "f ") == 0) {
            int f, t, n;
            iss >> trash;
            int cnt = 0;
            while (iss >> f >> trash >> t >> trash >> n) {
                facet_vrt.push_back(--f);
                facet_tex.push_back(--t);
                facet_nrm.push_back(--n);
                cnt++;
            }
            if (3 != cnt) {
                std::cerr << "Error: the obj file is supposed to be triangulated" << std::endl;
                in.close();
                return;
            }
        }
    }
    in.close();
     std::cerr << "# v# " << nverts() << " f# " << nfaces() << " vt# " << tex_coord.size() << " vn# " << norms.size() << std::endl;
    load_texture(filename, "_diffuse.tga", diffusemap);
    load_texture(filename, "_nm.tga", normalmap);
    load_texture(filename, "_nm_tangent.tga", normal_tangent_map);
    load_texture(filename, "_spec.tga", specularmap);
}
int Model::nverts() const {
    return verts.size();
}

int Model::nfaces() const {
    return facet_vrt.size() / 3;
}

vec3 Model::vert(const int i) const {
    return verts[i];
}

vec3 Model::vert(const int iface, const int nthvert) const {
    return verts[facet_vrt[iface * 3 + nthvert]];
}

void Model::load_texture(std::string filename, const std::string suffix, TGAImage& img) {
    size_t dot = filename.find_last_of(".");
    if (dot == std::string::npos) return;
    std::string texfile = filename.substr(0, dot) + suffix;
    std::cerr << "texture file " << texfile << " loading " << (img.read_tga_file(texfile.c_str()) ? "ok" : "failed") << std::endl;
}

vec2 Model::uv(const int iface, const int nthvert) const {
    return tex_coord[facet_tex[iface * 3 + nthvert]];
}

vec3 Model::normal(const int iface, const int nthvert) const
{
    return norms[facet_nrm[iface * 3 + nthvert]];
}

vec3 Model::normal(const vec2& uvf) const {
    TGAColor c = normalmap.get(uvf[0] * normalmap.width(), uvf[1] * normalmap.height());
    return vec3{ (double)c[2],(double)c[1],(double)c[0] }*2. / 255. - vec3{ 1,1,1 };
}

vec3 Model::normal_tangent(const vec2& uvf) const
{
    TGAColor c = normal_tangent_map.get(uvf[0] * normal_tangent_map.width(), uvf[1] * normal_tangent_map.height());
    return vec3{ (double)c[2],(double)c[1],(double)c[0] }*2. / 255. - vec3{ 1,1,1 };
}

const TGAColor& Model::diffuse(double u, double v)
{
    auto& diff = diffusemap;
    auto diffU = diff.width() * u;
    auto diffY = diff.height() * v;
    auto diffColor = diff.get(diffU, diffY);
    return diffColor;
}

const TGAColor& Model::spec(double u, double v)
{
    auto& diff = specularmap;
    auto diffU = diff.width() * u;
    auto diffY = diff.height() * v;
    auto diffColor = diff.get(diffU, diffY);
    return diffColor;
}