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//
// Simple wavefront .obj writer
//
#include "obj_writer.h"
#include <cstdio>
static std::string GetFileBasename(const std::string& FileName)
{
if(FileName.find_last_of(".") != std::string::npos)
return FileName.substr(0, FileName.find_last_of("."));
return "";
}
bool WriteMat(const std::string& filename, const std::vector<tinyobj::material_t>& materials) {
FILE* fp = fopen(filename.c_str(), "w");
if (!fp) {
fprintf(stderr, "Failed to open file [ %s ] for write.\n", filename.c_str());
return false;
}
for (size_t i = 0; i < materials.size(); i++) {
tinyobj::material_t mat = materials[i];
fprintf(fp, "newmtl %s\n", mat.name.c_str());
fprintf(fp, "Ka %f %f %f\n", mat.ambient[0], mat.ambient[1], mat.ambient[2]);
fprintf(fp, "Kd %f %f %f\n", mat.diffuse[0], mat.diffuse[1], mat.diffuse[2]);
fprintf(fp, "Ks %f %f %f\n", mat.specular[0], mat.specular[1], mat.specular[2]);
fprintf(fp, "Kt %f %f %f\n", mat.transmittance[0], mat.specular[1], mat.specular[2]);
fprintf(fp, "Ke %f %f %f\n", mat.emission[0], mat.emission[1], mat.emission[2]);
fprintf(fp, "Ns %f\n", mat.shininess);
fprintf(fp, "Ni %f\n", mat.ior);
fprintf(fp, "illum %d\n", mat.illum);
fprintf(fp, "\n");
// @todo { texture }
}
fclose(fp);
return true;
}
bool WriteObj(const std::string& filename, const tinyobj::attrib_t& attributes, const std::vector<tinyobj::shape_t>& shapes, const std::vector<tinyobj::material_t>& materials, bool coordTransform) {
FILE* fp = fopen(filename.c_str(), "w");
if (!fp) {
fprintf(stderr, "Failed to open file [ %s ] for write.\n", filename.c_str());
return false;
}
std::string basename = GetFileBasename(filename);
std::string material_filename = basename + ".mtl";
int prev_material_id = -1;
fprintf(fp, "mtllib %s\n\n", material_filename.c_str());
// facevarying vtx
for (size_t k = 0; k < attributes.vertices.size(); k+=3) {
if (coordTransform) {
fprintf(fp, "v %f %f %f\n",
attributes.vertices[k + 0],
attributes.vertices[k + 2],
-attributes.vertices[k + 1]);
} else {
fprintf(fp, "v %f %f %f\n",
attributes.vertices[k + 0],
attributes.vertices[k + 1],
attributes.vertices[k + 2]);
}
}
fprintf(fp, "\n");
// facevarying normal
for (size_t k = 0; k < attributes.normals.size(); k += 3) {
if (coordTransform) {
fprintf(fp, "vn %f %f %f\n",
attributes.normals[k + 0],
attributes.normals[k + 2],
-attributes.normals[k + 1]);
} else {
fprintf(fp, "vn %f %f %f\n",
attributes.normals[k + 0],
attributes.normals[k + 1],
attributes.normals[k + 2]);
}
}
fprintf(fp, "\n");
// facevarying texcoord
for (size_t k = 0; k < attributes.texcoords.size(); k += 2) {
fprintf(fp, "vt %f %f\n",
attributes.texcoords[k + 0],
attributes.texcoords[k + 1]);
}
for (size_t i = 0; i < shapes.size(); i++) {
fprintf(fp, "\n");
if (shapes[i].name.empty()) {
fprintf(fp, "g Unknown\n");
} else {
fprintf(fp, "g %s\n", shapes[i].name.c_str());
}
bool has_vn = false;
bool has_vt = false;
// Assumes normals and textures are set shape-wise.
if(shapes[i].mesh.indices.size() > 0){
has_vn = shapes[i].mesh.indices[0].normal_index != -1;
has_vt = shapes[i].mesh.indices[0].texcoord_index != -1;
}
// face
int face_index = 0;
for (size_t k = 0; k < shapes[i].mesh.indices.size(); k += shapes[i].mesh.num_face_vertices[face_index++]) {
// Check Materials
int material_id = shapes[i].mesh.material_ids[face_index];
if (material_id != prev_material_id) {
std::string material_name = materials[material_id].name;
fprintf(fp, "usemtl %s\n", material_name.c_str());
prev_material_id = material_id;
}
unsigned char v_per_f = shapes[i].mesh.num_face_vertices[face_index];
// Imperformant, but if you want to have variable vertices per face, you need some kind of a dynamic loop.
fprintf(fp, "f");
for(int l = 0; l < v_per_f; l++){
const tinyobj::index_t& ref = shapes[i].mesh.indices[k + l];
if(has_vn && has_vt){
// v0/t0/vn0
fprintf(fp, " %d/%d/%d", ref.vertex_index + 1, ref.texcoord_index + 1, ref.normal_index + 1);
continue;
}
if(has_vn && !has_vt){
// v0//vn0
fprintf(fp, " %d//%d", ref.vertex_index + 1, ref.normal_index + 1);
continue;
}
if(!has_vn && has_vt){
// v0/vt0
fprintf(fp, " %d/%d", ref.vertex_index + 1, ref.texcoord_index + 1);
continue;
}
if(!has_vn && !has_vt){
// v0 v1 v2
fprintf(fp, " %d", ref.vertex_index + 1);
continue;
}
}
fprintf(fp, "\n");
}
}
fclose(fp);
//
// Write material file
//
bool ret = WriteMat(material_filename, materials);
return ret;
}
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