#include "iostream"
#include "fstream"
#include "sstream"
#include "iomanip"
#include "string.h"
#include "cmath"
#include "vector"

#define ZERO 1e-20
#define Pi (4.0*atan(1.0))

using namespace std;

struct point{
	double x,y,z;
};
typedef vector<point> pointArray;

struct spoint
{
	double lon,lat,rad;
};
typedef vector<spoint> spointArray;

struct vertex : public point{
	int id;
	double attri;
};
typedef vector<vertex> vertexArray;

struct face{
	int id;
	int vec[3] = {-1,-1,-1};
	point outNor;
};
typedef vector<face> faceArray;

point normal(point a){
	point out = a;
	double module = sqrt(a.x*a.x+a.y*a.y+a.z*a.z);
	out.x /= module; out.y /= module; out.z /= module;
	return out;
}

point operator -(point a,point b){
	point out;
	out.x = a.x - b.x;
	out.y = a.y - b.y;
	out.z = a.z - b.z;
	return out;
}

point operator -(vertex a,vertex b){
	point out;
	out.x = a.x - b.x;
	out.y = a.y - b.y;
	out.z = a.z - b.z;
	return out;
}

point cross(point a,point b){
	point out;
	out.x = a.y*b.z-a.z*b.y;
	out.y = a.z*b.x-a.x*b.z;
	out.z = a.x*b.y-a.y*b.x;
	return out;
}

spoint c2s(vertex c)
{
	spoint s;
	s.rad = sqrt(c.x*c.x+c.y*c.y+c.z*c.z);
	if (fabs(s.rad)<ZERO) //点距离原点极近 将点置于原点
	{
		s.lat = s.lon = s.rad = 0.0;
	}
	else
	{
		s.lat = 90.0 - acos(c.z/s.rad)*180.0/Pi;
		s.lon = atan2(c.y,c.x)*180.0/Pi;
	}
	return s;
}

int main(int argc, char const *argv[]){
	vertex node;
	face triangle;
	vertexArray nodes;
	faceArray triangles;

	int temp_int,temp_int2;
	string temp_str;
	stringstream temp_ss;

	double attriMax = -1e+30;
	double attriMin = 1e+30;
	ifstream mshin("input2.msh");
	while(getline(mshin,temp_str)){
		if (!strcmp(temp_str.c_str(),"$Nodes")){
			getline(mshin,temp_str);
			temp_ss.str(""); temp_ss.clear(); temp_ss.str(temp_str);
			temp_ss >> temp_int;
			for (int i = 0; i < temp_int; i++){
				getline(mshin,temp_str);
				temp_ss.str(""); temp_ss.clear(); temp_ss.str(temp_str);
				temp_ss >> node.id >> node.x >> node.y >> node.z;
				nodes.push_back(node);
			}
		}
		else if (!strcmp(temp_str.c_str(),"$Elements")){
			getline(mshin,temp_str);
			temp_ss.str(""); temp_ss.clear(); temp_ss.str(temp_str);
			temp_ss >> temp_int;
			for (int i = 0; i < temp_int; i++){
				getline(mshin,temp_str);
				temp_ss.str(""); temp_ss.clear(); temp_ss.str(temp_str);
				temp_ss >> triangle.id >> temp_int2 >> temp_int2 >> temp_int2 
				>> triangle.vec[0] >> triangle.vec[1] >> triangle.vec[2];
				//triangle.vec[0] += 1; triangle.vec[1] += 1; triangle.vec[2] += 1;
				triangle.id += 1;
				triangles.push_back(triangle);
			}
		}
		else if (!strcmp(temp_str.c_str(),"$NodeData")){
			for (int i = 0; i < 8; i++)
				getline(mshin,temp_str);
			temp_ss.str(""); temp_ss.clear(); temp_ss.str(temp_str);
			temp_ss >> temp_int;
			for (int i = 0; i < temp_int; i++){
				getline(mshin,temp_str);
				temp_ss.str(""); temp_ss.clear(); temp_ss.str(temp_str);
				temp_ss >> temp_int2 >> nodes[i].attri;
				if(nodes[i].attri > attriMax) attriMax = nodes[i].attri;
				if(nodes[i].attri < attriMin) attriMin = nodes[i].attri;
			}
		}
		else continue;
	}
	mshin.close();

	for (int i = 0; i < nodes.size(); i++)
		nodes[i].attri = (nodes[i].attri - attriMin)/(attriMax - attriMin);

	for (int i = 0; i < triangles.size(); i++){
		triangles[i].outNor = normal(cross(nodes[triangles[i].vec[1]-1]-nodes[triangles[i].vec[0]-1],
			nodes[triangles[i].vec[2]-1]-nodes[triangles[i].vec[0]-1]));
	}

	ofstream objout("sphere.obj");
	objout << "mtllib global_topography.mtl" << endl << "o sphere" << endl;
	for (int i = 0; i < nodes.size(); i++){
		objout << "v " << setprecision(16) << nodes[i].x << " " << nodes[i].y << " " << nodes[i].z << endl;
	}
	for (int i = 0; i < nodes.size(); i++){
		objout << "vt " << setprecision(16) << nodes[i].attri << " 0.5" << endl;
	}
	for (int i = 0; i < triangles.size(); i++){
		objout << "vn " << setprecision(16) << triangles[i].outNor.x << " " << triangles[i].outNor.y << " " << triangles[i].outNor.z << endl;
	}
	objout << "usemtl earth-topo" << endl << "g model1" << endl << "s 1" << endl;
	for (int i = 0; i < triangles.size(); i++){
		objout << "f " << triangles[i].vec[0] << "/" << triangles[i].vec[0] << "/" << i+1 << " "
		 << triangles[i].vec[1] << "/" << triangles[i].vec[1] << "/" << i+1 << " "
		 << triangles[i].vec[2] << "/" << triangles[i].vec[2] << "/" << i+1 << endl;
	}
	objout.close();
	return 0;
}