#include "sphere.h"
#include "glm/ext.hpp"
#include "phongmaterial.h"

#define M_PI 3.14159265358979323846
#define MAGIC_RATIO 0.37139f

Sphere::Sphere(Material* mat, int n)
{
    // icosahedron :
    addGroup(mat);
    Group* group = &(indiceGroups[0]);

    // top cap
    createVertex(0, 1);
    for(int i=0; i<5; i++)
        createVertex(i/5.f, 1-MAGIC_RATIO);

    // bottom cap
    createVertex(0, 0);
    for(int i=0; i<5; i++)
        createVertex((i+0.5f)/5.f, MAGIC_RATIO);

    // Compute faces
    for(int i=0; i<5; i++){
        int top = 1;
        int bottom = 7;
        int offset = (i+1)%5;
        // top cap
		addTriangle(0, top+i, top+offset);
        // bottom cap
		addTriangle(6, bottom+offset, bottom+i);
        // middle ribbon
		addTriangle(top+i, bottom+i, top+offset);
		addTriangle(top+offset, bottom+i, bottom+offset);
    }

    // geodesic subdivisions :
    for(int i=0; i<n; i++){
        edges = new Edge[positions.size()-1];
        int nb_triangles = group->indices.size()/3;
        for(int j=0; j<nb_triangles; j++)
        {
            int vid[3];
            for(int k=0; k<3; k++)
            {
                int idA = group->indices[j*3 + k];
                int idB = group->indices[j*3 + (k+1)%3];
                int a = idA < idB ? idA : idB;
                int b = idA > idB ? idA : idB;
                vid[k] = getEdge(a, b);
            }
            for(int k=0; k<3; k++)
                addTriangle(group->indices[j*3 + k], vid[k], vid[(k+2)%3]);
			addTriangle(vid[0], vid[1], vid[2]);
        }
        delete[](edges);
        group->indices.erase(group->indices.begin(), group->indices.begin()+nb_triangles*3);
    }
}

int Sphere::getEdge(int a, int b)
{
    Edge* current = edges+a;
    int vid = -1;
    while(vid == -1)
    {
        if(current->b == b)
            vid = current->vertex;
        else if(current->next == NULL)
        {
			vid = positions.size();
			// creating subdivision vertex
			glm::vec3 pos = glm::normalize(positions[a] + positions[b] / 2.f);
			addPosition(pos);
			addNormal(pos);

            // u/v sphériques, cohérents sur toute la sphère sauf des artefacts au niveau des u==0
			float newU = (pos.x < 0 ? 1.5f : 1.f) + atan(pos.z/pos.x)/(2*M_PI);
			float newV = acos(pos.y)/M_PI;
			addTexCoord(newU - floor(newU), newV);
            // alternative, u/v moyennés :
            //v.texCoord = (v0.texCoord + v1.texCoord)/2.f;

            // inserting the new vertex in the edge collection
            if(current->b == -1)
            {
                current->vertex = vid;
                current->b = b;
            }
            else
                current->next = new Edge(b, vid);
        }
        else
            current = current->next;
    }
    return vid;
}

void Sphere::createVertex(float u, float v)
{
		glm::vec3 pos(cos(u*2*M_PI)*sin(v*M_PI),
					  cos(v*M_PI),
					  sin(u*2*M_PI)*sin(v*M_PI));
		addPosition(pos);
		addNormal(pos);
		addTexCoord(u, v);
    }