#include <iostream>
#include <GL/glut.h>

#include <vector>

#define GLM_ENABLE_EXPERIMENTAL

#include <glm/glm.hpp>
#include <glm/ext.hpp>
#include <glm/gtx/string_cast.hpp>

typedef glm::vec3 point3;
// using point3 = glm::vec3


////////
struct triangle
{
    triangle() = default;

    triangle(const point3& pt1,
             const point3& pt2,
             const point3& pt3) : A(pt1), B(pt2), C(pt3){}
    point3 A, B, C;

};
//////////

point3 projekcija(const triangle& t, const point3& tocka)
{
    glm::vec3 vektor = tocka - t.A;

    const float distance = glm::dot(vektor,normal(t));
    std::cout<<distance;
    return tocka - distance*normal(t);
}
glm::vec3 normal(const triangle& t)
{
    const glm::vec3 v1 = t.B - t.A;
    const glm::vec3 v2 = t.C - t.A;
    const auto n = glm::cross(v1, v2);
    return glm::normalize(n); //normalize skracuje na duljinu 1
}
point3 teziste(const triangle& t)
{
    return (1.f/3.f)*(t.A + t.B + t.C);
}
std::vector<triangle> triangles;

void changeSize(int w, int h)
{
    if(h == 0) { h = 1;}

    float ratio = 1.0* w / h;

    glMatrixMode ( GL_PROJECTION );
    glLoadIdentity();
    glViewport ( 0, 0, w, h );
    gluPerspective ( 45,ratio,1,1000 );
}

void drawScene()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_MODELVIEW); // idemo u perspektivu
    glLoadIdentity(); // resetiranje
    gluLookAt(5.0, 4.0, -10.0, // camera
              0.0, 0.0, -1.0, // where
              0.0f, 1.0, 0.0); // up vector


    /////////
    glPointSize(5);
    for(const triangle& t : triangles)
    {
        glColor3f(1, 1, 1);
        glBegin(GL_LINE_LOOP);// crta poliliniju, zadnja i prva (tocka?) se spajaju
        glVertex3f(t.A.x, t.A.y, t.A.z);
        glVertex3f(t.B.x, t.B.y, t.B.z);
        glVertex3f(t.C.x, t.C.y, t.C.z);
        glEnd();
        glColor3f(0, 1, 1);
        const auto cg = teziste(t);
        const auto n = normal(t);
        glBegin(GL_POINTS);
        glVertex3f(cg.x, cg.y, cg.z);
        glEnd();
        glColor3f(1, 0, 0);
        glBegin(GL_LINES);
        glVertex3f(cg.x, cg.y, cg.z);
                glVertex3f(cg.x + n.x, cg.y + n.y, cg.z + n.z);
        glEnd();

        const auto pro = projekcija(t, tocka);
        glColor(0, 1, 0);
        glBegin(GL_LINES);
        glVertex3f(pro.x, pro.y, pro.z);
        glEnd();


    }


    /////////
    /*
    glBegin(GL_TRIANGLES);
    //Triangle
    glVertex3f(0.5f, -0.5f, 0.0f);
    glVertex3f(0.0f, 0.5f, 0.0f);
    glVertex3f(-0.5f, -0.5f, 0.0f);
    glEnd();
    */
    glutSwapBuffers();
}

int main(int argc, char **argv)
{


    ///////
    point3 pt1(0.5, -0.5, 0);
    point3 pt2(0., 0.5, 0);
    point3 pt3(-0.5, -0.5, 0);
    point3 pt4(0, 0.2, -1);
    point3 tocka(0, -0.5, 2);
    triangles.push_back(triangle(pt1, pt2, pt3));
    triangles.push_back(triangle(pt2, pt3, pt4));



    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE);
    glutInitWindowSize(400, 400);

    glutCreateWindow("v01 - p1");
    glutReshapeFunc(changeSize);
    glutDisplayFunc(drawScene);
    glutMainLoop();
    return 0;
}