#include "glut.h"
#include <cstdio>
#include <iostream>
using namespace std;
GLUnurbsObj* nobj;

struct pos
{
    float x, y, z;
};


int degree = 3;
int knotSize = 7;
    GLfloat knot[20];

  //  int pointCount = 4;
//GLfloat ctlarray[][3] = {{-0.9, -0.8, 0.0}, {-0.2, 0.8, 0.0}, {0.2, -0.5, 0.0}, {0.9, 0.8, 0.0}};

    int pointCount = 8;
GLfloat ctlarray[][3] = {{-0.9, 0.3, 0.0}, {-0.8, 0.8, 0.0}, {-0.5, 0.6, 0.0}, {-0.4, -0.3, 0.0}, {0.0, -0.6, 0.0}, {0.4, -0.3, 0.0}, {0.7, 0.8, 0.0}, {0.9, 0.8, 0.0}};



void generateKnot()
{
    int k = degree + 1;
    int n = pointCount - 1;
    for (int i = 1; i <= n + k + 1; ++i)
    {
        if (i <= k)
        {
            knot[i - 1] = 0;
        }
        else
            if(i <= n + 1)
            {
                knot[i - 1] = i - k;
            }
            else
            {
                knot[i - 1] = n - k + 2;
            }
            std::cout << knot[i] << " ";
    }
    cout << endl;
    knotSize = n + k + 1;

}


void init(void)
{
    glClearColor(1.0, 1.0, 1.0, 1.0);
    nobj = gluNewNurbsRenderer();
    gluNurbsProperty( nobj, GLU_SAMPLING_TOLERANCE, 25.0);
}

void motFunction(int x, int y)
{
    ctlarray[4][0] = x / 100.0 - 4;
    ctlarray[4][1] = 4 - y / 100.0;
    glutPostRedisplay();

}


void Display()
{

    glClear(GL_COLOR_BUFFER_BIT);
    glLineWidth(3.0);
    glColor3f(0.0, 0.3, 1.0);


    degree = 1;
        generateKnot();
        gluNurbsCurve(nobj, knotSize, knot, 3, &ctlarray[0][0], degree + 1, GL_MAP1_VERTEX_3);
        glColor3f(1.0, 0.3, 1.0);
        degree = 3;
        generateKnot();
        gluNurbsCurve(nobj, knotSize, knot, 3, &ctlarray[0][0], degree + 1, GL_MAP1_VERTEX_3);


    glPointSize(4.0);
    glColor3f(0.0, 0.0, 1.0);
    glBegin(GL_POINTS);
    for (int i = 0; i < pointCount; ++i)
        glVertex3fv(ctlarray[i]);
    glEnd();
    glFlush();
}


int main()
{

    glutInitDisplayMode(GLUT_RGBA | GLUT_SINGLE);
    glutInitWindowSize(800, 800);
    glutInitWindowPosition(0,0);
    glutCreateWindow("bezier");
    init();
    glutDisplayFunc(Display);
    glutMotionFunc(motFunction);
    glutMainLoop();


    return 0;
}