/*
 * File:   main_stepByStep.cpp
 * Author: polpe
 *
 * Created on February 10, 2014, 3:24 PM
 */

#include <cstdlib>
#include <iostream>

#include <gl/gl.h>
#include <gl/glu.h>
#include <glut.h>

#define MAXARRAYSIZE 100
#define MAXPTNUM 100

struct MyPoint
{
    double x,y;
    MyPoint() : x(0), y(0) {}
    MyPoint(int x, int y) : x(x), y(y) {}
};

//Töröttvonal egyes pontjainak x ill y koordinátáit tartalmazó tömb: (lehet máshogy is reprezentálni...)
int xcoord[MAXARRAYSIZE];
int ycoord[MAXARRAYSIZE];
int ptnum=0;
MyPoint ctrlpoints[MAXPTNUM];
double knotVector[MAXPTNUM];

//Ablakméret:
int wH=400;
int wW=400;

//Saját globális válzotók

//Ide írj, ha van saját inicializálási feladat
void SajatInit() {
}

float B(int i, float t)
{
    GLfloat Bi = 1.0;
    int j = 1;
    for(; j <= i; j++) Bi *= t * (ptnum-j)/j;
    for(; j < ptnum; j++) Bi *= (1-t);
    return Bi;
}

MyPoint CalcLagrangePoint (float t) {
    MyPoint actPT(0,0);
    for (int i = 0; i <= ptnum; i++)
    {
        actPT.x+=ctrlpoints[i].x*B(i,t);
        actPT.y+=ctrlpoints[i].y*B(i,t);
    }
    return actPT;
}

void drawLagrange()
{
    for (int i=0;i< ptnum;i++) {
        knotVector[i]=(double)i/(double(ptnum-1));
    }

    MyPoint a(0,0);
    MyPoint b(0,0);

    a = CalcLagrangePoint(0);
    for(double j = 0.01; j <= 1; j += 0.01)
    {
        b = a;
        a = CalcLagrangePoint(j);

        glBegin(GL_LINES);

        glVertex2d(b.x, b.y);
        glVertex2d(a.x, a.y);

        glEnd();
    }
}

//Újrarajzolás
void ReDraw( ) {
    //Fehér háttér:
    glClearColor(1.0, 1.0, 1.0, 0);
    glClear(GL_COLOR_BUFFER_BIT);


    //Fekete törtött vonal kirajzolása:
    glColor3d(0.0,0.0,0.0);
    glLineWidth(1);
    glLineStipple(1,0x3F0);

    glBegin(GL_QUADS);
    for(int i = 0; i < ptnum; i++)
    {
       glVertex2d(ctrlpoints[i].x+2,ctrlpoints[i].y+2);
       glVertex2d(ctrlpoints[i].x+2,ctrlpoints[i].y-2);
       glVertex2d(ctrlpoints[i].x-2,ctrlpoints[i].y-2);
       glVertex2d(ctrlpoints[i].x-2,ctrlpoints[i].y+2);
    }
    glEnd();

    glBegin(GL_LINES);
    drawLagrange();
    glEnd();

    glFlush( );
}





//Egér mozgára aktiválódik, kurzorpozíció koordinátáit kapja bemenetnek
void Motion(int x, int y) {

}


void MouseFunction(int button, int state, int x,int y)
{

    //bal gomb lenyomására
    if (button == GLUT_LEFT_BUTTON  && state == GLUT_DOWN) {
                ctrlpoints[ptnum].x = x;
                ctrlpoints[ptnum].y = y;
                ptnum++;
    }

    //jobb gomb lenyomására/felengedésére (lásd 2.2 feladat)
    if (button == GLUT_RIGHT_BUTTON) {

    }

    //A képernyő újrarajzolása (azaz redraw hívása)
    glutPostRedisplay();
}






void Keyboard(unsigned char key, int x, int y) {

}



//--------------------------
//  Keret (nem kell módosítani)

//Inicializálás
void Init(){
    glViewport(0, 0, wW, wH);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity( );
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity( );
    gluOrtho2D(0.0, wW, wH, 0.0);
    SajatInit();
}

//Ablak átméretezésekor a teljes képet skálázza
void reshape(int w, int h) {
    glViewport(0,0,(GLsizei)w,(GLsizei)h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0.0, wW, wH, 0.0);
    wW=w;
    wH=h;
}

int main(int argc, char* argv[])
{
    wW=400;
    wH=400;
    glutInitWindowSize(wW, wH);
    glutInitWindowPosition(100, 100);
    glutInit(&argc, argv);
    glutInitDisplayMode( GLUT_RGB );
    glutCreateWindow("DrawLine");
    Init();

    glutKeyboardFunc( Keyboard );
    glutDisplayFunc( ReDraw );
    glutMouseFunc(MouseFunction);
    glutMotionFunc(Motion);
    glutReshapeFunc(reshape);
    glutMainLoop();
}