#include<bits/stdc++.h>

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

typedef struct p Point;

struct p{
    float x, y;
    p(float x,float y)
    {
        this->x = x;
        this->y = y;
    }
    Point operator=(const Point& p)
    {
        this->x = p.x;
        this->y=p.y;
    }
    void inc(float xi,float yi)
    {
        this->x+=xi;
        this->y+=yi;
    }
    void print()const
    {
        std::cout<<x<<" " <<y<<std::endl;
    }
};

Point A(10,20),B(30,50);

std::vector<Point> dda()
{
   std::vector<Point> ret;
    int dx = B.x-A.x;
    int dy = B.y - A.y;
    int step = std::max(dx,dy);

    float xInc = dx*1.0/step;
    float yInc = dy*1.0/step;

    Point temp = A;

    for(int i=0; i<step; i++)
    {
        temp.inc(xInc,yInc);
        ret.push_back(temp);
        temp.print();
    }

    return ret;
}

void display(void)
{
    /* clear all pixels */
    glClear (GL_COLOR_BUFFER_BIT);
    /* draw white polygon (rectangle) with corners at
    * (0.25, 0.25, 0.0) and (0.75, 0.75, 0.0)
    */
    glColor3f (1.0, 0.25, 1.0);
    glBegin(GL_POINTS);

    std::vector<Point> points = dda();

    for(const auto& p:points) {
        glVertex3f(p.x,p.y,0);
    }

    glEnd();
    /* don't wait!
    * start processing buffered OpenGL routines
    */
    glutSwapBuffers();
}



void init (void)
{

    glClearColor (0.0, 0.0, 0.0, 0.0);   // Background Color
    glMatrixMode(GL_PROJECTION);        /* initialize viewing values */
    glLoadIdentity();
    glOrtho(0.0, 100.0, 0.0, 100.0, -1.0, 1.0); // To specify the coordinate & Specify the distances to the nearer and farther depth
}

/*
* Declare initial window size, position, and display mode
* (Double buffer & RGBA). Open window with "hello"
* In its title bar. Call initialization routines.
* Register callback function to display graphics.
* Enter main loop and process events.
*/


int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB); //Double Frame
    glutInitWindowSize (500, 500);
    glutInitWindowPosition (200, 200);
    glutCreateWindow ("DDA");
    init ();
    glutDisplayFunc(display);
    glutMainLoop();

    return 0; /* ISO C requires main to return int. */
}