Assignment no: 12
//Aim: Draw a line using OpenGL

#include <GL/glut.h>
#include <math.h>
#include <stdio.h>
const float PI=3.14;

void LineWithDDA(int x0,int y0,int x1,int y1)
{
    glPointSize(2.0);
    glBegin(GL_POINTS);
    glColor3f(0.0,0.0,0.0);

    int dx,dy,steps,i;
    float x,y;
    float xinc,yinc;

    dy=y1-y0;
    dx=x1-x0;
    y=y0;
    x=x0;
    if(abs(dx)>=abs(dy))
    {
        steps=dx;
    }
    else
    {
        steps=dy;
    }
    xinc=(float)dx/steps;
    yinc=(float)dy/steps;
    glVertex2d(x,y);
    for(i=1;i<steps;i++)
    {
        x+=xinc;
        y+=yinc;
        x0=floor(x);
        y0=floor(y);
        glVertex2d(x,y);
    }
    glEnd();
}

void init(void)
{
    glClearColor(1.0,1.0,1.0,0.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0,800,0,600,0,600);
}
void display(void)
{
    glClear(GL_COLOR_BUFFER_BIT);
    LineWithDDA(0,0,800,600);
    LineWithDDA(0,600,800,0);
    LineWithDDA(0,300,800,300);
    LineWithDDA(400,0,400,600);
    LineWithDDA(0,150,800,450);
    LineWithDDA(0,450,800,150);
    LineWithDDA(200,0,600,600);
    LineWithDDA(600,0,200,600);
    glutSwapBuffers();
}

int main(int argc, char** argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB);
    glutInitWindowSize(800,600);
    glutInitWindowPosition(100,100);
    glutCreateWindow("DDA Line Drawing!");
    init();
    glutDisplayFunc(display);
    glutMainLoop();
    return 0;
}

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#include <GL/glut.h>
#include <math.h>
#include <stdio.h>
const float PI=3.14;
int sign(float arg)
{
    if(arg<0)
    {
        return -1;
    }
    else if(arg==0)
    {
        return 0;
    }
    else
    {
        return 1;
    }
}
void LineWithBrasenham(int x1,int y1,int x2,int y2)
{
    glPointSize(2.0);
    glBegin(GL_POINTS);
    glColor3f(0.0,0.0,0.0);

    int s1,s2,exchange,y,x,i;
    float dx,dy,g,temp;
    dx=abs(x2-x1);
    dy=abs(y2-y1);
    x=x1;
    y=y1;
    s1=sign(x2-x1);
    s2=sign(y2-y1);
    if(dy>dx)
    {
        temp=dx;
        dx=dy;
        dy=temp;
        exchange=1;
    }
    else
    {
        exchange=0;
    }
    g=2*dy-dx;
    i=1;
    while(i<=dx)
    {
        glVertex2d(x,y);
        while(g>=0)
        {
            if(exchange==1)
            {
                x=x+s1;
            }
            else
            {
                y=y+s2;
            }
            g=g-2*dx;
        }
        if(exchange==1)
        {
            y=y+s2;
        }
        else
        {
            x=x+s1;
        }
        g=g+2*dy;
        i++;
    }

    glEnd();
}

void init(void)
{
    glClearColor(1.0,1.0,1.0,0.0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0,800,0,600,0,600);
}
void display(void)
{
    glClear(GL_COLOR_BUFFER_BIT);
    LineWithBrasenham(100,300,700,300);
    LineWithBrasenham(400,100,400,500);
    glutSwapBuffers();
}

int main(int argc, char** argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB);
    glutInitWindowSize(800,600);
    glutInitWindowPosition(100,100);
    glutCreateWindow("Brasenham Line Drawing!");
    init();
    glutDisplayFunc(display);
    glutMainLoop();
    return 0;
}