lab1.cpp

#include<bits/stdc++.h>
#include<GL/glut.h>
using namespace std;

GLint X1,Y1,X2,Y2;

void LineBres(void)
{
	glClear(GL_COLOR_BUFFER_BIT);
	int dx=abs(X2-X1),dy=abs(Y2-Y1);
	int p=2*dy-dx;
	int twoDy=2*dy,twoDyDx=2*(dy-dx);
	int x,y;
	if(X1>X2)
	{
		x=X2;
		y=Y2;
		X2=X1;
	}
	else
	{
		x=X1;
		y=Y1;
	}
	glBegin(GL_POINTS);	
	glVertex2i(x,y);
	while(x<X2)
	{
		x++;
		if(p<0)
			p+=twoDy;
		else
		{
			y++;
			p+=twoDyDx;
		}
		glVertex2i(x,y);
	}
	glEnd();
	glFlush();
}

void Init()
{
	glClearColor(1.0,1.0,1.0,0);
	glColor3f(0.0,0.0,0.0);
	glPointSize(8.0);
	glViewport(0,0,50,50);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(0,50,0,50);
}

int main(int argc,char **argv)
{
	cout << "Enter two points for drawing line Bresenham:\n";
	cout << "\n enter points (X1,Y1): ";
	cin >> X1 >> Y1;
	cout << "\n enter points (X2,Y2): ";
	cin >> X2 >> Y2;
	
	glutInit(&argc,argv);
	glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
	glutInitWindowSize(500,500);
	glutInitWindowPosition(0,0);
	glutCreateWindow("BRESENHAM'S LINE ALGO");
	Init();
	glutDisplayFunc(LineBres);
	glutMainLoop();
	return 0;
}