CG 1 - BRESENHAM’S LINE ALGORITHM

1. Implement Bresenham’s line drawing algorithm for all types of slope.

#include<stdio.h>
#include<math.h>
#include<iostream>
#include<GL/glut.h>

int xstart, ystart, xend, yend;
void init()
{
gluOrtho2D(0, 500, 0, 500);
}

void draw_pixel(int x, int y)
{
glColor3f(1, 0, 0);
glBegin(GL_POINTS);
glVertex2i(x, y);
glEnd();
glFlush();
}

void LineBres(int xstart, int ystart, int xend, int yend)
{
int dx = abs(xend - xstart);
int dy = abs(yend - ystart);
int twody = 2 * dy, twodyminusdx = 2 * (dy - dx);
int p = 2 * dy - dx;
int x, y;
if (xstart > xend)
{
x = xend;
y = yend;
xend = xstart;
}
else
{
x = xstart;
y = ystart;

}
draw_pixel(x, y);
while (x < xend)
{
x++;
if (p < 0)
p += twody;
else
{
y++;
p += twodyminusdx;
}
draw_pixel(x, y);
}
}

void Display()
{
glClear(GL_COLOR_BUFFER_BIT);
glClearColor(0, 0, 0, 1);
LineBres(xstart, ystart, xend, yend);
glEnd();
glFlush();
}

int main(int argc, char** argv)
{
printf("Enter (x1, y1, x2, y2)\n");
scanf("%d%d%d%d", &xstart, &ystart, &xend, &yend);
glutInit(&argc, argv);
glutInitWindowPosition(50, 50);
glutInitWindowSize(500, 500);
glutCreateWindow("Bresenham's Line Drawing");
init();
glutDisplayFunc(Display);
glutMainLoop();
return 0;
}

OUTPUT :

( click on image to zoom )