Bresenham Line Drawing - OpenGL

bresenham.cpp

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

int x1, y1, x2, y2;

void myInit() {
	glClear(GL_COLOR_BUFFER_BIT);
	glClearColor(0.0, 0.0, 0.0, 1.0);
	glMatrixMode(GL_PROJECTION);
	gluOrtho2D(0, 500, 0, 500);
}

void draw_pixel(int x, int y) {
	glBegin(GL_POINTS);
	glVertex2i(x, y);
	glEnd();
}

void draw_line(int x1, int x2, int y1, int y2) {
	int dx, dy, i, e;
	int incx, incy, inc1, inc2;
	int x,y;

	dx = x2-x1;
	dy = y2-y1;

	if (dx < 0) dx = -dx;
	if (dy < 0) dy = -dy;
	incx = 1;
	if (x2 < x1) incx = -1;
	incy = 1;
	if (y2 < y1) incy = -1;
	x = x1; y = y1;
	if (dx > dy) {
		draw_pixel(x, y);
		e = 2 * dy-dx;
		inc1 = 2*(dy-dx);
		inc2 = 2*dy;
		for (i=0; i<dx; i++) {
			if (e >= 0) {
				y += incy;
				e += inc1;
			}
			else
				e += inc2;
			x += incx;
			draw_pixel(x, y);
		}

	} else {
		draw_pixel(x, y);
		e = 2*dx-dy;
		inc1 = 2*(dx-dy);
		inc2 = 2*dx;
		for (i=0; i<dy; i++) {
			if (e >= 0) {
				x += incx;
				e += inc1;
			}
			else
				e += inc2;
			y += incy;
			draw_pixel(x, y);
		}
	}
}

void myDisplay() {
	draw_line(x1, x2, y1, y2);
	glFlush();
}

void main(int argc, char **argv) {

	printf( "Enter (x1, y1, x2, y2)\n");
	scanf("%d %d %d %d", &x1, &y1, &x2, &y2);

	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
	glutInitWindowSize(500, 500);
	glutInitWindowPosition(0, 0);
	glutCreateWindow("Bresenham's Line Drawing");
	myInit();
	glutDisplayFunc(myDisplay);
	glutMainLoop();
}

How to compile

hii yogi1110
just compile by using following command...

g++ filename.c -lglut -lGL -lGLEW -lGLU -o filename
use need to give extension as .c to your file and also check that is it working with .cpp

Use
g++ BresenhamsLine.cpp -framework OpenGL -framework GLUT
for compile and run using ./a.out

it is not working in codeblocks what to do

thanks for that

its not working in codeblocks. its says stopped working

you code doesn't return anything...it will work just by either altering to this..

main(int argc, char **argv) {/

Can you try this - https://github.com/nowke/cg_lab/tree/master/1_bresenham_line ?

how to use glfw+glad to do it??

I want to plot a pixel after 4 sec. How can I do this ?

Using a sleep command