#include <GL/glut.h>

void init() {
	// set matrix mode to PROJECTION mode
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(0,200,0,200);
	
	
}

void drawPoint(int x, int y) {
	glBegin(GL_POINTS);
		glColor3f( 1.0f, 1.0f, 1.0f );
		glVertex2i(x,y);
	glEnd();
}

void midpoint( int x0, int y0, int x1, int y1 ) {
	int dx, dy, incrE, incrNE, d, x, y;
	
	dx = x1-x0;
	dy = y1-y0;
	d = 2*dy - dx;
	incrE = 2*dy;
	incrNE = 2 * (dy - dx);
	
	x = x0;
	y = y0;
	
	drawPoint(x,y);
	while( x < x1 ) {
		if ( d <= 0 ) {
			x++;
			d += incrE;
		} else {
			x++;
			y++;
			d += incrNE;
		}
		drawPoint(x,y);
	} 
	
	
}

void drawLine() {
	//delete buffers
	glClear(GL_COLOR_BUFFER_BIT);
	midpoint(10, 10, 170, 130);

}

void keyboard(unsigned char key, int x, int y) {
	switch(key) {
		case 27: 
			exit(0);
			break;
	}
}

// Called to draw scene
void RenderScene(void)
	{
	// Clear the window with current clearing color
	glClear(GL_COLOR_BUFFER_BIT);
	
	drawLine();

	// Flush drawing commands
	glFlush();
	}


// Setup the rendering state
void SetupRC(void)
    {
    // Set clear color to black
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
	
	

    }




// Main program entry point
int main(int argc, char* argv[])
    {
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutInitWindowSize(100,100);
	glutInitWindowPosition(20,20);
	
	glutCreateWindow("Points");
	SetupRC();
	
	init();
	glutDisplayFunc(RenderScene);
	glutKeyboardFunc(keyboard);
	

	

	glutMainLoop();

	return 0;
    }