bressenhamsLineDrawing.cpp

#include <iostream>
#include <graphics.h>
// code from Geeksfromgeeks
//Uncomment the graphics library functions if you are using it
using namespace std;

void plotPixel(int x1, int y1, int x2, int y2, int dx, int dy, int decide)
{
	//pk is initial decision making parameter
	//Note:x1&y1,x2&y2, dx&dy values are interchanged
	//and passed in plotPixel function so
	//it can handle both cases when m>1 & m<1
	int pk = 2 * dy - dx;
	for (int i = 0; i <= dx; i++)
	{
//		cout << x1 << "," << y1 << endl;
        putpixel(x1, y1, WHITE);
		//checking either to decrement or increment the value
		//if we have to plot from (0,100) to (100,0)
		x1 < x2 ? x1++ : x1--;
		if (pk < 0)
		{
			//decision value will decide to plot
			//either x1 or y1 in x's position
			if (decide == 0)
			{
			// putpixel(x1, y1, RED);
				pk = pk + 2 * dy;
			}
			else
			{
				//(y1,x1) is passed in xt
			// putpixel(y1, x1, YELLOW);
				pk = pk + 2 * dy;
			}
		}
		else
		{
			y1 < y2 ? y1++ : y1--;
			if (decide == 0)
			{

				//putpixel(x1, y1, RED);
			}
			else
			{
			// putpixel(y1, x1, YELLOW);
			}
			pk = pk + 2 * dy - 2 * dx;
		}
	}
}

int main()
{
 int gd = DETECT, gm;
 initgraph(&gd, &gm, "xxx");
	int x1 = 100, y1 = 110, x2 = 300, y2 = 120, dx, dy, pk;
	//cin cout
	dx = abs(x2 - x1);
	dy = abs(y2 - y1);
	//If slope is less than one
	if (dx > dy)
	{
		//passing argument as 0 to plot(x,y)
		plotPixel(x1, y1, x2, y2, dx, dy, 0);
	}
	//if slope is greater than or equal to 1
	else
	{
		//passing argument as 1 to plot (y,x)
		plotPixel(y1, x1, y2, x2, dy, dx, 1);
	}
 getch();
}