Interpolation between two points on a grid. The resulting points from iteration can be imagined as hitting all pixels on a screen that intersect a line that's drawn from any pixel to any pixel on the screen.

Veclerp.java

public class Veclerp
{

    public int x, y;
    private int x_inc, y_inc, dx, dy, error, n;

    public void start( int x0, int y0, int x1, int y1 )
    {
        dx = Math.abs( x1 - x0 );
        dy = Math.abs( y1 - y0 );
        x = x0;
        y = y0;
        n = 1 + dx + dy;
        x_inc = (x1 > x0) ? 1 : -1;
        y_inc = (y1 > y0) ? 1 : -1;
        error = dx - dy;
        dx *= 2;
        dy *= 2;
    }

    public boolean next()
    {
        if ( error > 0 )
        {
            x += x_inc;
            error -= dy;
        }
        else
        {
            y += y_inc;
            error += dx;
        }

        return --n > 0;
    }

    public boolean atEnd()
    {
        return n == 0;
    }
}