Draw line between two points on console

Question

How can I draw a line on the console if I have a 2D array of chars. The function I want to write is something like:

This is my first attempt, but it looks totally wrong

public static void line(char[][] mPixels, int startRow, int startColumn, int endRow, int endColumn) 
{
    double dY = endRow - startRow;
    double dX = endColumn - startColumn;
    double slope = dX / dY;
    slope = Math.abs(slope);

    if(slope >= 1)
    {
        double progress = -(dY / dX);
        for(int i=startColumn; i<=endColumn; i++)
        {
            double j = startRow - (int) ((i-startColumn) * progress);
            int yLoc = (int) (Math.round( j * 100.0 ) / 100.0);

            mPixels[i][yLoc] = '*'; 
        }
    }

// print array  
}

May I suggest this awesome tool called google. Just search for it and find the wiki article. — ElKamina, Nov 13 '13 at 06:10
should add a rasterize, line ,DDA tag and delete those for loops tag they are not relevant for search — Spektre, Nov 13 '13 at 09:47

Spektre · Accepted Answer · 2018-10-10T08:01:46.950

use DDA or Bresenham,...

What you have looks like DDA but you do not handle slopes correctly. You should divide by the axis with bigger amount of pixels and use it as control axis so:

if |dx|>|dy| then for goes through x = x0 -> x1 and y=y0+((x-x0)*dy/dx)
if |dx|<|dy| then for goes through y = y0 -> y1 and x=x0+((y-y0)*dx/dy)
if they are equal then use any of above.
if dx==0 and dy==0 draw just dot and no for is present

Do not forget to handle if main axis is ascending or descending (can be x++,y++ or x--,y--) also can be done on integer only without division or multiplication but that is another story

Draw line between two points on console

1 Answers1