How to plot a circular X Y graph using nested for loops

Question

I'm trying to plot a circular X/Y graph using 2 for loops, but can't figure out the algorithm to make it circular instead of squared.

I currently have 2 nested for loops but this makes a 5 by 5 square. Is there anything I can add that would make the box circular instead? Preferabbly with a slight randomisation.

For some context I'm trying to learn the basics of procedural generation, and am trying to implement biome types into a 2d map I am randomly generating.

Thank you!

//my code has a for loop which runs the whole sequence several times
for ($i=0; $i<$x; $i++) {

    // select a random tile from the database to use as the center of the grid
    ${'qt'. $i} = $db->query("SELECT x,y,level,type,biomecenter FROM bmmap WHERE biomecenter=0 ORDER BY RAND() LIMIT 1");
    ${'rt'. $i} = ${'qt'. $i}->fetch_assoc();

    // draw the grid around the center tile
    for ($tx=${'rt'. $i}['x']-5; $tx<=${'rt'. $i}['x']+5; $tx++) {
        for ($ty=${'rt'. $i}['y']-5; $ty<=${'rt'. $i}['y']+5; $ty++) {
            // plot the square
        }
    }
}

I'm updating a field in the database for the relevant square. I thought the code was irrelevant so I didn't include it $db->query("UPDATE bmmap SET type='rock' WHERE x=".$tx." AND y=".$ty); — Joshua 'J-Dawg' Oakley, Apr 03 '17 at 21:37
No, I mean what are you using that displays the circle. HTML5 canvas, SVGs, or something else? — DiddleDot, Apr 03 '17 at 21:40
I'm just using html table where each corresponds with an X,Y coordinate in my database — Joshua 'J-Dawg' Oakley, Apr 03 '17 at 21:43
Have a look at the `sin()` and `cos()` functions: http://php.net/manual/en/ref.math.php (Hint, there's an example at the end of the `sin()` page). — KIKO Software, Apr 03 '17 at 21:46
Thank you. The sin/cos functions seem to do the trick. I used the example on the page but the circles aren't filled in though, they're just outlines. Do you have any idea how to change that? — Joshua 'J-Dawg' Oakley, Apr 03 '17 at 22:01

How to plot a circular X Y graph using nested for loops

0 Answers0