Lesson 2: Procedural map generation

This was actually the reason I decided to make this log, because I had just got my head around understanding some codes. What I wanted to do is see how much I can fiddle with writing some code - and I found myself having an interest in creating algorithms that generate random maps to be generally fun, and there was a bit of material on the subject already available in the forums.

I'm basing my work on something created by Gughunter (http://www.byond.com/ forum/?post=39230&hl=archipelago%20generator). Thanks to his demos I got to understand a few more things about coding too.

I followed his idea of dropping a seed (LandBot), and moving that LandBot around whilst creating a path of land behind it.

The twist I tried to make was that instead of painting land onto the sea by 1x1 tiles; I'm instead trying to draw pieces of land in blocks of 3x3, making the masses of land look slightly more congruent.

Here's what I did. If anyone has an idea how to make it better, feel free to post below too. I know I may be making mistakes in using common naming conventions - and if anyone can pick those up too and point it out to me, that'd be nice (it's not necessary though - I don't really publish professionally anyway).

Anyway, I put this line first because I needed to use this T variable later on in more than one proc (I've read that declaring too many variables slows the machine down - but I haven't figured out how to avoid doing some of these). I also saw how Gughunter used #define instead. I believe that's a more proper way of doing it, but I haven't really gotten into that practice yet heh :p



I next get my world proc to call a MapGen proc (following Gughunter). This was something I couldn't have figured out without looking at how Gughunter did it. I didn't understand at first how to call procedures up. I guess world then New() was the one I needed to start everything. Or at least I had trouble figuring out how to name the first proc that would be called. Calling other procs within other procs wasn't too difficult after that.

EDIT: I watched some videos about using Unity.. and I guess this would be equivalent to something like "void Start()". So I guess "world New()" sorts of starts off the chain of calling up the procedures..



.. My MapGen came next.. I used LandBot twice (I realise it's a crude way of doing it) so that I dropped the seeds that started drawing the pieces of land at possibly 2 random places. I was trying to get it to only run the second LandBot proc IF the total proportion of land to sea was below a certain percentage. But I haven't managed to do that yet. *Anyone know how?*. I meant to put other procs below LandBot in the future (such as a proc to make the borders of sea and land to be sand - like what Gughunter did). I haven't gotten that far in my self-study tutorial :p



..The LandBot proc itself comes next.. The formula looks pretty clunky because I had to make sure when my LandBot landed, it didn't start of too close to the sides of the map. Otherwise, my 3x3 block can't fit and nothing gets painted. In fact, I made it a bit variable in that I can adjust my brush size (BSize) above and make it 5x5 blocks or more.

What I did is drop the LandBot, move it, paint sea to land, move again, paint sea to land, move again, paint sea to land (repeated up to 7 times). It was either that, or drop the LandBot, paint sea to land, before making the first move.. but at the last cycle I would move and not paint. I was assuming it didn't make too much of a difference, so left it as it is below. (I also tried calling the CreateLand proc before I used for i<7 .. and the results looked similar)



.. Finally, my CreateLand proc looked for surrounding tiles and turned them into land if they were water. (or it was placing pieces of land on the water - with the water tiles still hidden beneath it *does that slow the machine down? How can I make it so that the water tile is replaced instead of merely overlapped?*). Anyway, it took me quite a while to find out that "in block" was probably what I needed, but I finally managed to get it right, and was quite glad I found it.

Oh yea, and looking at the codes below, I just realised I edited my brush size in this version to be random in nature. So it's not a fixed 3x3 brush I'm using to paint the tiles. It could be a 1x1 up to a 5x5 brush. I trialed and erred to come to the conclusion that the randomness of adding 3 random numbers ranging from 0 to 1 had a better distribution than 1 random number from 0 to 3 (I wanted the center of the distribution to occur more frequently).



And that's about it.. so if I ran the whole thing.. It sorts of worked and gave me some land area over a piece of sea. What I haven't figured out:

1) How to make the LandBot create more land only if the ratio of land turfs to water turfs is below a certain percentage.

2) How best to go through each tile, and check if there was water around it, and convert it into sand. I saw Gughunter doing this, but I'm trying to see if I can make it so that I replace it with a tile that actually is half in water, half in land, and a slim line of beach in between.

3) How to make it so that the sides of the map is painted too. Something about my algorithm is making my LandBot avoid the sides more often than I like. Haven't gone through it again to see just why that is.

4) How to resize the map. I know this is probably a trivial matter for some of you :p But I can't actually get my map size to be different from the default I get. I tried putting two lines of codes at the beginning.. .. but somehow the only effect they had was make my "turf = turf/water" line work. The size doesn't change. -> Go to the Map Editor by double clicking the dmm file, then Edit > Set Map Size




Anyway, my whole codes after Tutorial 1 and 2 currently look something like this (combining all those pieces above together).

I'm also a complete neophyte slowly (work is ramping up yet again -- halp!) immersing myself into DM, and I wanted to let you know that I enjoy and appreciate your efforts. It's very engaging!

Tsenses wrote:

.. How to do short, one-off clips of animations like punching, then revert back to your original icon state.

Going back over the map generation for Incursion got me to thinking, and I ended up stumbling across this article that blew my mind. I'm toying with the idea of trying to adapt the concept to redo Incursion, because frankly I've always been fascinated with the Voronoi tesselation and it'd be awesome to have more organic shapes--even more awesome if I could also get cool river and terrain shading out of it.

And if you think that condensed code is something, download the source for Runt or Scream of the Stickster: both of them made for 4K challenges.

I was thinking what I should fiddle with this weekend - and decided I'll try and figure out if I can look at mouse controls.

So what I'll try to learn to do these couple of days perhaps is to see if I can click somewhere on a map, and get my player character to turn towards it. Which I suppose means I need to learn:

i) How to detect where was clicked
-> I think it's under client/Click? (trying to read the the developer references under mouse control.

ii) How to calculate the angle between my player character and the place I clicked
-> I guess I'll need to remember some trigonometry? (or is there an easier way heh)

iii) Rotate the player character
-> I guess this should be easy given I've managed to rotate the character above.

Right.. so here starts my BYOND journey this weekend (and I probably won't finish by tomorrow lol)..

Ahh.. these were the exact feedback I was hoping for. I'm quite sure I'll be making noobish mistakes here and there.. So thanks for pointing them out and pointing me in the right direction to read up more about it. It really helps because I find there's so much information I need to learn and some direction certainly helps where to get going hehe..

Thanks again for the link - very much appreciated.

Edit: So I changed all the usr to src.. and everything still works as before.. I'm thinking this is to do with "subject verb object" of a sentence? So usr is the subject, src is the object?

So while I had "Make the player character rotate himself", I couldn't tell the difference because src and usr were both the player character. So in my earlier example, I couldn't write "Make the player rotate something else", unless I used src as I've been corrected to do. That makes sense now :p

Whenever you click something, client/Click() is called. It's a built-in verb. By default, it will see if you clicked on an atom, and if so it will call that atom's Click() proc. So if, say, you only want to respond to clicks on mailbox objects, you would write a proc for obj/mailbox/Click().

Other mouse procs do this same thing, finding which atom you're interacting with and calling a proc.

If you do override client/Click(), the reason you might call ..() is to use the default behavior. (You don't need to include the same arguments when you call ..()--they're included automatically.) So if you wanted to, say, output a message every time a player clicked, you might override client/Click() to do so, and then you'd call ..() to make sure the click was handled normally.

By the way: Even though something like obj/Click() is technically a proc, usr is usually valid there--because typically, these procs are only ever called by verbs such as client/Click(). Hence I call them pseudo-verbs.

Tsenses wrote:

Well, a bunch of issues with this:
1. I think I need to have turf/proc/Angle() instead of proc/Angle(), otherwise 'src' or wouldn't work..

Yes, that's correct--because in turf/Click(), src is the turf you clicked. When you call Angle(), unless it's a global proc it get called as src.Angle().

However, right off the bat you have a problem: You should not be using usr in the Angle() proc. It's bad practice to use the usr var in procs. I would suggest actually that Angle() be defined either as a global proc, or as an atom proc, and you send it the args you need.


The global Angle(A,B) is equivalent to B.AngleFrom(A).

2. If I set turf/proc, I can only call it in the Click() if I have turf/Click().. I couldn't get it to work with mob/Click() or anything else (do I need to somehow expose the procedure to it?)

That's why it'd be better to make it an atom proc (where it would belong to turfs and mobs alike), or global. Every object inherits procs and vars from its parent type. Turfs and mobs are both descended from atom. The hierarchy is like so:

3. The angles calculated range from 0 to 90.. whereas I'm trying to get it to tell me 0 to 360..

arctan() on its own will only ever range from -90° to 90°. What you need is a specialized proc, which I've written.

Now me, I prefer to deal with angles in a nautical format, where 0=north and it goes clockwise. If you use the mathematical convention where 0=east and it goes counterclockwise, the code would differ. Here's an atan2() snippet using the latter:


Therefore the angle from A to B would be atan2(B.x-A.x, B.y-A.y).

4. Oh, and it can't calculate if the rise over the run is 0/0.. do I need to use a bunch of IF functions? I totally forgot most of my trigonometry rules :p

Yep. You definitely need to handle division by 0 cases.

5. How do I get it to check the pixel position instead of game tiles? Or perhaps using pixel_x might be a bit more accurate..

If you're using pixel movement--that is, if you don't rely on gliding behavior and mobs have step_size defined--then you would use step_x and step_y in your calculations. Specifically:

I think it's great that both of you are doing this. It shows activity and positive progress. Don't be put off by the folks that are jumping in and derailing.

By the way, there's a new feature that makes it so that you can't see the posts of people you have pagerbanned and any replies to that person's post. It's actually really awesome, and it's allowed me to make this community a much more positive experience.