#Hey I have 130 enemies fruits doesnt

1 messages · Page 1 of 1 (latest)

near quest
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@dull plank @west crown Feel free to add

dull plank
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Hey!

near quest
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So you have a list of items, and you want to pick a random element from that list, but each element should have a different chance of being picked

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Right

dull plank
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Right

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I dont have a list yet but

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sure

near quest
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All theoretical right now

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So, instead of going for percentages, we start working with a concept called weights

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This is because we can't guarantee that all of our percentages sum up to 100%

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And realistically, a percentage can be expressed as a relation between the current and the other elements in the list

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So lets say, you have your enemies, (fruits) and you want 2 apples for every kiwi

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If you used percentages, you'd have a 66% chance for an apple and a 33% chance for a kiwi

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(we just ran into the first problem for percentages, since these sum up to 99%)

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We can instead express this the way I first said it, apples have a weight of 2 and kiwi's have a weight of 1

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Imagine these numbers in a long line with the lengths of each fruit being proportional to its weight

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So you'd have apples with length 2 and then kiwi's with length 1

dull plank
near quest
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What if we pick a random distance to walk down that line and then look at which fruit we arrive at?

dull plank
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I'm confused sorry, so the way you're trying to explain to me is that the fruits will have weights right?

near quest
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Yes

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Percentages are computed from the weights

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Weights are basically how common a specific item is relative to the others in the set

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Does that make sense?

dull plank
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Yes it does

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Now, i'll have to understand how to use them

dull plank
near quest
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Yes alright, using them is the most complex part

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Give me two seconds, ill try and draw something up

dull plank
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alright

near quest
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Say we want this as a distrution

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So for every kiwi, we will have 4 apples, 2 bananas and 3 grapefruits

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or in percentages (40%, 20%, 30%, 10%)

west crown
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put a yard stick and a ruler on the table, then pick a random point : you’re more likely to get the yard stick

dull plank
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Yep

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I get it

near quest
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So lets add all those numbers together

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We get 10 right?

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So what if, we then just pick a random number between 0 and 10?

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And walk next to our line

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and stop whenever we reach the right number

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So in this case, we do rng(0,10), which gives us 6

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if we walk the line till 6

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we will land on the border between banana and grapefruit

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but lets just say thats banana for now

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Does this still make sense?

dull plank
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Yes

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Its making sense

near quest
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Cool so in short

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  • We have a list of fruits, with their weights
  • We sum up the weights
  • We roll a number between 0 and the sum
  • We walk the line till we get to the randomly rolled number
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Do you think you could implement this in c#?

dull plank
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I mean well I get the concept

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But I wont be able to implement it yet

near quest
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I would give it a shot if I were you, and come back if you have a more specific problem

dull plank
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Right

near quest
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Feel free to just tag me or @west crown in this chat, im sure he'll probably even respond faster than I do. (also checking if I gave enough information)

dull plank
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well, I'm not used to theese advanced features, i checked your code in #💻┃code-beginner and its interesting, because I'm not understanding it in code form

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but let me figure it out

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just give me a bit more clue

near quest
dull plank
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oh

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well

near quest
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But you could try to understand it

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The steps are the same

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Just using a couple of these

west crown
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it has a few things that will be unfamiliar to novices

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one is that it's an extension method: it adds a new method to IEnumerable<T>

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(and thus, to anything that's derived from that, like List<T>)

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it's a static method whose first parameter has the this keyword

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it's very useful, and also what I do for this kind of thing

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for example

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    public static T Draw<T>(this IEnumerable<T> self)
    {
        return self.ElementAt(UnityEngine.Random.Range(0, self.Count()));
    }
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now I can do someList.Draw();

near quest
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And generics too

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:s

west crown
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ye

near quest
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really not beginner at all

west crown
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that just means it's not designed for one specific kind of thing

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in this case, it works for literally any type

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(very common for stuff with containers)

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the other big thing is that it takes a Func<T, float> parameter

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this is a function that takes T and returns a float

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it's what assigns the weights

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for example, here's my MinBy method...

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    public static T MinBy<T>(this IEnumerable<T> self, Func<T, float> metric)
    {
        if (self.Count() == 0)
            return default;

        float best = metric(self.First());
        T result = self.First();

        foreach (var elem in self)
        {
            if (metric(elem) < best)
            {
                best = metric(elem);
                result = elem;
            }
        }

        return result;
    }
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metric is a function that gives a float for each thing in the list

dull plank
west crown
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for example, to find the closest point in a list, I can do:

Vector3 point = // get this from somewhere
Vector3 closest = points.MinBy((other) => Vector3.Distance(point, other));
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and then, MaxBy is just...

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    public static T MaxBy<T>(this IEnumerable<T> self, Func<T, float> metric)
    {
        return self.MinBy(x => -metric(x));
    }
dull plank
west crown
dull plank
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well first != smallest but about that

near quest
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might be worth noting, you can pass functions to functions

west crown
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if metric is Vector3.Magnitude and you call this on a list of Vector3, it'll give you the shortest vector

west crown
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i don't have to write ten different functions to pick the smallest value in ten different ways

dull plank
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Well okay I get the concept

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Also, how much practive and time do i need to accomplish stuff like tthis?

near quest
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For now, ditch passing functions, ditch extension methods, ditch null-coelescing operators

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just make a function GetRandomEnemyByWeight()

dull plank
dull plank
near quest
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Does it work?

dull plank
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well, I dont know how to sum up the weights :I

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Yet

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I dont get what does it mean to sum up something here

near quest
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Do you have your enemy weights?

dull plank
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I have a list yes

near quest
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Or a list of your potential enemies?

dull plank
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I have a list of the weights

near quest
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Whats the type of the list? I assume it would be List<Enemy>() right?

dull plank
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The weights? Thoose are floats

near quest
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If you keep them seperate such as;

var enemies = new List<Enemy>();
var weights = new List<float>();

You have to be super careful that weights[index] corresponds to enemies[index]

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But that's not really important

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For now I would suggest you head to google and look up how to sum all values in a list :P

dull plank
dull plank
near quest
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I am assuming that you somewhere in your code has a list of prefabs that you can spawn

dull plank
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Not yet, that would be the next step

near quest
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I would do that first actually

dull plank
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I dont need thoose by the way

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Actually, it'll be just displayed in a text, because the "Fight" wont be visual

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Like number of enemies in general: XYZ
Number of type 1 enemies:
type2:

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etc.

near quest
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You'd still need a list of all the possible enemies that you could spawn right?

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If you want to be able to spawn them one by one that is

dull plank
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I dont think so I need to spawn them

near quest
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Alright lets not call it spawning then, lets call it incrementing the counter for taht enemy

dull plank
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Sure

near quest
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You want some sort of dictionary like this right:

var enemyWave = {
  'kiwi': 100,
  'apple': 20,
  'banana': 15
};
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You still need to know that you have kiwi, apple, banana as available enemies

dull plank
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Alright

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why vars?

near quest
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So lets say you don't use gameobjects for your enemies, and you want a super simple way to get all of the possible enemies, you could just hardcode it like this:

var enemies = new List<string>() {"kiwi", "Apple", "Banana"}

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var is just a shorthand

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so instead of having to write List<string> enemies = new List<string>() {"kiwi", "Apple", "Banana"}

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you just use var

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c# will automatically try to figure out what the type is supposed to be

dull plank
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Yeah but I cant declare it

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like that

near quest
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You can only use var if you directly assign a variable

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else c# wont know what type it is

dull plank
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So if you're passing value to an existing float for example?

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that way you can use vars?

near quest
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uhh I don't quite understand what you are trying to say

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Lets say you are calling a function, Vector3.Distance() for example

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It is defined to return a float

west crown
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var is used when declaring a variable, so I wouldn't expect anything to be already existing

dull plank
west crown
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this is not valid syntax

dull plank
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so am i a dummy

near quest
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therefore you can do

var distance = Vector3.Distance()

and C# will figure out that its a float

dull plank
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yeah well i thought

near quest
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Oh no I am very sorry about that

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It was not c# code

dull plank
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well at least i know whats a variable 😄

west crown
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notice how the declaration of weights has new() { /* stuff */ }

near quest
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I was typing psuedocode

dull plank
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yeah

west crown
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you can create a dictionary with default values in a similar way

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iirc it's...

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var weights = new() {
  { "kiwi", 100 }
};
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or was it square brackets

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i should go check this

dull plank
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What does the number refer to?

west crown
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indeed

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    Dictionary<string, float> map = new() {
        { "foo", 1 },
        { "bar", 3 }
    };
dull plank
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Well, and what does the float do there? 😄

west crown
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Dictionary<K, V> is a dictionary that has keys of type K and values of type V

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therefore

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Dictionary<string, float> looks up floats with string keys

west crown
near quest
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Also, if you declare a variable on class level, you always have to define the type. If you do it in a function you can use var

west crown
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indeed

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it's only valid on a local variable

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i.e. a variable declared inside of a function

dull plank
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Sure I'm watching some tutorials about lists and stuff like that to have a better understanding of whats going on before i start to make them

dull plank
west crown
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very hard to say

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i have like 12 years of experience with programming, in total

dull plank
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Right

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All the time all day long?

dull plank
west crown
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very intermittent

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i went to college for both computer science and chemistry

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i've been in grad school for CS for a while

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i only really got back into 3D game dev about 2 years ago

dull plank
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So i do have plenty of time

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May I ask how did you progress fast?

west crown
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the more experience you get with programming as a whole, the faster you can learn new things

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things become more and more intuitive

dull plank
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so tutorials are notit

west crown
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well, tutorials help you to do things that you can't figure out for yourself yet

dull plank
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you have to use what you have learned to actually learn them

west crown
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some things are just impractical to figure out on your own

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i am absolutely not figuring out how to write a custom post-processing pass in the URP on my own

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tutorials are also handy because they give you something that (if you follow the tutorial properly) works

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which means you can then modify it and, hopefully, get something else that works

dull plank
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well yeah but how do you progress effectively too?

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just make games

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and over the years you'll get better?

west crown
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pretty much

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when I ran into this exact problem -- weighted random draw -- I'd never implemented something exactly like it before

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but I could immediately think of an algorithm for it

near quest
# dull plank also, can you guys answer this one?

Hard to say, started programming about 10 years ago, mostly as something that looked interesting, ended up going to uni couple years later for software engineering, just finishing up a master's degree in AI. Learned a lot of different languages over the past few years, the more you program the more you realise that concepts and being able to understand them is more important than actually figuring out how to build them. As @west crown mentioned identifying a problem and then almost instantly coming up with an algo to solve it is the real skill here

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Working partime as a full stack software developer for a couple of years also helps

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Started with unity 2years ago I think

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When I started programming one of my first things that I made was a very shitty cookie clicker clone

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And slowly build it up to more complex projects, they usually have a lot of similar problems, just slightly different

dull plank
dull plank
near quest
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I don't work with unity for my job

dull plank
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I know

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but could you

near quest
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I don't think it's a very good career choice

dull plank
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Why not?

near quest
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It's just the industry, it is very focussed around selling a product and if the product dies down you lose your job

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There's also from what I've heard quite a bit of pressure

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Since you deal with normal people who won't understand why the release date was pushed for 2ore weeks

dull plank
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yeah

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but well , maybe thats what i'm gonna choose ,but i have plenty of time

west crown
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i'm considering trying to bust into the industry after i leave grad school

near quest
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You can always switch to game Dev or away from it

west crown
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i'm very good at going on the computer and typing

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but i've already had reasonable success from solo work

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it's a tough business, for sure

near quest
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Sounds hard to find a job though, such a niche

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Where as I can literally call up 10 companies and have atleast 5 offers in 2 weeks

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For software development that is

dull plank
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yeah well thats true

near quest
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But by the sounds of it, you still have to go to college and stuff right?

west crown
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downside: you might have to touch an electronic medical record system

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fear

near quest
west crown
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i need to try doing that properly one year

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i've done a few days a few times

near quest
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Ah I see, they good fun, very specific kind of problem solving though

dull plank
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here you can go to special 6 grade colleges. and i didnt know what to do in 7th so i signed up and got in here.

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so no learning from professors for the next 3 years at least

near quest
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School systems are very different over here, I don't quite know what 6th, 7th grade and stuff are

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We pick something at age of 17-18

dull plank
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wdym you pick something?

near quest
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To do our bachelor's in, before that it's highschool stuff

dull plank
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ah yes sure. so well, i've done this little battle system here, I'll make the weights later. Can you check why are the attackers and the defenders are 0?

https://paste.ofcode.org/UPiVyiXSsSAcHBikzAJmJ - This controls the batlle but its not really relevant because the function doesnt actually occur because the values are 0.

https://paste.ofcode.org/8nmyxJfKmjQCX4UEx3RkYJ - And this when you click on "battle".

If I debug the kangarooenemies and the count it increases and its okay, but the index integers are 0

@near quest

near quest
dull plank
near quest
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but the index integers are 0

What exactly do you mean by this?

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@dull plank

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What do you want (expect) to happen?
What is currently happening?

Then we can answer why it is happening

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Also, allow me to introduce the switch statement

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probably cut your code down in half using that

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And make it easier to read / maintain

dull plank
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Hey @near quest I'm not at home and I'm sorry because I didnt answer, now I:m following through some full game tutorials so maybe I can figure it on my own after thoose

near quest
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Gotcha, if it is still relevant to this then you could post here bit at this point you might get help a lil bit quicker from the normal channel