Grid Placement System

DerpPikachu26 · August 18, 2021, 9:15pm

I am trying to make a grid placement system, but I am not sure how I could do this. Could anybody help me? (I am not looking for code, but on HOW I could write the code for this system myself)

Thanks!

nicemike40 · August 18, 2021, 9:47pm

Here’s a great article about creating a robust placement system:

github.com

EgoMoose/Articles/blob/master/Misc/Furniture Placement System.md

> This guide was originally written for [scriptinghelpers ](https://scriptinghelpers.org/). The original can be found [here ](https://scriptinghelpers.org/blog/creating-a-furniture-placement-system).

One of the most common requests I get for blog post topics are for a decoration placement system that saves. I’ve shied away from this topic in the past as there is no singular “correct” way to do it. That being said, I think it's a good exercise for all game devs to go through and will potentially place a role in a future blog post I plan to write.

In addition to change things up, I’ll also take the time to explain and use Object Oriented Programming (OOP) as it’s not only my own preferred style, but also something Roblox uses for their core scripts.

## Object Oriented Programming

OOP is all about writing classes which in this context is a very fancy synonym for the word “blueprint”. We can then use these blueprints to create objects that have certain properties and methods.

If some of these words sound familiar to you, well, that’s because they are. The objects that you interact with such as `Parts`, `Humanoids`, `Motor6Ds`, and so forth are by design of the OOP paradigm. These objects have properties and methods that when combined define how they interact with our game.

Properties are used to define “characteristics” of an object. For example, a `Part` has a property called `Size` which as its name suggests defines how large or small the object is. In turn these properties often play a role in the behaviour and actions associated with said object which is defined by methods. For instance, the method `:GetMass()` returns the mass of the part which among other things varies with size. Thus, we can see an example of a clear connection here between methods and properties.

Now that we have some of the terminology down and an example I’d like to further discuss the distinction between classes and objects. A class defines the properties and methods that an object will have. For example, we know all parts are going to have a position property, so we define it in our class. The actual value of the position property will vary between individual objects, but the overarching concept of a part we know will have a property called `Position` with a `Vector3` as its value. In a similar sense when writing the methods of our class we may not know the literal values for each property, but since we know that those values will exist, we can treat them almost like function parameters.

The difference between OOP and a more functional approach for the same task can be seen in the code sample below.

```Lua
local part = Instance.new("Part")

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XD_Destroyer1234 · August 18, 2021, 9:49pm

you could try UiGridLayout, see if its what you’re looking for. it was a solution for me

DerpPikachu26 · August 18, 2021, 9:50pm

Thanks a lot, I’ll check it out!

DerpPikachu26 · August 18, 2021, 9:53pm

I’ll try it out, thanks. Also is it on the Developer Page?

XD_Destroyer1234 · August 18, 2021, 9:56pm

yeah here UIGridLayout | Roblox Creator Documentation

DerpPikachu26 · August 18, 2021, 9:58pm

oh okay, thanks a lot for the help!

Prototrode · August 18, 2021, 10:01pm

What exactly are you looking for here? Grid placement like building voxels in the workspace or organizing GUI into a grid-like fashion?

DerpPikachu26 · August 18, 2021, 10:02pm

I am looking for a grid placement system similar to the one in Roblox Bedwars.

DerpPikachu26 · August 18, 2021, 10:04pm

I have looked at the article, and it helped a lot. But I have one issue though, it is that I am trying to make a placement system similar to the Roblox Bedwars Game(game link here), the article helped me understand a lot more about grid systems, but how would I be able to make it where you could place blocks anywhere across the map and over the void or where nothing is under the block being placed? (Sorry if the article said anything about it and I missed it)

Thanks!

Prototrode · August 18, 2021, 10:07pm

If all of the blocks are the same size, you can try using raycasts. Cast a ray from the player’s camera to the player’s cursor position (Mouse.Hit); gather information from the RaycastResult and use the surface normal to offset the block by exactly one voxel.

To simplify:

You use raycast to identify the block the player is looking at.
You use the surface normal to identify which side of the block the player is looking at.
Using the surface normal (which is a Vector3), you can calculate the position of the placed block.

DerpPikachu26 · August 18, 2021, 10:10pm

Oh okay thanks, that helps a lot. I do have all the blocks at the same size, but if they were in a model, would it still work? (Sorry, I am still pretty new to coding)

Prototrode · August 18, 2021, 10:12pm

You want to make sure that the raycast picks up the voxel itself and not some of the individual parts in the model. For detailed blocks like those, you can try encasing them in an invisible cube which acts like the voxel.

DerpPikachu26 · August 18, 2021, 10:13pm

Okay, thanks for the help, I’ll try writing this code and if I have anymore questions I’ll come back and ask.

Prototrode · August 18, 2021, 10:15pm

I found this thread which can help:

DerpPikachu26 · August 18, 2021, 10:16pm

I’ll check it out, thanks for all the help!