CSG Basics-Endorsed Models Part 2.5

Hello there pranksters who were expecting a April Fool’s joke rather than an actual blog, WoodReviewer here, and thankfully the way everyone uses wood grain in-game is enough of a joke that I don’t have to make any. Originally, today was going to be a look at endorsed models that feature feature CSG modeling. However, after writing it up I realized too many people were unaware of what terms I were using might be, so I explained the basics of CSG and the blog go too long, so now I’m here with a special post focusing on the basics of CSG  so that people can understand the next blog. Now as a disclaimer, I don’t mess with CSG much. It crashes. A lot. And my time is too valuable to constantly clear out the hundreds of crash reports that get made, and I mean hundreds, so I hired a trained monkey to make all my CSG models. Now, I’m not sure what he makes since he sort of just mashes the keyboard, but I have faith he’ll eventually make something cool. Right now he just makes weird shapes and things that kind of look like bananas.  If it doesn’t work, I’ll have a trained monkey for sale. It’s a win-win.

Monkey CSG

My monkey’s latest work.


One thing to note is that I will not be using any advanced plugins; only Stravant’s Material Flip Plugin and whatever version of CmdUtl I feel like loading up. I will not be using any more advanced plugins to auto-CSG stuff or anything like that. Now, lets start with terms.

CSG-Abbreviation for Custom Solid Geometry.I think. Was never actually confirmed and I’m too lazy to look it up any more. The overall name for anything to do with manipulating the shape of parts.

Unions-When two parts are joined together

Negation-When a part is taken out of a second part. The parts that are removed are pink.

Separation-Separating a union into the original parts, which are parts, other unions, or negated parts.


Like regular bricks, when a union is made the texture is based on whatever direction the first brick selected is rotated. Look at the following image.

Texture Direction.png

Let me just explain this picture. On the left is a union where the bottom brick is selected first, and on the right the angled brick is. This can be done either by selecting them with the drag tool, or to be more precise, use Ctrl+left click to choose the order you select multiple bricks. Remember, the texture follows the direction of the first brick that was selected. However, lets say you already have a union, then what? You have two options.

The first is to union in an additional brick inside the union. I do not like that because it is harder to find the brick since it needs to be inside the union to not change the union, and it may cause artifacts then. You can do a similar trick shown below with negations.

Negation Fix.png

Same principle. Have the the wood brick going the way you want with the direction, negate it, and then union the negated brick with the other union. The negated brick does not need to be touching the previous union, and it should not create any artifacts. Should.


Believe it or not, that is everything on using wood grain with CSG. Everything. So how do people get wood grain so wrong with CSG? Because the use CSG when they shouldn’t. There are scenarios where no matter what you do you cannot union bricks together and expect the result to have proper wood grain. What are some examples?

Vertical and horizontal supports: If you have vertical and horizontal supports in an object, you cannot union it and have both supports maintain good wood grain.

Beam and Support.png

The first image is before the unions. The vertical support and the beam have proper wood grain. The next two are with first the beam, and then the support selected first for the union. Neither results produces a proper example of wood grain on both parts. This is why unioned tables and chairs are easy gotos for me to find bad wood grain.

This includes arches/curves. While in real life wood can bend and curves can be made, on ROBLOX the texture always goes straight and the curves do not form.

Arch None.png

That is a 90 degree arch with each brick rotated by 10 degrees. This looks OK, has some minor texture clipping, and is 10 parts in total. Now lets see what happens if we union it starting at the top.

Arch Top.png

The texture near the top is OK, but towards the bottom it becomes bad. Same happens if you start the union with the bottom brick.

Atch Bottom.png

Starts good, gets worse. But what if you start with a brick in the middle of the arch?

Arch Mid.png

It is good for a few sections, but gets bad near the ends. If you union it in sections of 3 it is OK.

Arch Sections.png

But now it looks very square and you loose a bunch of the  effect of having the arch be more than 10 bricks to start with.


“WoodReviewer, what you’ve said is a simple explanation of how textures work, and then explained why you can’t use CSG in some scenarios. How does this help me?”

You see Jimmy, there is no way to properly use ROBLOX’s wood grain on some CSG unions. None. It won’t work. Ever. Until ROBLOX allows curved textures, wood grain will not work on unions with curves. So what can you do? Avoid it. Unions and CSG lets builders do a bunch more than was possible before, but they can’t do everything. You as a builder have 10 years worth of tricks and techniques that you can use to get builds you look how you want. CSG is one technique, but not an end all and be all. Use it when it is applicable, and realize it has limits where you can’t use CSG. Can you use CSG to put a whole in the back of a wooden chair? Sure. Can you use it to union an entire wooden chair? No.

Know CSG’s limits, know when to avoid it, and you can easily have better wood grain in-game.

4 thoughts on “CSG Basics-Endorsed Models Part 2.5

  1. NWSpacek

    Your final picture is actually how unstressed curved beams are created. The outside of the curve is cut into the beam to form the curve, and the inside of the curve is either left flat (which you have done), or the piece cut off is put on the inside so that both sides have the curve. This is done a lot on wooden roller coasters.


  2. Pingback: CSG Issues-Endorsed Models Part 3 | WoodReviewerRBX

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