Tips on CSG (Solid) modeling?

[TheUltimateLifeFormU (allegro_pacific)]

Okay, this may sound like I am new to CSG modeling (Solid Modeling) but trust me I’m really not, I’ve been doing solid modeling for quite a while now thanks to this old tutorial

If i put this in the wrong category please tell me where to move it because I feel like I put it in the wrong place if im not mistaken

How-to: Solid Modeling Basics

However I have had some trouble with this convenient method of 3d modeling which caused me to refrain from using it and turning to my beloved meshes

(Note: I primarily use CSG to create somewhat detailed models of vehicles, buildings, other stuff, like decorations)

My biggest fear: curves

Lets say I’m modeling a car, bus or a train. I’ll do train in this case because thats what i mostly use CSG to do out of vehicles i made

Most trains in this world have a level of curvature to them and I wanted to know how to achive such goodness. Here are some examples of what I wish to achieve

EXAMPLES FROM MIND THE GAP Mind the Gap - Roblox

Judging from my level of experience, I’d never be able to do something like that, when i do curves lets make the head of the train that corves in an arc, i place a bunch of parts and rotate them accordingly but when i negate + union them together

Sometimes I would see weird chunks of stuff that didn’t negate or chunks that look weird and just sticks out of the model im trying to make which makes it look weird. I remember when i first started i tried to make this locomotive

as you can see theres many levels of curvature here in which when i tried to make it myself, i had trouble, i reached triangle limit my program crashed a lot. So i wanted to know if there are good ways to do curving good.

Another example would be the BR Class 442 by Wessex Electrics

its extremely round here and i tried to make this one time and the curvature was a pain to model. Especially when the parts im trying to negate with obstruct my view preventing me from seeings the shape im going to make before i do make it. Transparency doesn’t help either, ESPECIALLY when i have a reference image in the background

(Im also using this to make bogies, undercomponents, etc)

Im sorry if my explanation was bad, im not the best at explaining things, let me know if you need more information, thank you

And then we have texturing. Okay so like the mind the gap images the textures look very good. Apparently they seem like decals. So i try to do that and apparently the decal ends up wierd, its stretched too much to the point where it doesn’t fit well? Would I use decals? Or is there a better way to make CSG liveries?

And finally interiors. How would I do that, never made interiors so i need tips, thank you

[TheUltimateLifeFormU (allegro_pacific)]

I dont know what happened but the thing sent before i could even finish, so give me time to edit this

Edit: Finished, let me know if you need more information

[Scottifly]

Unions are very messy to deal with. Like you’ve noticed it’s almost impossible to make compound curves. You can use Unioned Ball Parts and stretch them, but it isn’t easy.

I started doing the exact same thing as you trying to make aircraft components and that wasn’t going well. I saw that other people were making really good MeshParts using Blender or other 3D Mesh programs. I downloaded Blender and have been using it ever since. Just like making Unions, it’s a little daunting to learn, but there are so many tutorials or videos online that explain almost anything you want to do.

The other issue is that if you take a complex Roblox Union and export it to Blender you’ll see that it has so many more tris than an actual mesh requires.

For the complex shapes you require it’s going to be your best choice. You can also do a much better job of creating Textures that fit, rather than trying to get Decals to fit your Unions.

[Kollasi9]

Unions only create unnecessary tris if you use them incorrectly. You need to have all the vertices perfectly aligned, If you don’t have them aligned Roblox will create extra faces to connect them, thus increasing the tris. That’s why it’s better to use Blender, because it’s quite hard to get complex things aligned in studio, sometimes impossible, and you have full control in Blender.
Solid Modeling is not magical, it can’t guess what you’re trying to do.
For simple shapes, Unions are perfectly fine, they might even reduce the tris count depending on what you do and improve performance.

Use the wireframe rendering under the view tab to check the tris of unions.