All right, welcome back everyone. In this video we are going to talk a little bit more about additive and subtractive brushes in Unreal Engine four and seeing how they work. So again, as we just covered over in the Modes panel, which is way up here in the left hand corner of our editor, we are by default in place mode. along the left hand side, you've got various tabs and we are going to be selecting this geometry tab. And with that selected, you have access to various geometric brushes to drag and drop into your level and it's as simple as left clicking and dragging this out into your level like so. Now this is an additive brush, because it added geometry to our world.

It added this cue shape and I know that it's an additive brush not only because I see that it added geometry but because with this act selected, this is known as an actor. Now that's added to my level. Over in the Details panel, it says the brush type is additive. You can also see that anytime we add any of these particular geometric shapes to our level, the down here it is determining if what we are adding is an additive brush or a subtractive brush. So I could change my next box brush that I'm about to bring in here to be subtractive right out of the gate. So let me click on this to change that to subtractive.

And now I'm going to left click and bring in a subtractive box brush. Now it's gonna show up in this kind of wireframe II view. And if I move this over to the left to intersect with my additive brush, you will notice that it that it takes away geometry from the additive brush. Now I'm gonna damage straits something that may confuse people right out of the gates. But I'll explain what's going on in just a moment here, I'm gonna bring out another box brush. And again, it'll be subtractive by default, because I've got subtractive selected down here.

And I can change this brush to be additive from over in the Details panel. So changing it from subtractive to additive. Now, you might think that if I move this additive brush over to where my subtractive brush was that that subtractive brush would take away from it. But you can see that while the subtractive brush takes away from this one, it doesn't take away from this one. One thing I just want to point out really quickly though, subtractive brushes can be a little tricky to select After you select it off of them. So if you were to click on the inside portion of this additive brush right about here, that's an easy way to get that subtractive brush back so you can see That our subtractive brush here is overlapping this other additive brush, but it's not taking away from it.

That's because the ordering of when we place these actors is not conducive to subtracting from this one. Because you see this box brush was the last thing that we added to our level. If I was to take this subtractive brush, and over in the Details panel I go under the brush settings and I click this Show Advanced. There is an order option and I can click on this and set this to be the last thing that I have placed in the level. And now you'll see that it does in fact subtract from this geometry. So if you're ever wondering why it is not subtracting or adding like you are expecting, just remember that in our brush settings where there's this little drop down arrow to show advanced, you can change the order with which your various brushes were added to your level.

Okay, with that all done, what I'm going to do is I'm going to delete out this guy, and I'm going to demonstrate for you very quickly how you could make a door and a window setup. So I'm just gonna take my additive brush here, I'm gonna scale it like so, maybe make a wall like this. And I'm gonna move it over and up and tap that end key to make a drop down to the floor. You can see my subtractive brushes right there. So making a window would be nothing more than making sure that your subtractive brush penetrates all the way through an additive brush like so. So you can imagine how you can create windows and doors just like that.

Anyways, that is all I'm going to demonstrate here in terms of additive and subtract interactive brushes. Just as a quick recap, here's our geometry tab with various geometric shapes. We focus here on the additive and subtractive brushes, you can change their additive or subtractive right when you place them into the level by clicking either of these. And once they are in your level, you can come under the Details panel with that brush selected and change if that brush type is additive or subtractive. And if you're not happy with how the additive and subtractive brushes are interacting with one another, don't forget this advanced menu where you can change a given brush to be first or last. That is gonna do it all for this one guys.

We will see you in the next one.