From the course: 3ds Max 2024 Essential Training

Preparing Boolean operands - 3ds Max Tutorial

From the course: 3ds Max 2024 Essential Training

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Preparing Boolean operands

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To begin the chapter on polygon modeling, let's start with booleans. That is a technique for combining objects. We can add, subtract, or find the intersection, which is the overlap, among the volumes of various objects. Those objects are called operands within a boolean compound object. We'll use the boolean compound object to create holes for doors and windows here in these walls. I've got a CourtyardWalls object and I've got a bunch of boxes. And those boxes are going to be holes. We're going to cut those volumes out of the CourtyardWall. OK, let's investigate that wall. I'll select it, go to the Modify panel, and we reveal that it started its life as an editable spline. And then it got extruded with an extrude modifier. We can disable the extrude modifier just for a moment. To the left of the name of each modifier, you'll see an eye icon. That allows you to enable or disable that modifier. So click that eye or visibility icon and we disable the extrude modifier. Let's go into the editable spline sub-object modes. We'll select spline sub-object and investigate the structure here. We've got three sub-splines within this spline. There's an outer spline, and that's the sort of exterior or outer surface of the wall. There's a nested spline inside that, and that's the interior surface of the wall. And there's a third spline, and that's the interior surface of this other area, which is for a hot tub. So we've got a semi-complicated setup here in which there are two splines nested inside a third one. So I'll exit out of spline sub-object mode and re-enable the extrude modifier, re-select it to go back to the top of the stack. So this is an extruded spline with a semi-complicated structure and that's probably just fine for a boolean operation. But I do recommend, just to be safe, you should usually convert a complex object to editable poly before adding it as a boolean operand. So I'll do that and it'll help to avoid any potential issues with the boolean. Sometimes you can get some strange results. So let's convert to editable poly. We'll go over to any viewport and right click in that view and from the quad menu choose convert to, convert to editable poly. Now it's no longer a spline with an extrusion, it's a raw editable poly object. Now again I've created all of these boxes and those are going to be subtractors for portals for doors and windows. I also need a box in order to subtract an area over here in the north wall for an arch. So we'll create one more box, go to the Create panel, click Box, click and drag in the perspective view to set the footprint of the box, release the mouse, and drag upward to set the height, click to complete that box, and then right click to exit the tool. I want to move it into position here on that north wall. Grab the Move tool and set the X position here in the Transform Type-in area. Set that to 0 meters. Press Tab and set the Y position to 10.5 meters and press Enter. We'll leave the Z at 0 for now. So the box is in position. We want to change its dimensions to make it the right size. With it still selected, go to the Modify panel. And we can adjust the length. Click and drag on that spinner and reduce that. We don't need much for this length. That's the thickness of the box. It only needs to be just thick enough in order to penetrate both sides of the wall here. So let's give it a length of one meter, and that's plenty. For the width, we'll set it to two meters. Press Tab and set the height to 2.5 meters and press Enter. And now it's more or less in the right position. Let's go back to our perspective view, right click in that view so we don't lose our selection, and zoom in with the Z key on the keyboard. We can orbit with Alt and middle mouse, and it looks okay to the naked eye, but actually if we tried to boolean this we would have a problem. And it's because the polygon at the bottom of the wall is exactly coincident with the polygon at the bottom of the box. And if we orbit around with Alt and middle mouse, we can maybe see some flickering. That's called z-fighting. We can make that more obvious by changing the color of one or more of the objects. I'll select the walls courtyard object. And in the Modify panel at the top, we have the name, but we also have a color swatch. That's the color of the object. Click on that color swatch and set it to a light pink and click OK. And orbit around, once again, the perspective view. Select the box object and orbit around. And you can kind of see the flickering or z-fighting. So that's the viewport renderer not knowing which of these polygons is in front and which is behind. That'll also be a problem for the Boolean compound object. And it might have an issue where we have one polygon right here at the threshold. And that'll be a real problem. It'll be hard for us to get rid of that. So to avoid the problem happening in the first place we can just move this box down slightly so that its volume completely penetrates the bottom of the wall. So with that box selected we can give it a Z position of negative 0.25 meters and press Enter. And now we've moved it down just enough so that we won't have an issue because that box is now penetrating the bottom of the wall. We won't get any extra polygons at the bottom because we've created some overlap there. OK, our scene is set up for creating a Boolean compound object. We'll take a look at that in the following movie.

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