- [Instructor] 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.
And 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 courtyard walls 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 courtyard wall.
Okay, let's investigate that wall.
I'll select it.
Go to the modifier panel
and we've revealed 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've disabled 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 two splines nested inside a third one.
So, I'll exit out of spline cell object mode
and re-enable the extrude modifier,
reselect 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 view port 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 zero meters, press tab
and set the Y position to 10.5 meters and press enter.
We'll leave the Z at zero 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 modifier panel and we going to 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.
And we going to 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 modifier 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 send it to a light pink and click okay.
And orbit around,
once again, that 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 render not knowing
which of these polygons is in front and which is behind.
And 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 it's 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, okay?
Our scene is set up for creating a boolean compound object.
We'll take a look at that in the following movie.