I'm sure I'm becoming a nuissance on these boards....

:stuck_out_tongue:

Yes I am running into more trouble. Please do not link me to any tutorials because I have several bookmarked and another very detailed guide DLed to my harddrive.

I am having trouble with boolean operations. The guide says to use Boolean Difference to make a hollow object. I made one large cube. I then made a slightly smaller one and put it behind the orginal, bigger cube. I then selected both in object mode and hit the w key. I then proceeded to click Difference in the menu that popped up. However, I didn’t see any changes. After that I tried to make a window using the same process but it didn’t work. Am I doing something wrong?

make sure you have selected them in the right order, and other than that, you seem to be doing it right.

Yes, I think actually you are. if I understand you, the smaller cube is completely inside the bigger cube, right?

Since the two objects you selected do not have any intersecting faces, no boolean operation is possible on them.

Blender is a polygonal modeller, and as such used vertices and faces. It would be different if it was a solids modeller.

Try this, move the smaller cube so that it’s center is on one of the faces of the bigger cube, like this:



 ____________
|            |
|         _________
|         |       |
|         |       |
|         |       |
|         |_______|
|____________|


Then try the boolean operation.

BTW, booleans do not work perfect in blender as of yet. You can do a serch here for a script that works better.

EDIT: Sorry, this is one more thing which may be the “problem”. When you do a boolean operation, it make a copy of your objects. So try moving the cubes after you do the boolean.

And my ascii diagram doesn’t look the same as it did in the edit box. Hmmm.

I find that boolean operations usually give me far more faces than I wanted to begin with, and they muck-up the entire model, so I avoid them completely. It’s easier (imho) to do it by hand. And you get a cleaner result.

If you’re familiar with scan-fill (flood-fill) operations, that’s the basic difference between inside and outside. Outside is what you see (from the camera) and inside is what you can’t. (The trick, of course, is to not move the camera inside…)

There’s nothing wrong with asking questions. Better titles than “I need help” are a good idea though (like “boolean ops are confusing me” or somesuch).

Yes, I think actually you are. if I understand you, the smaller cube is completely inside the bigger cube, right?

Since the two objects you selected do not have any intersecting faces, no boolean operation is possible on them.

Blender is a polygonal modeller, and as such used vertices and faces. It would be different if it was a solids modeller.

Try this, move the smaller cube so that it’s center is on one of the faces of the bigger cube, like this:



 ____________
|            |
|         _________
|         |       |
|         |       |
|         |       |
|         |_______|
|____________|


Then try the boolean operation.

BTW, booleans do not work perfect in blender as of yet. You can do a serch here for a script that works better.

EDIT: Sorry, this is one more thing which may be the “problem”. When you do a boolean operation, it make a copy of your objects. So try moving the cubes after you do the boolean.

And my ascii diagram doesn’t look the same as it did in the edit box. Hmmm.[/quote]

Hmmm… didn’t seem to work. Now I have half a cube stickin out of my house’s wall. :stuck_out_tongue:

Sorry, I’m a complete n00b and am not famiiar with scan-fill operations.

But did you move the cubes around after too?

Like I said, boolean makes a copy of the objects, so your origional objects will still be there. If they are, you won’t see the new object.

Yes, I moved them around, and yes, there were two identical shapes. Do I delete one of the copies?

Scan-fill works like this. Say you have a geometric figure:

  +------+
x |      |
y | +--+ |
  | |  | |
  +-+  +-+

And you want to know what’s inside and what’s outside.

Suppose we start at x. We start outside. Moving right, we hit a wall. Now we’re inside. Keep moving right. We hit another wall, so now we’re outside. There’s no more walls to hit so we’re done.

Suppose we start at y. Moving right, we hit a wall. Now we’re inside again. Moving right, we hit another wall. Outside again. etc.

That’s the way things work in 3D. The difference between ‘inside’ and ‘outside’ is a matter of where you put your x’s and y’s (i.e. your camera).

Anyway, my whole point was that you usually get a better result by joining the two objects you plan to do your boolean operations with then deleting the vertices you don’t want and manually connecting them where you want them to be connected.

Hmmm… makes sense to me. I’ll start toying around a bit with the camera. Normally I don’t adjust the camera much at all.

Seriously, though, if you even use the boolean command, a new object is made. Your two other objects are left intact, while a new object is made. I suggest that you at least look at the new object each time. If it isn’t right, then try selecting the objects in a different way and run the boolean operation again.

Good luck,
–lir

Thanks, I’ll give it another go!

You have a misconsception. The cube is already hollow, there is no way to cut a hole in a hole ;_)

You have a misconsception. The cube is already hollow, there is no way to cut a hole in a hole ;_)[/quote]

Huh? Last time I checked, a cube is a solid… :expressionless:

That’s the whole point. It’s not solid. It’s a collection of 8 vertices connecting 6 faces. “Solid” and “hollow” mean nothing. There’s nothing there but the faces and vertices.

So if you were to cut the cube in half, it’d be like cutting a cardboard box in half. There’s nothing there but the sides of the box.

That was also the point behind the scan-line thing. If you want the cube to be “solid” after you’ve cut it in half, you have to add the face that’s missing. You’d get the same result if you’d just grabed four of the vertices and moved them closer to the other side.

The only difference between “solid” and “hollow”, etc., are how it is perceived. If, when you look at the picture of, say, an apple with a bite out of it, we perceive it as “solid” because that’s how apples are in real life. But in the computer, there’s nothing underneath what you see. The apple and the bite are both just a collection of vertices connected by faces. It’s a magic trick – a visual sleight of hand.

Boolean operations take two meshes and try to mimic the “solid” concept, but they’re really just manipulating which faces to keep and which faces to throw away between the two objects.

I hope this makes better sense…

That’s the whole point. It’s not solid. It’s a collection of 8 vertices connecting 6 faces. “Solid” and “hollow” mean nothing. There’s nothing there but the faces and vertices.

So if you were to cut the cube in half, it’d be like cutting a cardboard box in half. There’s nothing there but the sides of the box.

That was also the point behind the scan-line thing. If you want the cube to be “solid” after you’ve cut it in half, you have to add the face that’s missing. You’d get the same result if you’d just grabed four of the vertices and moved them closer to the other side.

The only difference between “solid” and “hollow”, etc., are how it is perceived. If, when you look at the picture of, say, an apple with a bite out of it, we perceive it as “solid” because that’s how apples are in real life. But in the computer, there’s nothing underneath what you see. The apple and the bite are both just a collection of vertices connected by faces. It’s a magic trick – a visual sleight of hand.

Boolean operations take two meshes and try to mimic the “solid” concept, but they’re really just manipulating which faces to keep and which faces to throw away between the two objects.

I hope this makes better sense…[/quote]

Actually, it makes a lot more sense now. Thanks a lot Duoas!