Advanced Boolean Operations
So you've created an object that you want to perform complex boolean operations on and it's not working. First you may want to read the Basic Boolean Tutorial. Then after you read that, this tutorial will help you learn why it's not and how to make it work.
First we will create an object, then we will break it apart with boolean operations. So lets create a the column’s body then give it a little character.
Column Body (top and side views).
Create a cylinder then change its position to coordinates 0, 0, 0 by selecting the "A" for attributes. I harp a lot about moving your objects to those coordinates. It simply makes it easier to know what’s going on with the object you are modeling by providing a reference for you.
Next resize the cylinder, for this example just use the size indicated.
Next set the cylinder’s attribute to make it positive. Also set it so that you can see the origin handle because we are going to play with the origin of the object for a quick way to make the column’s body.
You must set an object to either positive or negative. Bryce defaults to creating an object to neutral (in Windows) and if you do not change this, your boolean will not work. Let me say that again, every object (including primitives or groups) in the group that you want to perform the boolean on MUST be either positive or negative. NO NEUTRALS!
I want the column body to be about 24 inches across and I have decided that one Bryce unit will equal 1 inch. So since I want the column body to be 24 inches I have set the origin of the cylinder to be 1/2 the size of the desired column body size (1/2 of 24 = 12). This value can be either positive or negative depending on what mood your in.
Click the lock. This will make it possible for the origin and position to be different locations when typing here.
Duplicate the cylinder and rotate the new cylinder. Notice that it rotates around the new origin point. (picture shows top view)
Next replicate the cylinder.
You could MultiReplicate, but you aren’t really sure how many it will take to make the whole column body. You could mathematically figure it out but this will suffice for this example.
Keep replicating until you have the column body like the one shown (top view).
Now that you know how to use the origin and how to replicate objects, create some detail for your column. Here I created a sphere and did the same steps as above.
Don’t forget to make the spheres positive!
Create a base and add a little more detail. I used cube and torus primitives for the detail. Group the entire column here and make it positive.
Be sure to make them positive! Remember if you make any groups for faster replication of detail, that group must also be set to positive! For instance I grouped the first sphere applicants. Then I made that group positive. Then all I had to do was duplicate the group and reposition and resize to suit my taste.
Now I want to break my object up to give it some character. So I created a cube and a terrain. I made these both positive. Then I grouped the two and made that group NEGATIVE.
Now reposition the negative terrain/cube group over the positive column group. Group these two objects. If you didn’t forget to make something positive or negative, you will have successfully created an advanced boolean operation.
You can create some variation by duplicating the model and repositioning, rotating and/or resizing your negative group for a little variety.
What did you learn here? I certainly hope you know now that there can be NO neutral objects in your boolean group. If there are, you will not get a boolean, or it will not work properly. If you manage to perform the operation and have a neutral object in the group, consider yourself lucky. Just get in the habit of either positive or negative for boolean groups. It could save you tons of headaches later if you decide to change something or want several different variations of your model.
In two words "Plan ahead".
The building in the background of the image above was actually broken in two pieces in the image at the top of the tutorial. So you can perform this operation with any size of object group. Imagine if I’d forgotten to change one the objects in it to positive? Talk about a headache to re-render a picture. The final image took 6 hours on a 500 MHz/384 RAM computer. It would have taken days on my 133mhz