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Creating Boolean Objects
A Boolean object is an object created by combining two or more objects to form a single object. Boolean objects are created by performing Boolean operations on a number of objects. You can perform three types of Boolean operations in Bryce: union, subtraction, and intersection.
Bryce uses Object properties to perform Boolean operations. Objects can be Neutral, Positive, Negative, or Intersecting. When you combine these objects in a group, the result is a Boolean object.
Boolean operations do not have any effect on Neutral objects. When you group a neutral object with a Boolean object, no Boolean operation is performed.
If you were to group a neutral object with a Boolean object, both objects would remain visible, as no Boolean operation occurs.
Objects are neutral by default.
If you are importing objects from Bryce 2, you may want to change some positive objects to neutral for faster rendering.
Boolean Operations
Boolean Union is performed by grouping two positive objects. The area that is common to both objects is removed, creating a continuous object. For example, when you group two positive spheres, you get a kind of peanut shaped object which is the union of the two objects.
Boolean Union is performed by grouping two positive objects.
Boolean Subtraction is performed by grouping a negative object with a positive object. The area that is common to both objects is subtracted from the positive object, resulting in a positive object with negative space. For example, when you group a positive sphere with a negative one, the resulting object looks like a sphere with a crater.
Boolean Subtraction is performed by grouping a positive object with a negative object.
Boolean Intersection is performed by combining an Intersecting object with a Positive object. The area that is common to both objects becomes the only visible portion of the group.
Boolean Intersection is performed by grouping a Positive object with an Intersecting object.
Negative or Intersecting objects must share space with at least one Positive object in the group to exhibit a Boolean operation. If there is no common space, Negative objects are invisible when rendered.
A group that contains an Intersecting object that does not intersect with any other object in the group becomes entirely invisible; this is because the Intersecting object is intersecting with nothing.
You can build very complex objects by compounding Booleans. Suppose you wanted to create a flute. You would first create the hollow tube by combining a positive cylinder with a negative cylinder, then create several negative spheres and group those with the tube, creating a simple flute.
This simple flute was created by grouping a hollow tube with several negative spheres.
By compounding more Boolean operations on top of this simple flute, you could create even more complex objects.
Since Bryce performs Boolean operations using object attributes, you can adjust the shape of a Boolean object by repositioning the objects in the group. You can edit objects within groups using the Solo mode in the Selection palette. Refer to "Selecting Objects" for more information.
The final Boolean object appears only in the rendered image or in the Nano-Preview. You won't be able to see the Boolean object in the Wireframe preview.
To subtract one object from another:
2 Click the A button next to the object's bounding box, or press Command-Option-E/Ctrl+Alt+E, or choose Objects menu> Edit Attributes.
The Object Attributes dialog appears.
3 Enable the Negative checkbox.
4 Move the negative object so that it intersects another object.
5 Make sure that the second object's Boolean attribute is set to Positive.
6 Select both objects and click the G button next to the selection's bounding box to group them.
When your scene is rendered, the area where the two objects intersect is removed from the positive object.
To create an object that is the intersection of two objects:
2 Click the A button next to the object's bounding box, or press Command-Option-E/Ctrl+Alt+E, or choose Objects menu> Edit Attributes.
The Object Attributes dialog appears.
3 Enable the Intersecting checkbox.
4 Move the intersecting object so that it intersects another object.
5 Make sure that the second object's Boolean attribute is set to Positive.
6 Select both objects and click the G button next to the selection's bounding box.
When your scene is rendered, the area where the two objects intersect becomes the only visible portion of the group.
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