IIW Bool (Alpha 4) IIW Bool is a texture that allows you to use one or more objects as cokie-cutters on other objects. Currently in Alpha testing, there is no support for shadows, but otherwise is fully functional. View an 880K Boolean Animation.

Table of contents: Overview Interface Instructions Common Problems and Solutions Examples and Ideas Download (Boolean Now!) Changes

This texture is a bit more complex than most, because it works together not with other textures on a single object, but on many objects in your scene. It takes a little extra setup to get it to work, but it is not difficult to use and once you get the hang of it you can quickly create objects and animations that would be difficult or tedious to perform without it.

There are four types of Boolean objects you can select.

Reset: Needed for the texture to work properly.
Additive: A nomal object that can be cut into.
Subtractive: Used as a cookie-cutter to cut holes in other objects.
And: Invisible unless two or more And objects intersect.
Colorize: Colors any parts of an object that intersects it.

RESET: The Reset object is very impotant if you want images without banding or other artifacts. The texture interface for Imagine is quite robust, but does have it's limitations. In this case, the problem is knowing when a new ray has been fired off by the camera. The texture has no way of knowing when to start it's calculations over for a new ray. Thus the need for a Reset object. This is an object that when a ray hits it, tells the Bool texture that it should stop keeping track of where in the scene it was, and start over. A Reset object will be completely invisible.

ADDITIVE: The Additive object is he next most important Boolean type. Applying this texture to an object lets Imagine know that it should cut parts out of it. This lets you accuratly specify what should or should not be affected by a Subtractive object.

SUBTRACTIVE: This is the main workhorse of this texture. Any part of an Additive or And object that intersects a Subtractive object will be chopped away.

AND: This lets you create effects not easily done with Additive and Subtractive objects. And objects are invisible unless two or more intersect. Using CSG spheres you can create new shapes by having several intersect in diffrent ways, or other interesting effects.

COLORIZE: Using this object you can colorize parts of an Additive or And object. You can add an Additive texture to the parent object of a spacecraft, and when making your laser object, make a bigger tube around it set to a molten-steel texture and as the laser passes through the ship, it appears to heat the surface. Used with a Subtractive object, you can appear to slice it in half too.

USE SUBTRACTIVE OBJECT PROPERTIES: Normally when rendering the internal faces of a sliced object, the Boolean texture will try and guess what color it should be based on the surface color of the Additive object when the ray passd through it. For solid colors it works fine, but it can give strange results when a complex texture is used instead. Use this checkbox to have the internal surface shaded with the cookie-cutters propeties. In the example, a red tube cut a hole in a blue sphere.

SHOW INTERNAL STRUCTURE: A normal transparent object (Left) will show objects inside it, as it renders every face. The Bool.itx texture treats objects as solids and by default will not show internal faces as they should not exist (Right). To show internal fases anyway, use this checkbox on each object you wish to be seen when it is inside another Boolean.

• Always use a Reset object between the object and the camera!
  Furthermore, if you are in trace mode and want Boolean objects to show up in reflections, you need to enclose the object in a Reset sphere as well or instead of one around the camera. If you are in the Detail editor, just make a large CSG sphere and set it to Reset to be able to Quickrender your objects.
• Make sure that objects are always closed!
  If there is a hole in an object so a ray only strikes it one, it will not look correct. The ray will 'escape' and act like the Boolean surface extends forever. This is not always a bad thing. You could create a flat plane, set it to And and any Anded objects in the scene would be invisible unless seen through the 'magic window' object. Further, you can set the window object transparent so if an Anded object gets between the camera and the plane, it still will not show up.
• Make sue you only have Bool.itx in ONE place!
  The Boolean texture needs to keep track of the ray status between objects, so it will not work if you have multiple Bool.itx files in your directory structure. This can happen if you have multiple texture directories to ease the loading of a friends objects, or if you place Bool.itx in it's prefeed location of Textures/Ian as well as in Textures and have objects that use both locations.
• Beware the crawling ants!
  The Boolean texture has the same problem that any surface does when two faces line up in the same plane. This can happen if you duplicate an object and don't move, rotate or scale it. To see the problem, create a default sphere, cut and paste it, and change the color of one object and render. With Boolean objects, the effects are even worse, so make sure to do small rotates if you have two objects that will line up one or more faces exactly.
  
• Crank up that Resolve Depth!
  Each face of a Reset, And, or Subtractive object that gets set transparent uses up one count on the Resolve Setting. You can quickly run into problems with low Resolve Depth settings, so if you begin seeing pure black sections then turn up the Resolve Depth. You can find it in the Options tab of the render window.
  
• I tried to use shadow casting lights!
  Don't DO that! You may have noticed that shadow casting lights do not work. This is a limitation with my texture that I am working on to correct. It may not be possible to solve, but I am still planning to release this texture as I have several emails stating it would be used dispite the restriction.
  

The above images show an example of the Bool texture. The first is without any textures applied. It is of a white tube intersecting a set of four 4x4 planes with Cube particles turned on and randomised face colors. The next image shows the center being Subtracted out, and the next shows the two objects Anded together. This object would not be easily made with Imagines standard tools, as you can't directly work with the faces of a particle object.

One thing I have found with this texture is that it seems to be better suited for special effects in animations than creating objects. Filling glass letters with water, various intersecting Anded object moving about.

Instructions: Click on what you want. :-)

• Download 12K: IIW Boolean Texture Zip (ALPHA 4 on Mar 14)
• Download 78K: Zip Archive of This Page (Mar 14)
• Download 880K: Boolean Animation. (AVI)

Alpha 1 (0.9.4) - A new boolean type called Colorize lets you color objects that fall inside it. Another (minor) speed increase. The interface has been recoded in C++ and file size has droped from 75K to 18K.

Alpha 2 (0.9.3) - New features include the removal of internal faces of solid objects, and the ability to turn off this feature. Minor speed increase. A few bugs fix.

Alpha 3 (0.9.2) - This is version two.. previous objects will have their Boolean Type wrong and will need to be fixed by going into texture properties and re-selecting the right one. Sorry about that, but it IS alpha and this should be the last time that backwards compatability will be sacrificed. The addition is a new type... AND. An and object alone will be invisible, and will only show up when two or more and objects intersect. Subtractive objects work on AND objects too, so you can punch holes and clip them just as you would a standard additive.

Alpha 4 (0.9) - Everything, inital release.

Last Update: Mar 14, 1998
©1998 Ian Smith (Send me Feedback!) Back to IIW Textures