Antoine Clappier Date: Tue Mar 7, 2000 4:19pm Subject: Booleans Dear Dreamers, Boolean operations are known to be developer nightmare. Even if this feature appears to be simple, it is in fact extremely complex because you can substract any kind of object to any other. It is always a good idea to avoid boolean operations when possible (and not only in Carrara, it is also true in 3DS MAX and most of the 3D products!). Carrara's spline modeler and vertex modelers can generate most of the objects you will need without using booleans. Here is a classical example: Let say you want to carve a text in a board: You can create a cube, the text with the text modeler then substract the text to the cube. This is not a good idea: you can not change your text anymore, the number of facettes will be fixed (can generate problem when zooming on object), you can not resize the board without distorting the text, the UV Mapping will be destroyed. An other way is: In spline modeler create the text, convert text to outlines, draw a rectangle, then group all as a compound. By doing this, the object can be later fully edited, UV mapping is perfect, number of facettes can be changed, the object is much smaller to save and easier to manipulate by Carrara. Why you should avoid booleans in Carrara and other products ? First reason: booleans generate too many facettes. The booleans are a set of algorithms that can not replace the human. Second reason: boolean objects are not optimized for rendering. The number of facettes is fixed and cannot be optimized on the fly to generate smoother renderings or accelerate rendering. Third reason: Booleans can fail. There is an infinite array of possibilities when combining 3D objects. It is nearly impossible to have an algorithm that can handle every single possibility. Fourth reason: UV Mapping will be lost (in most case). If you absolutely need to do a boolean operation, here are advices: - avoid to do boolean operations with very detailed objects (details will be lost anyway). - avoid to apply booleans to completely different objects (a cube and a text is the worse case: the cube has 12 facettes, the text can have thousands of facettes). - when combining completely different objects, try to increase or decrease the number of facettes of one of the object (in the previous example, edit the cube in the vertex modeler to increase the number of facettes). - use vertex modeler to re-generate fake UV mapping or use an external tool. - save a copy of the objects used during the boolean operation (if later, you need to modify the object, you will be glad to use the saved objects instead of recreating everything from scratch). Happy rendering to all, Antoine Clappier - MetaCreations Senior Manager, 3D Technologies