[Steve]

John:

I think it is important to point out that OneSpace Modeling does provide the option of adding some design intent or more "intelligence" to 3D models. You do not have to define your design intent, but you can.

The optional Parametrics module can be used to define relationships between elements (faces, edges, etc.) within a part. For example you can specify that a hole should be a certain distance from a face and that relationship will be maintained as you modify the part. You can move the hole relative to the face by editing the relation.

The parametrics module in OneSpace Designer is so weak that you are limited in the parameters you can apply. The tapered cylinder example is a classic, trivial example of the shortcoming. If you have relatively primitive geometry, with lots of planar faces and edges for applying parameters to, then you may have some success with them. But if your parts are drafted and radiused, the theoretical intersections you would like to dimension to don't exist as far as the modeler is concerned, and you can't apply parameters to control them.

Not only this, but the parametrics in OSD are pretty much an all-or-nothing proposition. Unlike feature-based modelers, where you can simply click on a feature and the relevant parameters will light up on-demand, with OSD they are always visible. Yes, there is a browser window you can use to turn off and on individual parameters but unless you have given meaningful descriptions to each parameter it is difficult to tell in the browser which parameters go with which feature(s) on the model.

I found the parametrics so cumbersome to use that I, a parametric freak, gave up using them in OSD.

Ron:

I find it very interesting that these folks, with their background and understanding of history and parametrics based MCAD system, chose to create essentiallly another "dynamic modeling" MCAD system.

I'm not surprised at all, especially after watching their webcast debut. Basically their market studies have indicated that 4/5 of potential CAD users can't figure out how to use embedded logic in 3D models. So they are going after that segment of the market with a less sophisticated, easier to understand CAD tool. There's no doubt or argument that Boolean CAD tools are simpler to use than parametric ones. It's a question of power. My guess is that companies like CoCreate and SpaceClaim have found that the power-user market segment is effectively saturated. So they're going after the users who don't presently want, need, or understand how to embed logic into their designs. Unfortunately, eventually you reach the point where you do want to embed logic into your design, just like they did back in, oh, 1992 or so, and you find the limitation of Boolean CAD software.

Steve