Most (not all) of the commercial game engines I've worked with use collion shapes (solids) and visual shapes which are distinct from each other.

For environmental objects the Conitec engine seems to favor a constructive geometry approach where the environment is build out of primitives which are used for both the visual and the collision database.

Does anyone know if there is a performance penalty associated with constructing collision solids out of primitives and making them invisible and overlaying entities which supply the visuals, but which are non-collidable? In addition to being a more familiar way to work this approach would allow me to make the visual shapes more complex and LOD appropriately without requiring more complex collision solids.

As a new user (though an experienced real-time technical artist) I'd be curious about any other comments on the merits and shortcomings of these two approaches.

Thanks

You can do this quite easily if you would like - the only thing that would be of concern is the additional faces which would need to be drawn in order to realize it. Even if you where to make the level geometry invisible, the engine would still need to determine where it is in relation to the character in order to allow for proper collision detection. So basically, you take a hit in your overall scene budget for both the visible and invisible faces in this situation.

There are also other considerations in regards to the way shadows and lights interact with CSG geometry in A6, in comparrison to how they interact with normal mesh objects.

Depending on your timeline you might not have to worry too much though - they are planning on moving away from the current method in the future (near or far is unknown as of yet). Unfortunately it is a "loose" schedule, so it would be hard for anyone but JCL to say if it is 3 or 6 months away or even more.

My experiance in this area has been a performance increase.
Make your sprite passable and your home free.
But, there could be penalties with an oversaturation of sprites if one goes overboard on quantity, size and with respect to portal counts. See here

Yes Dan, thats why I said "and" so I guess my typo was overlooked.
The 'look here' should have cleared that up though.
Will try to watch my typing in future but no promises.