It look like you're trying to define an animation system and a "kinematic solver", where you define some interactions between parts (ie gears, pistons, etc) and the whole system get in motion, or am i wrong?
As for brigl, it works by identifying "rigid groups" (your animation group, IIUC) with submodels. This way i didn't have to invent something new, and you can easily define the center of rotation of a submodel by placing it relatively to the origin (0,0,0).
I then tag animable submodels with the "ANIMATED" command which also gives a name to the group. Then at top level i define some animations, which are transformation on ANIMATED parts that can be chained, or in parallel, etc.
See an example here (mpd source)
This is a solution for animations only, i designed it to be able to show the "play feature" of my models. It doesn't deal with connectivity, mechanics, etc.
As i said, i used submodels to define a "tree" of subassemblies in relation with each other. This becouse the ldraw file format define a "flat list" of parts without the possibility to define a hierarchy. My solution of course have some problems, first of all it interferes with building instructions (BI submodels don't always coincide with Animation submodels).
If i'm not wrong, brigl animations looks similar to your "extension1", the difference being that in brigl animations are predefined, meant to be "started" with a button and watched, while your proposal define a range of possible movements and the user would be able to interact with them.
As for brigl, it works by identifying "rigid groups" (your animation group, IIUC) with submodels. This way i didn't have to invent something new, and you can easily define the center of rotation of a submodel by placing it relatively to the origin (0,0,0).
I then tag animable submodels with the "ANIMATED" command which also gives a name to the group. Then at top level i define some animations, which are transformation on ANIMATED parts that can be chained, or in parallel, etc.
See an example here (mpd source)
This is a solution for animations only, i designed it to be able to show the "play feature" of my models. It doesn't deal with connectivity, mechanics, etc.
As i said, i used submodels to define a "tree" of subassemblies in relation with each other. This becouse the ldraw file format define a "flat list" of parts without the possibility to define a hierarchy. My solution of course have some problems, first of all it interferes with building instructions (BI submodels don't always coincide with Animation submodels).
If i'm not wrong, brigl animations looks similar to your "extension1", the difference being that in brigl animations are predefined, meant to be "started" with a button and watched, while your proposal define a range of possible movements and the user would be able to interact with them.