Bullet constraints network questions

[catchyid]

Hi, 

some basic questions on constraints network  any feedback is appreciated ! BTW, I am using bullet solver

a) what's the main difference between glue constraint and hard constraint? they seem doing the same job for me?

2) on a sop level, primitive, one can set s@constraint_type="all|position|rotation", however in a dop level, we still need to create a constraint specifically by type, i.e. glue or spring, etc ==> why have this redundancy? we have the constraint type twice?

thanks

[Andrea]

2) Glue, hard, spring and cone are different type of constraints with different behaviours and attributes that you can use for get the desired result. For example spring constraints can stretch, glue constraints can't. 

"All,position, rotation" has nothing to do with this but specifies if the constraints are allowed to rotate or change the relative position between the extremities. In the example files of Houdini there are some great scenes where you can easily see the difference between them. 

 

1)  Said this... It's true that if you don't allow the change of rotation/position (constraint_type->all) on hard constraints they are almost as unbreakable glue constraints. But keep in mind that glue constraints can just be broken or not. With hard constraints you can do much more.

For example with hard constraints you can specify the exact direction that they are allowed to move, how much they have to move or rotate before breaking and so on. 

[catchyid]

Thanks Andrea, I'll look at the example files I guess, it's always good to test them  Once more, thaaaanks