This week’s topic is how we can use two different solvers in conjunction with each other.

Usually in rigid body simulations you want a solid object to shatter as a result of some kind of impact or force. For example, you might want an earthquake to destroy a house, causing concrete walls to break, wooden doors to shatter and glass windows to break. Or, you might want a swinging demolition crane ball to make a hole in a wall.

Most of the fragmentation tools in Houdini support a pre-fracture workflow, where you can break the geometry into pieces in SOP and hold these pieces together with glue constraints. Pre-crushing gives you complete artistic control over the appearance of the damage (for example, whether you want large fragments or small jagged pieces). Objects collapse when a force exceeds the strength of the glue, or you can manually animate the glue when you want the object to collapse. If you need more control over fracture, there are many lower level SOPs.
Simulates fracture patterns associated with different materials: concrete, wood and glass.
If you just want a bunch of fragments to stick together permanently, give them all the name attributes. The nodes that work on the fragments will treat them as one fragment at a time. This can be useful, for example, in wood splitting, where you often want to combine small fragments into larger jagged chunks.
For certain effects that can be broken straight away, you will often want to process larger pieces early in the shot and have them break up into smaller pieces later in the shot. You can do this with a level of glue constraint. You can animate higher level constraints to break up larger pieces into smaller pieces.
The RBD material breakage node provides clustering control when the material type is ‘wood’. You can use the RBD clustering node for manual clustering.