DOP Rigid Body Simulation

DOP theory

  • w attribute = angular velocity
  • understand the dop object as container, which can contain thousands of rigid body packed fragments (or packed geometries)
  • pack name – “piece”
  • pack fragments vs packed geometries – packed fragments stored in one memory location and fragment is sublocation
  • the Bullet solver automatically detects objects that are initially overlapping and prevents them from colliding/exploding until they separate (since H12.5)
  • passive objects can be collided with by active objects, but don’t move, and are not affected by forces
  • walls/floors, raying a grid to get the shape and then extruding the faces into unconnected little cubes speeds up collisions

Fractured Rigids SOP

Pack SOP
  • no materials until unpack
  • orientation etc. stored in Primitive Intrinsics
  • fast view as Point Cloud
  • path: op:`opfullpath(‘.’)`
Connectivity SOP
  • attribs from polygon connectivity
Partition SOP
  • groups from rule
  • group_$CLASS (@class being prim attrib created by connectivity SOP)
Exploded view SOP
  • poly connectivity from attribs
Packed Edit SOP
  • can change visibility etc
Name SOP
  • name from group
Voronoi SOP
  • poly connectivity from VDB/scatter
Voronoi Fracture Points SOP
  • adds points to surface/interior depending on position of Impact point
Assemble SOP
  • finds connected islands of geometry
  • gives name to pieces
  • packs into Packed Fragments (not packed geometries)

Fractured Rigids DOP

RBD Packed Object DOP
  • use SOP path
  • Geometry Representation (Convex Concave etc)
  • BULLET is made for Convex, Concave is slow with thousands of pieces
  • Collision Compound
    • VDB to spheres, Bake ODE, Merge
  • use Collision Padding (0 = same as geo, 0.1 = far from)
RBD Object DOP
  • same as above
  • use SOP path
RBD Point Object
  • creates a new simulation object at each point of a source geometry object
  • useful for simulating a large collection of identical objects
Static Object
  • its motion is not controlled by the simulation
Rigid Body Solver DOP
  • solver types
  • RBD was built in solver, not used much anymore
  • ODE never use
  • Fracture – we don’t use
Merge DOP
  • defines collision
 POP forces
  • can be used to drive rigid body simulation (packed as points)
  • wire node into Post-solve or Pre-solve
Gravity DOP
  • does not create force attribute on point
  • creates “../Forces/Gravity”