Bullet Solver CHOP
The Bullet Solver CHOP is used in conjunction with a Bullet Dynamics system. It outputs the solved results from a Bullet simulation and can include the results for the entire system (Bullet Solver COMP) or an individual actor (Actor COMP) within a system.
The Bullet Solver CHOP can also be used with the "Feedback CHOP" parameter on the Bullet Solver COMP or Actor COMP. Bullet Solver simulation results can be grabbed using the Bullet Solver CHOP, modified, then fed back into the Bullet Solver COMP it came from. The values at the beginning of the next step of the simulation will be whatever values are in the CHOP that is fed back. This allows any CHOP data to be injected into the simulation at the beginning of the next frame (time step).
For example: making an actor in the simulation jump to the mouse cursor when clicked.
- actor_id: the OP id of the Actor COMP
- body_id: the id of the body within the Actor COMP. Actor COMPs can have multiple bodies if they are static or if instancing (see: Actor COMP). Body id's increment from 0 to N-1, where N is the total number of bodies in an Actor COMP.
- active: whether the body is active in the simulation
- colliding: whether the body is currently colliding with another body
- colliding_actor_id the ID of the Actor COMP that contains the body we are colliding with
- colliding_body_id the ID of the body we are colliding with; together with colliding_actor_id will map back to a specific body in the simulation
- total_collisions: the total number of collisions this body has had
- t[xyz]: the translation of the body in the given transform space
- r[xyz]: the rotation of the body in the given transform space
- s[xyz]: the scale of the body in the given transform space
- vel_t[xyz]: linear velocity of the body
- vel_r[xyz]: angular velocity of the body
Parameters - General Page
Solver or Actor COMP
comp - A reference to either a Bullet Solver COMP or Actor COMP. If a Bullet Solver COMP is referenced then the CHOP will output the simulation results for all of its actors. If an Actor COMP is referenced then the CHOP will output the simulation results for only that actor.
xformspace - ⊞ - The space in which to output the transformation values. That is, the transform values (translation/rotation) will be outputted relative to the selected space.
world- The output transform is in the world coordinate system.
- Bullet Solver
bulletsolver- The transform output is relative to the Bullet Solver COMP.
actor- The output transform is relative to the Actor COMP.
collisioninfo - Adds colliding, colliding_actor_id, colliding_body_id, and total_collisions channels to the CHOP. In order to track these values for a body, "Perform Contact Test" must be enabled on the Bullet Solver COMP.
trans - Adds translation channels to the CHOP.
rot - Adds rotation channels to the CHOP.
scale - Adds scale channels to the CHOP.
linvel - Adds linear velocity channels to the CHOP.
angvel - Adds angular velocity channels to the CHOP.
rate - The sample rate of the CHOP.
Parameters - Common Page
timeslice - Turning this on forces the channels to be "Time Sliced". A Time Slice is the time between the last cook frame and the current cook frame.
scope - To determine which channels get affected, some CHOPs use a Scope string on the Common page.
Sample Rate Match
srselect - ⊞ - Handle cases where multiple input CHOPs' sample rates are different. When Resampling occurs, the curves are interpolated according to the Interpolation Method Option, or "Linear" if the Interpolate Options are not available.
- Resample At First Input's Rate
first- Use rate of first input to resample others.
- Resample At Maximum Rate
max- Resample to the highest sample rate.
- Resample At Minimum Rate
min- Resample to the lowest sample rate.
- Error If Rates Differ
err- Doesn't accept conflicting sample rates.
exportmethod - ⊞ - This will determine how to connect the CHOP channel to the parameter. Refer to the Export article for more information.
- DAT Table by Index
datindex- Uses the docked DAT table and references the channel via the index of the channel in the CHOP.
- DAT Table by Name
datname- Uses the docked DAT table and references the channel via the name of the channel in the CHOP.
- Channel Name is Path:Parameter
autoname- The channel is the full destination of where to export to, such has
autoexportroot - This path points to the root node where all of the paths that exporting by Channel Name is Path:Parameter are relative to.
exporttable - The DAT used to hold the export information when using the DAT Table Export Methods (See above).
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samples-per-second of a CHOP. Each CHOP in your network has a sample rate, whether it is used or not. The overall timeline has a "frame rate", which is the number of animation frames per second, generally your monitor display frequency.
A Time Slice is the time from the last cook frame to the current cook frame. In CHOPs it is the set of short channels that only contain the CHOP channels' samples between the last and the current cook frame.
A parameter in most CHOPs that restricts which channels of that CHOP will be affected. Normally all channels of a CHOP are affected by the operator.
Exporting is the connection of CHOP channels to parameters of operators. The output of each exporting CHOP is one or more channels, active only while the CHOP Viewer is on. The current value of a channel can be exported to a parameter of any operator, overriding that parameter's value. See Parameter.
Parameters in TouchDesigner are an operator's settings (numbers, menus, flags, strings, paths) which the user can alter. Parameters for any operator can be opened by right-clicking on the operator and selecting "Parameters..." A currently selected operator's parameters can be viewed in a Network Editor by pressing the keyboard shortcut 'p'.