| On this page |
The Voronoi Fracture Configure Object DOP takes a simulation object
and attaches the data which is needed for it to be dynamically
fractured by the 
Voronoi Fracture
Solver, using impact data generated by
the 
RBD Solver. It also creates new DOP objects
for any pieces created by fracturing 
RBD Objects.
This DOP can be applied to any active RBD Object or
RBD Packed Object, including those created by
RBD Point Object, RBD Glue Object,
or 
RBD Fractured Object.
You can add noise to the velocity impulse applied by this
DOP by connecting a 
Noise DOP to the second input of the node, which adds the noise as subdata of the Voronoi Fracture data.
Using Make Breakable
-
Select the object you want to break, and click the
RBD Object tool on the Rigid Bodies tab.Note
Once you convert geometry to an RBD object you can only transform, rotate, and scale it when it is on the first frame.
-
Make sure the new object is selected and click the
Make Breakable tool on the Rigid Bodies tab.
For specific parameter help see the Voronoi Fracture
Configure Object dynamics node help.
Parameters
Group
Which objects to apply the configuration to.
Impact
Parameters on this tab control when the object to which this data is applied can fracture.
Impact Group
An impact with objects in the specified group can potentially cause this object to fracture.
Min/Max Impact
The minimum impact impulse that can cause this object to fracture. Any impact over the minimum can cause a fracture; the range is used in conjunction with the Radius Scale parameter, allowing heavier impacts to map to a larger impact radius.
The minimum impact gets mapped to the minimum impact radius scale, and the maximum impact force gets mapped to the maximum impact scale. Having a maximum ensures that values are clipped so that really strong impacts from creating huge impact zone.
Minimum Volume
The minimum volume an object must have to be eligible for fracturing. The object’s volume is calculated by dividing its mass by its density.
Note
This volume only work this way if you turn on Compute Mass on your RBD Objects. If you don’t, the volume will not be what you expect and you may have to just set it to 0.
Re-fracture Delay
The interval (in seconds of simulation time) after an object fractures before it can be eligible for fracturing again.
Fracture From Magnet Force Metaballs
Use the metaball geometry associated with any 
Magnet
Forces applied to the object as a source for
potential fracturing. This can be used to cause explosion-type
effects, where the magnet force itself causes the fracture.
Minimum Magnet Volume
The minimum ratio of the object’s collision volume that must be overlapped by the magnet metaball before fracturing can occur. It can be useful to delay the fracturing until the metaball overlaps much of the object’s volume when using animated metaball geometry.
Maximum Fractures
Controls how many times the object can break. A maximum fracture of 1 will break on the first impact, but the resulting pieces won’t break again. A maximum fracture of 2 will allow all the pieces from the first fracture to break.
Note
When some pieces break off the main chunk, the main chunk is still considered a "piece", which means it will lose one of its max fractures.
Impact Radius
The radius of the metaball to be copied to each impact point.
Min/Max Scale
Scale the impact radius by this amount, based upon the ranges specified in the Minimum Impact parameter. Radius scale multiplies the Impact Radius gives you the size of metaball around each impact point. So given a single point of impact, it is roughly your crater radius. There are two values for the min/max.
Points
Parameters on this tab control the generation of fracture points from
the eligible impacts. See the 
Voronoi Fracture
Points SOP help for more information.
Compute Number of Fracture Points
Calculates the number of points to scatter in each fracture region based on its surface area.
Points Per Area
The number of points per unit of surface area. This can be scaled by the Point Density parameter for each region.
Number of Points
The number of points to generate.
Per Impact
Whether the Number of Points parameter specifies the total number of generated points or the number of generated points for each impact point.
Show Fracture Points
Displays the generated points. Yellow is for the surface region, red for the interior, and blue for the exterior.
Surface
Point Density
The density of point generation for this region. If Compute Number Of Points is enabled, this parameter is a multiplier of the Points Per Area value. If an explicit Number of Points value is being used, this parameter determines the proportion of those points allocated to this region.
Surface Offset
The amount to offset the generated points from the object surface. Offsetting by a small amount can cause smaller, more debris-like fractured pieces from the Surface region.
Radius Scale
The amount to scale the impact radius before calculating the Surface region.
Clustering
Use Fracture Settings
Use the parameters on the Cluster tab to control the size of the clustered pieces.
Disabled
Disable clustering for every fractured piece from this region.
Single Piece
Cluster all pieces in this region together as a single piece.
Interior
Point Density
The density of point generation for this region. If Compute Number Of Points is enabled, this parameter is a multiplier of the Points Per Area value. If an explicit Number of Points value is being used, this parameter determines the proportion of those points allocated to this region.
Clustering
Use Fracture Settings
Use the parameters on the Cluster tab to control the size of the clustered pieces.
Disabled
Disable clustering for every fractured piece from this region.
Single Piece
Cluster all pieces in this region together as a single piece.
Exterior
Point Density
The density of point generation for this region. If Compute Number Of Points is enabled, this parameter is a multiplier of the Points Per Area value. If an explicit Number of Points value is being used, this parameter determines the proportion of those points allocated to this region.
Scatter Location
At Impact
Scatter points at the boundary of the Interior and Exterior regions.
Exterior Volume
Scatter points throughout the exterior volume.
Both
Scatter points at both of the above locations.
Impact Offset
The offset of the Interior / Exterior boundary when scattering using the At Impact or Both setting above.
Clustering
Use Fracture Settings
Use the parameters on the Cluster tab to control the size of the clustered pieces.
Disabled
Disable clustering for every fractured piece from this region.
Single Piece
Cluster all pieces in this region together as a single piece.
Fracture
Parameters on this tab control the fracturing of the geometry from the
generated fracture points. See the 
Voronoi
Fracture SOP help for more information.
Cusp Interior Normals
Computes vertex normals on the edges of the interior geometry, so that they will have a cusped appearance.
Cusp Interior Normals Angle
Computes vertex normals on the edges of the interior geometry with angles greater than this angle, so that they will have a cusped appearance.
Cusp Exterior Normals
Computes vertex normals on the edges of the input geometry, so that they will have a cusped appearance. If the input geometry already has normals, you may want to disable this.
Cusp Exterior Normals Angle
Computes vertex normals on the edges of the input geometry with angles greater than this angle, so that they will have a cusped appearance. If the input geometry already has normals, you may want to disable this.
Cut
Cut Plane Offset
Offsets the cut plane between adjacent cell points before cutting. Increasing this has the effect of putting space between each fractured piece.
Note
Setting this parameter to a non-zero value disables Clustering.
Cluster
Cluster Pieces
Fuse the individual pieces into larger clusters based on their input points sharing a common, non-zero cluster attribute value. Values for this attribute can come from the generated fracture points, or from noise as specified below.
Size
The size of the cells for the noise added to the input points. This roughly corresponds to the size of the clusters.
Offset
The offset of the cellular noise added to the interior points.
Jitter
The jitter of the cellular noise added to the interior points.
Random Detachment
Randomly detach pieces from clusters.
Detach Seed
The random seed used for detachment.
Detach Ratio
The probability that a particular piece will be detached.
Interior Detail
Add Interior Detail
Adds additional polygons to the interior surfaces of pieces.
Detail Size
The size of the polygons added to the interior surfaces.
Noise Type
The type of noise added to the interior points.
Frequency
The frequency of the noise added to the interior points.
Offset
The offset of the noise added to the interior points.
Turbulence
The turbulence of the noise added to the interior points.
Depth / Noise Scale Bias
The value for the bias curve that maps depth within the surface to the amplitude of the noise applied.
Velocity Transfer
Parameters on this tab control how velocity is transferred from the intact object to the fractured pieces at the time of impact. Fractured pieces can inherit velocity from the intact object’s pre- and post-impact velocity. At the time of fracture, a velocity impulse is also calculated for each fracturing impact, and is added to the pieces' point velocities with a user-specified strength and falloff. This impulse can add velocity to the pieces even when the intact object has no velocity before or after impact.
Pre/Post Velocity Bias
The amount of pre- or post-impact velocity that the fractured pieces should inherit.
Setting this to a low value (biased towards pre-impact velocity) makes the pieces inherit little of the object’s collision response, and the object will appear brittle, with little internal strength.
Setting this to a high value (biased towards post-impact velocity) causes the pieces to inherit much of the object’s collision response, and the object will appear harder, with more internal strength.
Impulse Distance
The distance over which the velocity impulse falls off from each impact. The impulse will have no effect past this distance.
Radial Impulse Scale
A scale for the radial component of the velocity impulse. Increasing this value will give velocity in an outwards direction from the fracturing impacts to the pieces within the Impulse Distance.
Normal Impulse Scale
A scale for the normal component of the velocity impulse. Increasing this value will give velocity (in the direction of the collision response) to the pieces within the Impulse Distance, even if the velocity bias for the entire object is towards pre-impact velocities.
Default Operation
Controls the Parameter Operations for the underlying data.
New Pieces Group
The name of the group to contain any newly created pieces from
this DOP, for the timestep in which they are created. This
group can be used in subsequent DOPs to override any
simulation values inherited from the pieces' parent object,
using DOPs such as 
RBD State or 
Physical
Parameters.
Inputs
First Input
This optional input can be used to control which simulation objects are modified by this node. Any objects connected through this input and which match the Group parameter field will be modified.
If this input is not connected, this node can be used in conjunction with an Apply Data node, or can be used as an input to another data node.
All Other Inputs
If this node has more input connectors, other data nodes can be attached to act as modifiers for the data created by this node.
The specific types of subdata that are meaningful vary from node to
node. Click 
an input connector to see a list of available
data nodes that can be meaningfully attached.
Outputs
First Output
The operation of this output depends on what inputs are connected to this node. If an object stream is input to this node, the output is also an object stream containing the same objects as the input (but with the data from this node attached).
If no object stream is
connected to this node, the output is a data output. This data
output can be connected to an 
Apply Data DOP,
or connected directly to a data input of another data node, to
attach the data from this node to an object or another piece of
data.
Locals
channelname
This DOP node defines a local variable for each channel and parameter on the Data Options page, with the same name as the channel. So for example, the node may have channels for Position (positionx, positiony, positionz) and a parameter for an object name (objectname).
Then there will also be local variables with the names positionx, positiony, positionz, and objectname. These variables will evaluate to the previous value for that parameter.
This previous value is always stored as part of the data attached to the object being processed. This is essentially a shortcut for a dopfield expression like:
dopfield($DOPNET, $OBJID, dataName, "Options", 0, channelname)
If the data does not already exist, then a value of zero or an empty string will be returned.
DATACT
This value is the simulation time (see variable ST) at which the current data was created. This value may not be the same as the current simulation time if this node is modifying existing data, rather than creating new data.
DATACF
This value is the simulation frame (see variable SF) at which the current data was created. This value may not be the same as the current simulation frame if this node is modifying existing data, rather than creating new data.
RELNAME
This value will be set only when data is being attached to a relationship (such as when Constraint Anchor DOP is connected to the second, third, of fourth inputs of a Constraint DOP).
In this case, this value is set to the name of the relationship the data to which the data is being attached.
RELOBJIDS
This value will be set only when data is being attached to a relationship (such as when Constraint Anchor DOP is connected to the second, third, of fourth inputs of a Constraint DOP).
In this case, this value is set to a string that is a space separated list of the object identifiers for all the Affected Objects of the relationship to which the data is being attached.
RELOBJNAMES
This value will be set only when data is being attached to a relationship (such as when Constraint Anchor DOP is connected to the second, third, of fourth inputs of a Constraint DOP).
In this case, this value is set to a string that is a space separated list of the names of all the Affected Objects of the relationship to which the data is being attached.
RELAFFOBJIDS
This value will be set only when data is being attached to a relationship (such as when Constraint Anchor DOP is connected to the second, third, of fourth inputs of a Constraint DOP).
In this case, this value is set to a string that is a space separated list of the object identifiers for all the Affector Objects of the relationship to which the data is being attached.
RELAFFOBJNAMES
This value will be set only when data is being attached to a relationship (such as when Constraint Anchor DOP is connected to the second, third, of fourth inputs of a Constraint DOP).
In this case, this value is set to a string that is a space separated list of the names of all the Affector Objects of the relationship to which the data is being attached.
ST
This value is the simulation time for which the node is being evaluated.
This value may not be equal to the current Houdini time
represented by the variable T, depending on the settings of the 
DOP
Network Offset Time and Time Scale
parameters.
This value is guaranteed to have a value of zero at the
start of a simulation, so when testing for the first timestep of a
simulation, it is best to use a test like $ST == 0 rather than
$T == 0 or $FF == 1.
SF
This value is the simulation frame (or more accurately, the simulation time step number) for which the node is being evaluated.
This value may not be equal to the current Houdini frame number
represented by the variable F, depending on the settings of the DOP
Network parameters. Instead, this value is equal to
the simulation time (ST) divided by the simulation timestep size
(TIMESTEP).
TIMESTEP
This value is the size of a simulation timestep. This value is useful to scale values that are expressed in units per second, but are applied on each timestep.
SFPS
This value is the inverse of the TIMESTEP value. It is the number of timesteps per second of simulation time.
SNOBJ
This is the number of objects in the simulation. For nodes that
create objects such as the 
Empty Object node,
this value will increase for each object that is evaluated.
A good way to guarantee unique object names is to use an expression
like object_$SNOBJ.
NOBJ
This value is the number of objects that will be evaluated by the current node during this timestep. This value will often be different from SNOBJ, as many nodes do not process all the objects in a simulation.
This value may return 0 if the node does not
process each object sequentially (such as the 
Group
DOP).
OBJ
This value is the index of the specific object being processed by the node. This value will always run from zero to NOBJ-1 in a given timestep. This value does not identify the current object within the simulation like OBJID or OBJNAME, just the object’s position in the current order of processing.
This value is useful for generating a
random number for each object, or simply splitting the objects into
two or more groups to be processed in different ways. This value
will be -1 if the node does not process objects sequentially (such
as the Group DOP).
OBJID
This is the unique object identifier for the object being processed. Every object is assigned an integer value that is unique among all objects in the simulation for all time. Even if an object is deleted, its identifier is never reused.
The object identifier can always be used to uniquely identify a given object. This makes this variable very useful in situations where each object needs to be treated differently. It can be used to produce a unique random number for each object, for example.
This value is also the best way
to look up information on an object using the dopfield expression
function. This value will be -1 if the node does not process objects
sequentially (such as the Group DOP).
ALLOBJIDS
This string contains a space separated list of the unique object identifiers for every object being processed by the current node.
ALLOBJNAMES
This string contains a space separated list of the names of every object being processed by the current node.
OBJCT
This value is the simulation time (see variable ST) at which the current object was created.
Therefore, to check if an object was created
on the current timestep, the expression $ST == $OBJCT should
always be used. This value will be zero if the node does not process
objects sequentially (such as the Group DOP).
OBJCF
This value is the simulation frame (see variable SF) at which the current object was created.
This value is equivalent to using the
dopsttoframe expression on the OBJCT variable. This value will be
zero if the node does not process objects sequentially (such as the
Group DOP).
OBJNAME
This is a string value containing the name of the object being processed.
Object names are not guaranteed to be unique within a simulation. However, if you name your objects carefully so that they are unique, the object name can be a much easier way to identify an object than the unique object identifier, OBJID.
The object name can
also be used to treat a number of similar objects (with the same
name) as a virtual group. If there are 20 objects named "myobject",
specifying strcmp($OBJNAME, "myobject") == 0 in the activation field
of a DOP will cause that DOP to operate only on those 20 objects. This
value will be the empty string if the node does not process objects
sequentially (such as the Group DOP).
DOPNET
This is a string value containing the full path of the current DOP Network. This value is most useful in DOP subnet digital assets where you want to know the path to the DOP Network that contains the node.
Note
Most dynamics nodes have local variables with the same names as the
node’s parameters. For example, in a 
Position node,
you could write the expression:
$tx + 0.1
…to make the object move 0.1 units along the X axis at each timestep.
Inputs
First
The simulation objects to make fractureable by attaching the appropriate data.
Outputs
First
The simulation objects that are passed into this node are output with the data required for them to be fractureable.
Locals
ST
This value is the simulation time for which the node is being evaluated.
This value may not be equal to the current Houdini time
represented by the variable T, depending on the settings of the DOP
Network Offset Time and Time Scale
parameters.
This value is guaranteed to have a value of zero at the
start of a simulation, so when testing for the first timestep of a
simulation, it is best to use a test like $ST == 0 rather than
$T == 0 or $FF == 1.
SF
This value is the simulation frame (or more accurately, the simulation time step number) for which the node is being evaluated.
This value may not be equal to the current Houdini frame number
represented by the variable F, depending on the settings of the DOP
Network parameters. Instead, this value is equal to
the simulation time (ST) divided by the simulation timestep size
(TIMESTEP).
TIMESTEP
This value is the size of a simulation timestep. This value is useful to scale values that are expressed in units per second, but are applied on each timestep.
SFPS
This value is the inverse of the TIMESTEP value. It is the number of timesteps per second of simulation time.
SNOBJ
This is the number of objects in the simulation. For nodes that
create objects such as the Empty Object node,
this value will increase for each object that is evaluated.
A good way to guarantee unique object names is to use an expression
like object_$SNOBJ.
NOBJ
This value is the number of objects that will be evaluated by the current node during this timestep. This value will often be different from SNOBJ, as many nodes do not process all the objects in a simulation.
This value may return 0 if the node does not
process each object sequentially (such as the Group
DOP).
OBJ
This value is the index of the specific object being processed by the node. This value will always run from zero to NOBJ-1 in a given timestep. This value does not identify the current object within the simulation like OBJID or OBJNAME, just the object’s position in the current order of processing.
This value is useful for generating a
random number for each object, or simply splitting the objects into
two or more groups to be processed in different ways. This value
will be -1 if the node does not process objects sequentially (such
as the Group DOP).
OBJID
This is the unique object identifier for the object being processed. Every object is assigned an integer value that is unique among all objects in the simulation for all time. Even if an object is deleted, its identifier is never reused.
The object identifier can always be used to uniquely identify a given object. This makes this variable very useful in situations where each object needs to be treated differently. It can be used to produce a unique random number for each object, for example.
This value is also the best way
to look up information on an object using the dopfield expression
function. This value will be -1 if the node does not process objects
sequentially (such as the Group DOP).
ALLOBJIDS
This string contains a space separated list of the unique object identifiers for every object being processed by the current node.
ALLOBJNAMES
This string contains a space separated list of the names of every object being processed by the current node.
OBJCT
This value is the simulation time (see variable ST) at which the current object was created.
Therefore, to check if an object was created
on the current timestep, the expression $ST == $OBJCT should
always be used. This value will be zero if the node does not process
objects sequentially (such as the Group DOP).
OBJCF
This value is the simulation frame (see variable SF) at which the current object was created.
This value is equivalent to using the
dopsttoframe expression on the OBJCT variable. This value will be
zero if the node does not process objects sequentially (such as the
Group DOP).
OBJNAME
This is a string value containing the name of the object being processed.
Object names are not guaranteed to be unique within a simulation. However, if you name your objects carefully so that they are unique, the object name can be a much easier way to identify an object than the unique object identifier, OBJID.
The object name can
also be used to treat a number of similar objects (with the same
name) as a virtual group. If there are 20 objects named "myobject",
specifying strcmp($OBJNAME, "myobject") == 0 in the activation field
of a DOP will cause that DOP to operate only on those 20 objects. This
value will be the empty string if the node does not process objects
sequentially (such as the Group DOP).
DOPNET
This is a string value containing the full path of the current DOP Network. This value is most useful in DOP subnet digital assets where you want to know the path to the DOP Network that contains the node.
Note
Most dynamics nodes have local variables with the same names as the
node’s parameters. For example, in a Position node,
you could write the expression:
$tx + 0.1
…to make the object move 0.1 units along the X axis at each timestep.
Examples
The following examples include this node.
FractureExamples Example for Voronoi Fracture Solver dynamics node
PlateBreak Example for TimeShift geometry node
| See also |
Voronoi Fracture Parameters
