RBD Car Fracture geometry node

Fracture a RBD Car Rig.

Since

21.0

This node allows you to fracture a RBD Car Rig. It provides options to fracture various materials, and creates all the constraints needed for sheet metal deformations, glass fracturing, and wood shards while allowing for some level of customization by diving inside.

See the RBD Car Fracture page in the Destruction chapter for more information.

Parameters ¶

Chassis Group

Specify the rigid chassis group onto which the wheels will be attached. The chassis geometry will have a single “body” name and can be used by the RBD Car Deform SOP for suspension deformations as well as the RBD Car Follow Path SOP to drive the vehicle along a path in DOPs.

Ignore Group

Specify geometry to be ignored and not have a proxy geo representation.

Rest Frame

Specify a reference frame at which the fracturing and constraints will be performed to avoid the expensive operations from being time dependent.

Re-Align Wheels

If the input RBD Car has steering and wheel animation (after an RBD Car Follow Path SOP with Animate Wheels and Suspensions on, or following a driving simulation), you will need to re-align the wheels and adjust the steering in order to avoid double transforms and the wheels spinning around the incorrect axis.

Display ¶

Display

Guides & Preview

Hides the output mesh and only shows the input mesh while showing preview guide geometry of the various sections' fracturing options.

Geometry

Shows the output geometry.

Constraints

Shows the output constraint geometry.

Proxy Geometry

Shows the output proxy geometry.

Section

All

Displays the preview guide geometry for all sections.

Section Names

Select the section name which you want to show the preview guide geometry.

Isolate Section Geo

Only shows the selected Section's input geometry, when Display is set to Guides & Preview.

Hide Other Section Geo when Selecting

Hides the geometry that has already been set as other sections' Group geometry when selecting the various section’s Group geometry. This helps declutter the viewport as you set various sections up.

Guides ¶

Show Sections

Assign a unique color to the output geometry by section, making it easier to visually identify the various sections.

Show Section Connector Constraints

Show the constraints created between sections as guide geometry.

Tires ¶

Tires can be fractured to achieve soft-body-like behavior or to allow them to be shredded. This approach differs slightly from how other sections are fractured. The proxy geometry is generated dynamically in a more optimized manner, and only the pieces still connected to the remaining wheel geometry or rims are constrained to the wheels. The tire constraints are set up as Soft constraints without plasticity, rather than starting as Glue constraints followed by Soft constraints.

Tires Group

Select the tire geometry. It is important to leave the rim geometry unselected in order to ensure the wheels stay attached to the car.

Fracture Density

The voronoi point density.

Edge Detail ¶

Edge Detail

Use booleans for fracturing and add noise to the voronoi fracture patterns to break up the edge detail.

Detail Size

The size of the polygons added for the edge detail.

Noise Amplitude

The amplitude of the edge detail noise.

Noise Element Size

The size of the noise pattern. Higher values give larger scaled details in the noise.

Sections ¶

Sections

Specifies how many sections the input RBD car geometry will be divided into for fracturing.

Enable

Enable the fracturing of the section.

Group

Specify the geometry to be fractured in this section.

Name

The base name of the section’s fractured geometry.

Material

The various materials have different options for fracturing and will typically have different constraint settings.

Glass

Choose between Safety and Impact fracture Type.

Metal

Choose between Sheet and Solid fracture Type.

Wood

Creates wood-like splinter fractures along each pieces' longest bounding box axis.

Rubber

Voronoi fractures with Soft constraints and no plasticity for a rubbery soft-body like behavior.

Type

When Material is Glass,

Safety

Generates evenly sized Voronoi hexagonal fractures similar to safety glass. The glue constraints can optionally turn into soft constraints with plasticity enabled, allowing for the typical deformations seen in windshields under minor impacts, before eventually breaking into small individual pieces.

Impact

Interactively place an impact fracture pattern on the glass panes you want to fracture.

When Material is Metal,

Sheet

This option is meant for thin geometry, which scatters fractures along the surface for crumpling and bending effects. It always has plastic deformations on, as it’s typically used for crumpling effects. The constraint anchors are placed at the extremities of the geometry to allow bending along edges.

Solid

This option is for volumetric fracturing of solid chunks of metal.

Enable Plastic Deformations

When turned on, the safety glass and metals will have the next constraint enabled and set to Soft with plasticity attributes enabled.

Constrain to Neighbor Sections

Turning this off will not constrain pieces to neighboring sections. This is useful when you want to create your own constraints, such as hinges for the hood, trunk, or doors.

Fracture Density

The voronoi point density.

Seed

The impact glass fracture pattern’s random seed.

Impact

The 2D coordinate of the impact around which the cracks will radiate from.

Size

The size of the 2D crack pattern.

Radial Cracks

Specify a minimum number of radial cracks. Depending on the noise and other branching probabilities, radial cracks may stop being generated before this number is reached as cracks merge or coalesce.

Branch Probability

Specify the probability for crack branches to appear. These are radial cracks that spawn off radial cracks.

Concentric Crack Probability:

Specify the probability for concentric cracks to appear. These cracks run around the impact point in circles.

Translate

Amount of translation along xyz axes.

Scale

Non-uniform scaling along xyz axes.

Rotate

Amount of rotation along xyz axes.

Thicken

Detect non-manifold pieces and extrude the proxy geometry, post-fracture, to give the geometry some thickness for collisions.

Thickness

Specify the thickness for the extruded proxy geometry.

Edge Detail ¶

Edge Detail

When Material is set to Metal, or Material is set to Glass and Type is set to Safety, use boolean and add noise to the voronoi fracture patterns to break up the edge detail.

Detail Size

The size of the polygons added for the edge detail.

Noise Amplitude

The amplitude of the edge detail noise.

Noise Element Size

The size of the noise pattern. Higher values give larger scaled details in the noise.

Constraints ¶

Do Color

Add color to the section constraints for visual identification.

Color

Specify the color to use.

Strength Scale

Scale the section Glue constraints' strength attribute.

Stiffness Scale

Scale the section Soft constraints' stiffness attribute.

Angular Stiffness Scale

Scale the section Soft constraints' angularstiffness attribute.

Constraints ¶

Section Connector Constraints ¶

Create Section Connector Constraints

Enables the automatic creation of constraints between sections.

Search Radius

Specify the maximum allowed distance when searching for nearby points.

Breakable Chassis Connectors

Glue constraints connecting pieces to the chassis will be allowed to break when enabled.

Strength

The strength of the Glue constraints.

Strength Variance

Randomly varies this fraction of Glue constraints' strength attribute.

Switch Constraint Type

Allows Glue constraints to turn into Soft constraints when they break.

Enable Plasticity

Ensures the Soft constraints have plasticity enabled and the required attributes are set in order to achieve plausible plastic deformations, when Switch Constraint Type is turned on.

Constraint Attributes ¶

Strength Scale

Scale the generated Glue constraints' strength attribute.

Stiffness Scale

Scale the generated Soft constraints' stiffness and angularstiffness attributes.

Plasticity Stiffness Scale

Scale the generated Soft constraints' plastichardening and angularplastichardening attributes.

Input Constraints ¶

Suspension Stiffness Scale

Scale the input RBD Car Rig’s suspension stiffness attribute.

Disable Motors

Remove the input RBD Car Rig’s Hard constraints with motors enabled.

Retarget Anchors

Specify the wheels and fans or propellers which should be constrained to geometry other than the chassis geometry. This is useful when you need to destroy part of the chassis where wheels and fans are attached to.

RBDs ¶

Poly Reduce Proxy Geometry

Reduces the proxy geometry complexity for better performance.

Compute Collision Padding

When turned on, auto-computes the bullet_collision_margin and bullet_shrink_amount attributes (collision padding) based on the pieces' bounding box size.

Default Padding

When Compute Collision Padding is turned on, this is the default padding for larger pieces.

Padding Ratio

When Compute Collision Padding is turned on, this is the padding is set to this ratio of the smallest value of the pieces' bounding box size.

Match Input Density

Scale the various pieces' density attribute in order to match the input RBD Car’s total mass. This helps ensure some similarity in behavior during the simulation between the unfractured input RBD Car and the RBD Fractured Car.

Body Density Scale

Scale the fractured pieces from the input RBD Car’s body, density attribute.

Wheel Density Scale

Scale the wheels' density attribute.