Week 03: RBD Fracturing and setup

Crafting My Custom RBD Fracturing Setup

Houdini’s built-in fracturing tools are great, but I wanted more control over the look and behavior of my destruction. My goal is to create a custom fracture pattern that blends the radial breaks of shattered glass with the rugged complexity of concrete fractures. By taking this hybrid approach, I can refine the breakup with both artistic and structural intent before diving into contact interactions. Prioritizing fracturing first gives me a stronger foundation for the destruction workflow, allowing for more precision and realism in the final simulation.

I. RBD Prep: Fracturing, Simulation, and Collision

Using the generated tiled ground surface, I focused on capturing the primary fracture region where the photon beam impacts, creating stress-line cracks. The surrounding non-fractured areas are removed, leaving a refined fracture zone. This fractured region then serves as the foundation for the next steps, including RBD fracturing, packing, and defining the active destruction area for a more controlled and intentional breakup.

I started by gathering references for the fracturing patterns to get a solid foundation and understanding of how these fracturing lines and edges should look.

a. Preparing the Ground and Fracture Region

Imported the ground geometry, isolating only the fracture region to focus on the affected area.
Created a scattering surface constrained to the impact centroid, which is significantly smaller than the overall fracture region.

b. Generating Radial Stress-Line Patterns

Designed cutting blade grids with noise variations to introduce irregular stress-line cracks.
Scattered points on the impact centroid surface and copied the cutting blade grids onto these points.
Applied a randomized normal attribute to the copied blades to ensure varied rotations, enhancing the natural randomness of the fractures.

c. Boolean Fracturing the Ground

Used the rotated cutting blade grids to boolean fracture the ground.
Examined the fractures using exploded view to assess their distribution and realism.
Adjusted the directional bias and cone angle of the blade rotations to refine the fracture pattern further, ensuring a balance between structural integrity and artistic control.

This structured approach ensures that the radial fractures maintain both physical plausibility and artistic intent, forming the foundation for a controlled destruction workflow.

1. Radial-Based Boolean Fracture

A. Stress line Fracturing

The radial fractures in my setup are driven by the impact of a photon beam striking the ground, generating stress-line cracks similar to those observed in high-energy impacts. To create this effect, I followed a structured process:

2. Detail Fracturing: In-Radial Concrete Pieces Fracturing

For refining the fracture details within the stress-line fractured pieces, I followed a structured approach using Voronoi fracturing in combination with attribute-based scattering and masking techniques. The process involved the following key steps:

1. Generating Fracture Patterns with Attribute-Based Scattering

Utilized a Voronoi Fracture node to create the initial fracture pattern.
Scattered points based on attribute masks created in an Attribute Wrangle, ensuring fracture density varies according to stress-line intensity.
Transferred these attribute-driven scatter points onto the ground geometry, allowing the fracture pattern to be dictated by localized impact stress areas rather than uniform distribution.

2. Refining the Fracture Structure

Organized the fracture into multiple detail levels, incorporating mask-based density control:
- Large Fragments: Defined using density masking in key impact regions.
- Mid-Size Fragments: Generated through additional density-based scattering, refining fracture granularity.
Merged these different levels to achieve a multi-scale fracture complexity, balancing structural integrity and destruction realism.

II. COLLISION SETUP

In this section, I created collisions for the foreground pillar and statue assets by simulating their interaction with the destruction elements in the short setup. Using the Static Object Collision shelf tool, I applied collision to these environment assets.

III. Setting Up the RBD Ground Simulation

To simulate the major fragments of the fractured ground, I established a basic RBD simulation using Houdini’s RBD object from the rigid body shelf tool. This setup serves as the foundation for the destruction sequence, ensuring realistic collision interactions and preparing the scene for the upcoming velocity forces.

1. Creating the RBD Simulation Network

Used the RBD Object from the rigid body shelf tool to generate an AutoDOP Network.
Routed the AutoDOP Network through an RBD Packed Object Node inside the RBD ground simulation container, allowing for an optimized and efficient simulation workflow.

2. Integrating Collision Geometries

Imported the collision geometries for the foreground environment assets, which I had created earlier.
Ensured proper collision interaction between the fractured ground and surrounding elements, enhancing the realism of the simulation.

3. Preparing for Velocity Forces

Structured the scene to have all necessary collisions preconfigured, reducing setup time for the next stage.
With the collisions in place, I can focus entirely on integrating velocity forces in the coming week, streamlining the simulation process and allowing for precise control over fragment movement.

By setting up the collision groundwork first, I’m ensuring a smoother workflow when introducing dynamic forces, ultimately leading to a more refined and controlled destruction simulation.