Week 06: Refining RBD Fracturing and Other Attribute
I. Refining Ground Fracturing Setup
1. Improved Fracturing Technique
Building on the initial stress-line-based fracturing from the earlier setup, this week I refined the approach to make the fracture generation more procedural and art-directable. Instead of using static scatter patterns, I introduced a density attribute system to control the fracture concentration dynamically from the impact centroid.
The new workflow involved:
Procedural Density-Based Point Scattering
Using the earlier attribute-based scattering as a foundation, I enhanced it by generating a density attribute mapped from the impact region outward.
Points for the Voronoi fracture were scattered according to this density, automatically creating denser fracture zones near the impact center and a gradual falloff as the distance increases.
The density control was sharpened by shaping the attribute using a
maskfromtargetSOP, allowing for highly focused fracture zones with fine-tuned edge blending.
Multi-Scale Fracture Layering
Large, medium, and fine fragments were organized based on the procedural density mask, achieving natural structural breakup without manually tuning individual zones.
This layering maintained realism by concentrating detail where the stress was highest, while keeping larger, intact sections farther from the impact.
By upgrading the system to be density-driven and procedural, the fracture setup became far easier to iterate, fine-tune, and art-direct — a significant step forward compared to the earlier more manually scattered approach.
II. Setting Up the Active Attribute And Visualization
This week, I also focused on refining the activation control for fractured pieces during simulation. To move beyond static or manually-painted activation, I developed a solver-based activation system that reacts dynamically to the simulation environment.
The updated workflow involved:
Procedural Growth of Activation Mask
Using a Solver SOP, the activation mask was made to grow naturally over time, triggered by contact between the fractured ground and the colliders.
A maskfromgeometry SOP was used inside the solver to progressively expand the activation zone, allowing pieces to activate based on localized impacts rather than a single predefined event.
This setup enabled much more natural, reactive fracturing behavior during collisions.
Point-Based Visualization
To clearly monitor the activation state, a point-based visualization was created showing which fractured pieces had been activated at each frame.
This helped quickly diagnose the behavior of the dynamic system and ensure that activation matched collision input.
While the procedural activation system introduced a major step forward in realism, it also revealed critical issues that needed fixing. Because the @active attribute values were not standardized (sometimes falling between 0 and 1 due to mask interpolation), fractured pieces would sometimes "wake up" early, drift unintentionally, or lose structural integrity before real impact forces hit them.
2. Velocity Attribute Improvements
Velocity shaping played a key role as well. Instead of relying purely on default physics, I implemented a custom impact-based velocity system tailored to the shot, allowing me to sculpt speed and directionality in a more controlled way. This gave the destruction a much stronger sense of intent—where each fragment moved with purpose rather than random force. Here is a peek into the VOP Network for the custom speed shaping and vector’s directional control:
