In this lesson, you will learn how to use the Chaos Visual Debugger (CVD) to pinpoint exactly why your physics objects are jittering, clipping, or flying off into the void.
When physics simulations behave erratically—such as an object vibrating uncontrollably or passing through a wall—it is often difficult to see what the solver is "thinking." The Chaos Visual Debugger acts as a flight recorder for your physics world. By capturing simulation data, you can step through frames to see exactly how forces, collisions, and constraints are being resolved.
Accessing the Visual Debugger
To begin, you must enable the ChaosVD plugin in your project settings. Once active, you can connect to a running simulation or load a recorded trace file. You can trigger a recording manually via the console command p.Chaos.Solver.Debug.Record 1.
Diagnosing Common Issues
Once your trace is loaded, focus on these three specific areas:
- Collision Overlaps: Look at the "Contacts" view. If you see thousands of tiny contacts generated in a single frame, your objects are likely "interpenetrating" (stuck inside each other). This causes the solver to apply massive restorative forces, resulting in the object "exploding."
- Force Application: Use the "Forces" overlay to visualize vectors acting on your Rigid Body. If you see an unexpected force vector pushing an object away from your character, you know an external Physics Field or a constraint is misconfigured.
- Solver Instability: Check for "Solver Iterations." If an object is connected via several constraints, the solver might struggle to find a stable solution. In the debugger, you can see if constraints are "broken" or exceeding their maximum tension limits.
By slowing down the simulation time in the CVD interface, you can observe the exact moment a physics interaction causes a velocity spike. Instead of guessing why a car is bouncing, you can see the precise frame where the collision normal flips, allowing you to adjust your Collision Presets or Mass Properties with surgical precision.
Key Takeaway: The Chaos Visual Debugger allows you to inspect collision contacts and force vectors frame-by-frame, turning mysterious physics glitches into measurable, fixable data points.