Unity游戏物理异常求助：刚体搭建的墙体/塔体无故晃动

Hey there, I’ve dealt with exactly this kind of rigid body drift issue when building stacked primitive structures—super frustrating, right? Let’s walk through the key physics settings and tweaks that should fix the unwanted sway:

1. Tweak Individual Rigid Body Properties #

• Disable unnecessary gravity: If your wall/tower isn’t supposed to be affected by gravity, double-check that the Use Gravity toggle is turned off for every cube. Even tiny gravitational forces can accumulate over time and cause gradual drift.
• Freeze unneeded movement axes: Head to the Constraints section of each rigid body and freeze rotation on all three axes (Freeze Rotation X/Y/Z). If your structure is meant to stay completely in place, freeze all translation axes too—this prevents any accidental movement from solver errors.
• Adjust sleep thresholds: Most physics engines (like Unity’s PhysX or Unreal’s Chaos) put rigid bodies to "sleep" when they’re stationary to save computation. If the sleep threshold is too low, tiny numerical errors can wake the body over time. Increase the Sleep Threshold (or split Linear Sleep Threshold/Angular Sleep Threshold) for each cube—this tells the engine to keep the body asleep unless it receives a force above that threshold.

2. Adjust Global Physics Engine Settings #

• Increase solver iterations: The physics solver’s iteration count determines how accurately collisions and constraints are resolved. Low iterations can lead to tiny positional errors that build up over hours/days. Try doubling the default Solver Iterations (or Position Iterations/Velocity Iterations) in your project’s global physics settings—this makes the solver more precise at keeping your cubes aligned.
• Disable CCD for static structures: Continuous Collision Detection (CCD) is designed for fast-moving objects to prevent tunneling. Enabling it on stationary stacked cubes introduces unnecessary calculations that can cause drift. Turn off Continuous Dynamic or CCD for your cubes unless they need to interact with fast-moving objects.
• Tweak gravity scale (if needed): If you do need gravity for your scene, try reducing the global gravity scale slightly. Even a small reduction (like from 9.8 to 9.0) can prevent cumulative drift in stacked rigid bodies.

3. Optimize Collision Setup #

• Switch to static rigid bodies (if possible): If your wall/tower is never going to move or be destroyed, switch each cube from a dynamic rigid body to a static rigid body. This completely removes physics simulation for the objects, eliminating all drift entirely.
• Use convex colliders: If you need dynamic rigid bodies (e.g., for destructibility), use convex colliders instead of mesh colliders. Mesh colliders can have precision issues that cause tiny, repeated forces between adjacent cubes over time. Convex colliders are simpler and more stable for stacked structures.
• Adjust collision margin: Most colliders have a small "skin width" or collision margin to prevent floating-point errors. If this margin is too small, the engine might detect false contact points between cubes, leading to gradual movement. Increase the Collision Margin slightly for each cube’s collider—this helps the engine handle contact points more reliably.

4. Quick Troubleshooting Checks #

• Scan for hidden forces: Make sure no scripts are accidentally applying tiny forces (like AddForce or AddTorque) to the cubes over time. Even a force of 0.001 can accumulate and cause noticeable sway after hours.
• Precisely align cubes: Use snap-to-grid tools when placing your cubes to ensure they’re perfectly aligned with no overlapping colliders. Even a tiny overlap can cause the physics solver to push cubes apart gradually.

内容的提问来源于stack exchange，提问作者javier romero