Faster Physics

Each of the performance-enhancing suggestions we've explored so far has been primarily centered on reducing resource costs and avoiding frame rate issues. However, at its most fundamental level, seeking peak performance means improving the user experience. This is because every frame rate hiccup, every crash, and every system requirement that is too costly for a given market ultimately detracts from the quality of the product. Physics engines are a unique category of subsystems whose behavior and consistency contributes a significant factor toward product quality. Spending the time to improve their behavior is often worth the cost.

If important collision events get missed, the game freezes while it calculates a complex physics event, or the player falls through the floor, these scenarios have an obvious and significant negative impact on the quality of gameplay...

Understanding the physics engine

Unity technically features two different physics engines: Nvidia's PhysX for 3D physics and the open source project Box2D for 2D physics. However, their implementations are highly abstracted, and from the perspective of the higher-level Unity API that we configure through the main Unity engine, both physics engine solutions operate in a functionally identical fashion.

In either case, the more we understand about Unity's physics engines, the more sense we can make of possible performance enhancements. So, first, we'll cover the theory about how Unity implements these systems.

Physics and time

Physics engines generally operate under the assumption that time advances by fixed values...

Physics performance optimizations

In this section, we will go over several techniques, optimizations, tricks, and settings that will allow your game to extract every drop of physics performance from your game. This includes how to set up your scene, learn when to use static colliders, how to configure the Collision Matrix, when to use triggers instead of Rigidbodies, and much more. Let's go over all of these, one by one.

Scene setup

Firstly, there are several best practices we can apply to our scenes to improve the consistency of the physics simulation. Note that several of these techniques will not necessarily improve CPU or memory usage, but they will result in a reduced likelihood of instability from the physics engine...

Summary

We've covered numerous methods to improve our game's physics simulation both in terms of performance and consistency. The best technique when it comes to costly systems such as physics engines is simply avoidance. The less we need to use the system, the less we need to worry about it generating bottlenecks. In the worst-case scenario, we may need to reduce the scope of our game to condense physics activity down to only the essentials, but as we've learned, there are plenty of ways to reduce physics complexity without causing any noticeable gameplay effects.

In the next chapter, we will immerse ourselves in Unity's Rendering Pipeline and discover how to maximize the graphical fidelity of our application, by making use of all of the CPU cycles we've freed up using the performance enhancements from earlier chapters.

...