Physics Profiler 模块

The Physics Profiler module displays information about the physics that the physics system has processed in your project’s scene. This information can help you diagnose and resolve performance issues or unexpected discrepancies related to the physics in your project’s scene. You can also use the Physics Debug Visualization to further debug and understand issues with physics in your application.

图表类别

The Physics Profiler module’s chart tracks the time your application spends on physics. The timings are divided into different chart categories. To change the order of the categories in the chart, you can drag them in the chart’s legend. You can also click a category’s colored legend to toggle its display. When you click on the chart, you can see the exact numerical values of each chart category in the module details pane below the chart.

模块详细信息面板

When you click on the Physics Profiler module, the module details pane displays further information about the physics in your project’s scene.

The numbers displayed in the Profiler might not correspond to the exact number of GameObjects with physics components in your Scene. This is because Unity processes some physics components at a different rate depending on which other components affect it (for example, an attached Joint component). To calculate the exact number of GameObjects with specific physics components attached, you must write a custom script with the FindObjectsOfType function.

The Physics Profiler module doesn’t display the number of sleeping Rigidbody components. These are components which don’t engage with the physics system, so the Profiler doesn’t process them. For more information on sleeping Rigidbody components, see the documentation on Rigidbody.

Understanding physics performance issues

物理模拟在主逻辑更新循环的单独固定频率更新周期中运行，只能通过每次调用的 Time.fixedDeltaTime 推进时间。这类似于 Update 和 FixedUpdate 之间的区别。有关更多信息，请参阅关于 Time 窗口的文档。

当一个复杂逻辑或图形帧需要很长时间时，此性能分析器必须每帧多次调用物理模拟。这意味着已经占用大量资源的帧会占用更多的时间和资源。这可能导致物理模拟会根据 Maximum Allowed Timestep 值而暂时停止；这个值可在 Project Settings 窗口（菜单：__Edit > Project Settings > Time__）中设置。

要在项目中检测到这一点，请选择 CPU Usage Profiler 模块 并在 Hierarchy 视图中的 Overview 部分中检查 Physics.Processing 或 Physics.Simulate 的调用次数。

In this example image, the value of 2 in the Calls column indicates that the physics simulation was called two times over the last logical frame.

A call count close to 10 might indicate an issue. As a first solution, reduce the frequency of the physics simulation, and if the issue continues, check what might have caused the heavy frame before the physics system had to use a lot of simulation calls to catch up with the game time. Sometimes, a heavy graphics frame might cause more physics simulation calls later on in a Scene.

For more detailed information about the physics simulation in your Scene, select the search box at the top of the module details pane, search for Physics.Processing, and then select Calls from the dropdown at the top right of the pane. This displays the names of the physics system tasks that run to update your Scene. The two most common names you’re likely to see are:

• Pxs: short for ‘PhysX solver’, which are physics system tasks that joints require as well as resolving contacts for overlapping Rigidbody components.
• ScScene: used for tasks that update the Scene, run the broad phase and narrow phase, and integrate Rigidbody components (moving them in space due to forces and impulses). For more information, see Steven M. LaValle’s work on Planning Algorithms for a definition on two-phase collision detection phases.

Legacy Physics Profiler module

You can switch to the Legacy mode to see the older version of the Physics Profiler module, which was the default module in older versions of Unity. To do this, select Legacy from the dropdown menu in the top right of the Physics Profiler module’s details pane.

In this mode, you can load and inspect Profiler data that was saved in an older version of Unity. If you switch to this mode to inspect data captured in a newer version of Unity, then the data displayed is unreliable and inaccurate. You should always use the Current mode to inspect new Physics Profiler data.