The Scriptable Render Pipeline (SRP) Batcher is a draw call optimization that significantly improves performance for applications that use an SRP. The SRP Batcher reduces the CPU time Unity requires to prepare and dispatch draw calls for materials that use the same shader variant.
This section includes information about the render pipeline compatibility of the SRP Batcher.
|功能||内置渲染管线||通用渲染管线 (URP)||高清渲染管线 (HDRP)||Custom Scriptable Render Pipeline (SRP)|
In any given scene, some GameObjects are compatible with the SRP Batcher, and some aren’t. Compatible GameObjects use the SRP Batcher code path, and non-compatible GameObjects use the standard SRP code path. For more information, see How the SRP Batcher works.
A GameObject must meet the following requirements to be compatible with the SRP Batcher code path:
All lit and unlit shaders in the High Definition Render Pipeline (HDRP) and the Universal Render Pipeline (URP) fit this requirement (except for the particle versions of these shaders).
For a custom shader to be compatible with the SRP Batcher it must meet the following requirements:
UnityPerDraw. For example,
You can check the compatibility status of a shader in the Inspector panel.
This section contains information on how to use the SRP Batcher in Unity’s pre-built Scriptable Render Pipelines.
要在 URP 中激活 SRP Batcher，请执行以下操作：
Unity does not show certain advanced properties in the URP Asset by default. To see all available properties:
In the URP Asset, in any section, click the vertical ellipsis icon (⋮) and select Show Additional Properties
Unity shows all available properties in the current section.
To show all additional properties in all sections:
Click the vertical ellipsis icon and select Show All Additional Properties. Unity opens the Core Render Pipeline section in the Preferences window.
In the property Additional Properties > Visibility, select All Visible.
When you use HDRP, Unity enables the SRP Batcher by default. Disabling the SRP Batcher is not recommended. However, you can temporarily disable the SRP Batcher for debugging purposes.
To enable and disable the SRP Batcher at build time using the Editor:
1.在 Project 窗口中选择 HDRP 资源。 2. In the Inspector for the asset, enter Debug mode. In Debug mode, you can see the properties of the HDRP Asset, including the SRP Batcher property. 3. Select Enable SRP Batcher to enable or disable the SRP Batcher.
To enable or disable the SRP Batcher at runtime, toggle the following global variable in your C# code:
GraphicsSettings.useScriptableRenderPipelineBatching = true;
The traditional way to optimize draw calls is to reduce the number of them. Instead, the SRP Batcher reduces render-state changes between draw calls. To do this, the SRP Batcher combines a sequence of
draw GPU commands. Each sequence of commands is called an SRP batch.
To achieve optimal performance for your rendering, each SRP batch should contain as many
draw commands as possible. To achieve this, use as few shader variants as possible. You can still use as many different materials with the same shader as you want.
When Unity detects a new material during the render loop, the CPU collects all properties and binds them to the GPU in constant buffers. The number of GPU buffers depends on how the shader declares its constant buffers.
The SRP Batcher is a low-level render loop that makes material data persist in GPU memory. If the material content doesn’t change, theSRP Batcher doesn’t make any render-state changes. Instead, the SRP Batcher uses a dedicated code path to update the Unity Engine properties in a large GPU buffer, like this:
Here, the CPU only handles the Unity Engine properties, labeled Per Object large buffer in the above diagram. All materials have persistent constant buffers located in GPU memory, which are ready to use. This speeds up rendering because:
In some rare cases, you might want to intentionally make particular GameObjects incompatible with the SRP Batcher. For example, if you want to use GPU instancing, which isn’t compatible with the SRP Batcher. If you want to render many identical meshes with the exact same material, GPU instancing can be more efficient than the SRP Batcher. To use GPU instancing, you must either:
There are two ways to remove compatibility with the SRP Batcher from a GameObject:
Tip: If you use GPU instancing instead of the SRP Batcher, use the Profiler to make sure that GPU instancing is more efficient for your application than the SRP Batcher.
You can make both hand-written and Shader Graph shaders incompatible with the SRP Batcher. However, for Shader Graph shaders, if you change and recompile the Shader Graph often, it’s simpler to make the renderer incompatible instead.
To make a Unity shader incompatible with the SRP Batcher, you need to make changes to the shader source file:
Propertiesblock. Don’t declare the new material property in the
The material property doesn’t need to do anything; just having a material property that doesn’t exist in the
UnityPerMaterial constant buffer makes the shader incompatible with the SRP Batcher.
Warning: If you use a Shader Graph, be aware that every time you edit and recompile the Shader Graph, you must repeat this process.
You can make individual renderers incompatible with the SRP Batcher. To do this, add a
MaterialPropertyBlock to the renderer.
You can check the status of SRP batches in the Frame Debugger window. Each SRP Batch displays how many draw calls Unity used, which keywords Unity attached to the shader, and the reason why Unity didn’t batch that draw call with the previous one.
要检查 SRP Batcher 批次的状态，请执行以下操作：
In the example below, the reason is: Nodes have different shaders. This means that the shader for that SRP batch os different to the one in the previous SRP batch. Because the SRP Batcher used a different shader, the SRP Batcher created a new batch. If several SRP batches have a low number of draw calls, it often means the project uses too many shader variants.
If you write your own Scriptable Render Pipeline, instead of using either the Universal Render Pipeline or the High Definition Render Pipeline, try to write a generic multi-purpose shader with a minimal number of keywords. This is optimal because you can use as many material properties as you want.