Scriptable Render Pipeline introduction

This page explains how Unity’s Scriptable Render Pipeline (SRP) works, and introduces some key concepts and terminology. The information on this page is applicable to the Universal Render PipelineA series of operations that take the contents of a Scene, and displays them on a screen. Unity lets you choose from pre-built render pipelines, or write your own. More info
See in Glossary (URP), the High Definition Render Pipeline (HDRP), and custom render pipelines that are based on SRP.

The Scriptable Render Pipeline is a thin API layer that lets you schedule and configure rendering commands using C# scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
See in Glossary. Unity passes these commands to its low-level graphics architecture, which then sends instructions to the graphics API.

URP and HDRP are built on top of SRP. You can also create your own custom render pipeline on top of SRP.

Render Pipeline Instance and Render Pipeline Asset

Every render pipeline based on SRP has two key customized elements:

• A Render Pipeline Instance. This is an instance of a class defines the functionality of your render pipeline. Its script inherits from RenderPipeline, and overrides its Render() method.
• A Render Pipeline Asset. This is an asset in your Unity Project that stores data about which Render Pipeline Instance to use, and how to configure it. Its script inherits from RenderPipelineAsset and overrides its CreatePipeline() method.

For more information on these elements, and instructions on how to create them in a custom render pipeline, see Creating a Render Pipeline Asset and a Render Pipeline Instance.

ScriptableRenderContext

ScriptableRenderContext is a class that acts as an interface between the custom C# code in the render pipeline and Unity’s low-level graphics code.

Use the ScriptableRenderContext API to schedule and execute rendering commands. For information, see Scheduling and executing rendering commands in the Scriptable Render Pipeline.

Entry points and callbacks

When working with SRP, use these to make Unity call your C# code at specific times.

• RenderPipeline.Render is the main entry point to the SRP. Unity calls this method automatically. If you are writing a custom render pipeline, this is where you begin to write your code.
• The RenderPipelineManager class has the following events that you can subscribe to, so that you can execute custom code at specific points in the render loop:
  • beginFrameRendering - Note: This can generate garbage. Use beginContextRendering instead.
  • endFrameRendering - Note: This can generate garbage. Use endContextRendering instead.
  • beginContextRendering
  • endContextRendering
  • beginCameraRendering
  • endCameraRendering