To fetch the previous frames that the cameraA component which creates an image of a particular viewpoint in your scene. The output is either drawn to the screen or captured as a texture. More info
See in Glossary rendered in 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), use the UniversalCameraData.historyManager
API. These textures are sometimes called history textures or history buffers.
The frames are the output of the GPU rendering pipeline, so they don’t include any processing that occurs after GPU rendering, such as post-processingA process that improves product visuals by applying filters and effects before the image appears on screen. You can use post-processing effects to simulate physical camera and film properties, for example Bloom and Depth of Field. More info post processing, postprocessing, postprocess
See in Glossary effects.
To fetch previous frames from outside a scriptable render pass, refer to Get data from previous frames in a script.
Follow these steps:
In the RecordRenderGraph
method, get the UniversalCameraData
object from the ContextContainer
object. For example:
public override void RecordRenderGraph(RenderGraph renderGraph, ContextContainer frameContext) { UniversalCameraData cameraData = frameContext.Get<UniversalCameraData>(); }
To request access to either the color textures or the depth textures in the rendering history, use the RequestAccess
API. For example:
// Request access to the color textures cameraData.historyManager.RequestAccess<RawColorHistory>();
Use RawDepthHistory
instead to request access to the depth textures.
Get one of the previous textures. For example:
// Get the previous textures RawColorHistory history = cameraData.historyManager.GetHistoryForRead<RawColorHistory>(); // Get the first texture, which the camera rendered in the previous frame RTHandle historyTexture = history?.GetPreviousTexture(0);
Convert the texture into a handle the render graph system can use. For example:
passData.historyTexture = renderGraph.ImportTexture(historyTexture);
You can then read the texture in the render pass.
For more information about using the historyManager
API, refer to UniversalCameraData.historyManager
.
The following is a Scriptable Renderer Feature that creates a material and uses the previous frame as the material’s texture.
To use the example, follow these steps:
_BaseMap
. For an example, refer to Drawing a texture.RenderLastFrameInMaterial.cs
, paste the following code into it, and save the file.using UnityEngine; using UnityEngine.Rendering; using UnityEngine.Rendering.Universal; using UnityEngine.Rendering.RenderGraphModule; public class RenderLastFrameInMaterial : ScriptableRendererFeature { public Material objectMaterial; CustomRenderPass renderLastFrame; public override void Create() { renderLastFrame = new CustomRenderPass(); renderLastFrame.renderPassEvent = RenderPassEvent.BeforeRenderingOpaques; } public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData) { renderLastFrame.passMaterial = objectMaterial; renderer.EnqueuePass(renderLastFrame); } class CustomRenderPass : ScriptableRenderPass { public Material passMaterial; public class PassData { internal Material material; internal TextureHandle historyTexture; } public override void RecordRenderGraph(RenderGraph renderGraph, ContextContainer contextData) { UniversalCameraData cameraData = contextData.Get<UniversalCameraData>(); // Return if the history manager isn't available // For example, there are no history textures during the first frame if (cameraData.historyManager == null) { return; } // Request access to the color and depth textures cameraData.historyManager.RequestAccess<RawColorHistory>(); using (var builder = renderGraph.AddRasterRenderPass<PassData>("Get last frame", out var passData)) { UniversalResourceData resourceData = contextData.Get<UniversalResourceData>(); // Set the render graph to render to the active color texture builder.SetRenderAttachment(resourceData.activeColorTexture, 0, AccessFlags.Write); // Add the material to the pass data passData.material = passMaterial; // Get the color texture the camera rendered to in the previous frame RawColorHistory history = cameraData.historyManager.GetHistoryForRead<RawColorHistory>(); RTHandle historyTexture = history?.GetPreviousTexture(0); passData.historyTexture = renderGraph.ImportTexture(historyTexture); builder.SetRenderFunc(static (PassData data, RasterGraphContext context) => { // Set the material to use the texture data.material.SetTexture("_BaseMap", data.historyTexture); }); } } } }
To get data from previous frames in a script, for example a MonoBehaviour
, do the following:
RequestAccess
API to request the texture.UniversalAdditionalCameraData.history
API to get the data.To make sure Unity finishes rendering the frame first, use the UniversalAdditionalCameraData.history
API in the LateUpdate
method.
For more information, refer to the following in the Scriptable Render Pipeline (SRP) Core package:
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