The Universal Render Pipeline (URP, previously known as Lightweight RP) uses an integrated Volume system for Post Processing effects, sometimes referred to as Post Processing V3 / PPv3. These effects include things like Bloom, Chromatic Aberration, Depth of Field, Color Adjustments, Tonemapping, Vignette, etc. Note that URP does not have Ambient Occlusion yet, it’s on the roadmap, but you may also be able to find solutions on the asset store.
Sections :
PPv2
The “Post Processing” package listed in the Package Manager, also known as the Post Processing Stack V2 (PPv2), is intended for use with the built-in pipeline. Some versions of URP that are supported by Unity 2019.4 LTS (around URP v7.2 to v7.4?) support PPv2, however newer versions from v8.0 onwards will not, so using the integrated Volume system is recommended.
If you are upgrading an existing project, there is currently no easy way to convert from PPv2 to PPv3 as far as I’m aware, it has to be done manually. If you still want to use PPv2 instead, there should be an option on the URP Asset to switch the Post Processing “Feature Set” from the integrated solution to “Post Processing V2”.
This option will only show when the package is installed, and of course you need to be using a LWRP/URP version that supports PPv2 (Unity 2019.4 LTS, v7.2 to v7.4? I’ve tested with Unity 2019.3.3f1 and URP v7.3.1).
With this set, you can then continue using the Post-Process Layer and Post-Process Volume components on objects, see here for more information on using PPv2. Note that certain features might not be supported (Ambient Occlusion, Temporal Anti-aliasing and Motion Blur).
You’ll also want to make sure Post Processing is enabled on the Camera, in order to see the effects in the game view! You can also find screen-space Anti-aliasing here.
Integrated / PPv3
To use integrated Post Processing solution in URP, you can add the “Volume” component to a GameObject, or right-click in the Hierarchy and select something under the Volume heading.
A volume can be set as Global, where it affects the entire scene or Local, where it will also require a Collider (preferably with IsTrigger enabled) to be added. With local, the effects will only appear when the camera is inside the volume/collider. You can use the Blend Distance to create a smooth transition.
There’s also a Weight setting, which is how much the post processing effects contribute, with 0 being not at all, and 1 being fully. If you have multiple volumes overlapping or volumes inside other volumes, you will also want to use the Priority setting. The higher the value, the higher the priority.
Each Volume has a Profile which holds the Post-processing effects. Multiple volumes can share the same profile. Click the New button to create a profile, then use the Add Override button to add effects to the list. For a list & info about each effect, see here.
Each setting has a default value and will be greyed out. To edit a setting click the checkbox on the left side to override the value.
Now that there’s a volume in the scene, You’ll want to click on the Camera and make sure Post Processing is enabled, in order to see the effects in the game view. You can also find screen-space Anti-aliasing here.
The camera also has Volume Mask and Volume Trigger settings under the Environment heading. The mask includes which layers will affect the camera – any volumes on layers not included in that list will not affect the camera. The trigger setting is which transform that is used to test against local volumes. If left blank, the camera’s transform is used.
Custom Effects
Currently the integrated volume system does not support custom effects, but it is on the roadmap. We can instead apply global post processing shader effects using a custom Renderer Feature, applied to the Forward Renderer.
The feature uses a Blit, which copies the contents of a texture to a render texture, using a custom shader to apply the effect. The code for this feature is at the end of the post.
The shader should include a Texture2D property with the reference “_MainTex“, in order to obtain the input from the blit. We can then make adjustments to the image, e.g. inverting the colours via a One Minus node, and pass that into the Color input on the Master node.
The Master node should be Unlit, as this is all done in screen space where having PBR lighting would not make sense.
Note that shadergraph produces multiple passes which shouldn’t be used for the blit. The renderer feature included a Blit Material Pass Index where we can specify which pass should be used. If set to -1, all passes will be rendered (including the shadow caster which causes a large black rectangle to appear when in Opaque surface mode), setting it to 0 will use the first pass only.
Below is the full code for a feature that handles this, based on the example here. You don’t really have to understand what it does in order to use it. Just have it somewhere in your Assets, and it will be available to the Forward Renderer features list.
Alternatively you can find an updated version here which has some extra features, such as setting specific source/destinations and using the After Rendering event to correctly handle the blit with post processing effects applied.
Also if you want to be able to enable/disable a renderer feature at runtime, you can obtain a public reference to it to achieve that. See an example here.
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;
// Saved in Blit.cs
public class Blit : ScriptableRendererFeature {
public class BlitPass : ScriptableRenderPass {
public enum RenderTarget {
Color,
RenderTexture,
}
public Material blitMaterial = null;
public int blitShaderPassIndex = 0;
public FilterMode filterMode { get; set; }
private RenderTargetIdentifier source { get; set; }
private RenderTargetHandle destination { get; set; }
RenderTargetHandle m_TemporaryColorTexture;
string m_ProfilerTag;
public BlitPass(RenderPassEvent renderPassEvent, Material blitMaterial, int blitShaderPassIndex, string tag) {
this.renderPassEvent = renderPassEvent;
this.blitMaterial = blitMaterial;
this.blitShaderPassIndex = blitShaderPassIndex;
m_ProfilerTag = tag;
m_TemporaryColorTexture.Init("_TemporaryColorTexture");
}
public void Setup(RenderTargetIdentifier source, RenderTargetHandle destination) {
this.source = source;
this.destination = destination;
}
public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData) {
CommandBuffer cmd = CommandBufferPool.Get(m_ProfilerTag);
RenderTextureDescriptor opaqueDesc = renderingData.cameraData.cameraTargetDescriptor;
opaqueDesc.depthBufferBits = 0;
// Can't read and write to same color target, use a TemporaryRT
if (destination == RenderTargetHandle.CameraTarget) {
cmd.GetTemporaryRT(m_TemporaryColorTexture.id, opaqueDesc, filterMode);
Blit(cmd, source, m_TemporaryColorTexture.Identifier(), blitMaterial, blitShaderPassIndex);
Blit(cmd, m_TemporaryColorTexture.Identifier(), source);
} else {
Blit(cmd, source, destination.Identifier(), blitMaterial, blitShaderPassIndex);
}
context.ExecuteCommandBuffer(cmd);
CommandBufferPool.Release(cmd);
}
public override void FrameCleanup(CommandBuffer cmd) {
if (destination == RenderTargetHandle.CameraTarget)
cmd.ReleaseTemporaryRT(m_TemporaryColorTexture.id);
}
}
[System.Serializable]
public class BlitSettings {
public RenderPassEvent Event = RenderPassEvent.AfterRenderingOpaques;
public Material blitMaterial = null;
public int blitMaterialPassIndex = -1;
public Target destination = Target.Color;
public string textureId = "_BlitPassTexture";
}
public enum Target {
Color,
Texture
}
public BlitSettings settings = new BlitSettings();
RenderTargetHandle m_RenderTextureHandle;
BlitPass blitPass;
public override void Create() {
var passIndex = settings.blitMaterial != null ? settings.blitMaterial.passCount - 1 : 1;
settings.blitMaterialPassIndex = Mathf.Clamp(settings.blitMaterialPassIndex, -1, passIndex);
blitPass = new BlitPass(settings.Event, settings.blitMaterial, settings.blitMaterialPassIndex, name);
m_RenderTextureHandle.Init(settings.textureId);
}
public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData) {
var src = renderer.cameraColorTarget;
var dest = (settings.destination == Target.Color) ? RenderTargetHandle.CameraTarget : m_RenderTextureHandle;
if (settings.blitMaterial == null) {
Debug.LogWarningFormat("Missing Blit Material. {0} blit pass will not execute. Check for missing reference in the assigned renderer.", GetType().Name);
return;
}
blitPass.Setup(src, dest);
renderer.EnqueuePass(blitPass);
}
}
For more examples, there’s a good example of an Outline Shader here, by Alexander Ameye. It produces a similar effect to the image at the top of this post and is made using two renderer features. The first feature is used to redraw the scene with an overrideMaterial to capture the normals of objects in the scene in a texture, which is then used in the outline shader (as well as the depth texture). That shader is then blitted to the screen using a similar render feature to the above Blit feature.
The UniversalRenderingExamples here also provide some examples of using render features for a few effects.
Cyan 