Feature Request VFX Collide With Depth Buffer in URP?

I spent some time trying to get the node to work within the LTS version of URP and the Visual Effects Graph (7.5.3). It didn't work, but it seems like it should work.

I started writing a VFX binder that tried to inject the camera information it needed, simply converting the HDRP version-- but I got stuck and decided to try upgrading.

After upgrade I now get this handy message that it's simply not supported! Well crap!


Though it seems like it should be possible for it to work provided that the depth buffer is bound properly. Is there anything I could do to get it to work? Or is it something in the works that I could wait for? It'd be really handy for weather effects!

 

Thanks so much! Right now it seems like it requires a Texture2DArrray, and I'm struggling to figure out why. Though I'll poke around with trying to pass my depth texture as a variety of different Texture2DArrays and see what happens.

 

I figured it out! I just made the following edits to the Visual Effects package:
com.unity.visualeffectgraph@7.5.3/Editor/Types/VFXTypes.cs:

Code (CSharp):

1. // Line 300, switched this
2.         [Tooltip("The depth buffer of the camera, containing the rendered depth information.")]
3.         public Texture2DArray depthBuffer;
4.         [Tooltip("The color buffer of the camera, containing the rendered color information.")]
5.         public Texture2DArray colorBuffer;
6. // With this:
7.         [Tooltip("The depth buffer of the camera, containing the rendered depth information.")]
8.         public Texture2D depthBuffer;
9.         [Tooltip("The color buffer of the camera, containing the rendered color information.")]
10.         public Texture2D colorBuffer;
11.  

com.unity.visualeffectgraph@7.5.3/Editor/Expressions/VFXExpressionCamera.cs:

Code (CSharp):

1. // Line 158, I switched this:
2. sealed protected override VFXExpression Evaluate(VFXExpression[] constParents) { return VFXValue.Constant<Texture2DArray>(null); }
3. // With this:
4. sealed protected override VFXExpression Evaluate(VFXExpression[] constParents) { return VFXValue.Constant<Texture2D>(null); }
5.  

com.unity.visualeffectgraph@7.5.3/Editor/Models/Blocks/Implementations/Collision/CollisionDepth.cs:

Code (CSharp):

1. // Basically replaced all texture array lookups with standard ones.
2. // I'll go over each line and its replacement anyway for clarity:
3. // Line 97, switched
4. float depth = LoadTexture(Camera_depthBuffer,int4(uv*Camera_pixelDimensions, 0, 0)).r;
5. // with
6. float depth = LoadTexture(Camera_depthBuffer,int3(uv*Camera_pixelDimensions, 0)).r;
7.  
8. // ...
9.  
10. // Line 123, switched
11. float depth10 = LoadTexture(Camera_depthBuffer, int4(depthPos10, 0, 0)).r;
12.         float depth01 = LoadTexture(Camera_depthBuffer, int4(depthPos01, 0, 0)).r;
13. // With
14. float depth10 = LoadTexture(Camera_depthBuffer, int3(depthPos10, 0)).r;
15.         float depth01 = LoadTexture(Camera_depthBuffer, int3(depthPos01, 0)).r;
16.  
17.  

Then I created a default VFX graph with these settings:


And used a custom binder to just-- set a property to the _CameraDepthTexture global:
VFXDepthBinder.cs

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.Rendering;
5.  
6. namespace UnityEngine.VFX.Utility
7. {
8.     [AddComponentMenu("VFX/Property Binders/Depth Binder")]
9.     [VFXBinder("Depth/Depth")]
10.     class VFXDepthBinder : VFXBinderBase {
11.         public string Property { get { return (string)m_Property; } set { m_Property = value; UpdateSubProperties(); } }
12.         [VFXPropertyBinding("UnityEditor.VFX.Depth"), SerializeField, UnityEngine.Serialization.FormerlySerializedAs("m_Parameter")]
13.         protected ExposedProperty m_Property = "DepthTexture";
14.         private ExposedProperty DepthBuffer;
15.         private Texture depthTexture;
16.         protected override void OnEnable() {
17.             base.OnEnable();
18.             UpdateSubProperties();
19.         }
20.  
21.         void OnValidate() {
22.             UpdateSubProperties();
23.         }
24.  
25.         void UpdateSubProperties() {
26.             DepthBuffer = m_Property;
27.         }
28.  
29.         public override bool IsValid(VisualEffect component) {
30.             return component.HasTexture((int)DepthBuffer);
31.         }
32.  
33.         public override void UpdateBinding(VisualEffect component) {
34.             if (depthTexture == null) {
35.                 depthTexture = Shader.GetGlobalTexture("_CameraDepthTexture");
36.             }
37.             component.SetTexture((int)DepthBuffer, depthTexture);
38.         }
39.  
40.         public override string ToString() {
41.             return string.Format("Depth : '{0}' -> {1}", m_Property, depthTexture == null ? "(null)" : depthTexture.ToString());
42.         }
43.     }
44. }

And it works!

There was only a couple of gotchas:
1. it doesn't work in the editor (unless you're playing).
2. The camera(s) needs to be tagged as "MainCamera".
3. And finally the Camera portion of the CollideDepth node needs to be set to worldspace (W instead of L, easy to miss).

I've also published my changes to a fork on github here: https://github.com/naelstrof/com.unity.visualeffectgraph/tree/7.5.3-cwdb-urp

 

Holy moly thank you so mutch!

 

As a follow up, if you need a camera that isn't the main camera. I wrote an extra CameraBinder here:

https://github.com/naelstrof/com.un...ertyBinding/Implementation/URPCameraBinder.cs

It requires you to set the Camera to output to a RenderTexture, and to specify it to the binder, but it works! The gotchas for this one is that the Camera MUST be in perspective mode, and the RenderTexture needs to be outputting depth.

 

In new Unity input Depth buffer have grey input, when output 2d Sampler have red input. Anybody knows how to connect them now?

 

Hi, did you made a pull request of this or have any plans to update this fork to Visual Effect Graph 10.8?

 

I stopped maintaining the branch because it was such a hassle. I did describe all the changes that need to happen in post #4 though! Sorry!

 

Thanks naelstrof, your solution was very helpful.

I made a version of URPCameraBinder that works with perspective and orthographic cameras. (Still assumed world-space VFX). https://gist.github.com/Ohmnivore/46cdffe3bd55814c4f413d87fa589bbc#file-urpcamerabinder-cs

I didn't need to modify the VFX graph package. I'm on 15.0.5 and Unity 2023.1.

There's some additional files in there to render a heightmap in URP (ex for a rain VFX).