Question Cull Pixels Inside Overlapping Primitive

Hello Unity Community,

Using HDRP 2021.2.0b15.3666

Is it possible to cull pixels that fall inside of another overlapping primitive. So you have Sphere A with culling Shader on it along with a Cullme script, then Sphere B touches/overlaps a portion of Sphere A. All pixels from Sphere A, that fall inside Sphere B, then get culled off of Sphere A. Sphere B is transparent.

I am very determined to continue working inside HDRP and really could use a nudge in the right direction with this. I am trying to recreate the L4D effect of culling a mesh and then showing another mesh hidden underneath (insides).

I got this half working with a CGPROGRAM shader file copied from another user (sorry I don't recall the source). Tried adding that to a Custom Node (String and File) in Shader Graph and hitting a wall. Do I need to sign up for Unity HDRP Shader Classes or is this something someone here can help me with? Is that even a thing? If I wanted to pay someone to make this as an HDRP LIT shader that can be culled, where would I post for that?

Attached is a zip file of a short video showing the CGPROGRAM shader in action, in this HDRP project.

Any help is appreciated.

Code (CSharp):

1.  Shader "CGShader5"
2.      {
3.          SubShader
4.          {
5.              Pass
6.              {
7.                  /*Cull Off*/
8.    
9.                  CGPROGRAM
10.    
11.                  #pragma vertex vert
12.                  #pragma fragment frag
13.    
14.                  uniform float4x4 _CullerSpace;
15.    
16.                  struct vout
17.                  {
18.                      float4 pos : SV_POSITION;
19.                      float4 worldpos : TEXCOORD0;
20.                      float4 localpos : TEXCOORD1;
21.                      float4 cullerpos : TEXCOORD2;
22.                  };
23.    
24.                  vout vert(float4 vertex : POSITION)
25.                  {
26.                      vout _out;
27.                      _out.pos = UnityObjectToClipPos(vertex);
28.                      //_out.pos = mul(Unity_Matrix_VP, Unity_ObjectToWorld), (vertex);
29.                      _out.localpos = vertex;
30.                      _out.worldpos = mul(unity_ObjectToWorld, vertex);
31.                      _out.cullerpos = mul(_CullerSpace, _out.worldpos);
32.                      return _out;
33.                  }
34.    
35.                  float4 frag(vout _in) : COLOR
36.                  {
37.                      /*return float4(_in.cullerpos.x, _in.cullerpos.y, 0, 1);*/
38.    
39.                      if (_in.cullerpos.x > -0.5 && _in.cullerpos.x < 0.5 &&
40.                          _in.cullerpos.y > -0.5 && _in.cullerpos.y < 0.5 &&
41.                          _in.cullerpos.z > -0.5 && _in.cullerpos.z < 0.5)
42.                          discard;
43.    
44.                      return float4(0, 1, 0, 1);
45.                  }
46.    
47.                  ENDCG
48.              }
49.          }
50.      }

Code (CSharp):

1.  using UnityEngine;
2. [ExecuteInEditMode]
3. public class CullMe : MonoBehaviour
4. {
5.      public Transform culler;
6.      void Update()
7.      {
8.          if (!culler)
9.              return;
10.          var renderer = GetComponent<Renderer>();
11.          if (!renderer)
12.              return;
13.          var material = renderer.sharedMaterial;
14.          material.SetMatrix("_CullerSpace", culler.worldToLocalMatrix);
15.      }
16. }

 

I am fairly confident this post will resolve my issue. Going to try this out and get back to here with results tomorrow.

https://forum.unity.com/threads/how...out-the-intersection-of-other-objects.638872/

 

I can't seem to get this working. Not sure if something has changed with ShaderGraph from this article has changed. I tried recreating in a URP project and still not working. Frustrating..

This script seems to be working fine, I can see the exposed parameters on the object I want to Cull being updated in realtime. I am pretty sure I recreated the Graph exactly how it's showing in this other setup.Pictures attached.

Code (CSharp):

1.  using UnityEngine;
2. [ExecuteInEditMode]
3.  
4. public class CullMe : MonoBehaviour
5. {
6.      public Transform culler;
7.      public float radius = 1;
8.      void Update()
9.      {
10.          if (!culler)
11.              return;
12.          var renderer = GetComponent<Renderer>();
13.          if (!renderer)
14.              return;
15.          var material = renderer.sharedMaterial;
16.          material.SetVector("_CullerParams", new Vector4 (culler.transform.position.x, culler.transform.position.y, culler.transform.position.z, radius));
17.        
18.      }
19. }

Is anyone else able to try and replicate the effect from this article using HDRP? Any help is appreciated.

 

I think this is in the wrong forum, could a @moderator move this to the Graphics\ShaderGraph forum please?

 

Getting closer, user error. I was messing around with the values and I noticed that if I highlighted the sphere being culled, the outline was actually moving the closer I got with the Culling sphere. So I swapped Position with UV(Geometry) and it's actually dissolving it now, just need some more tweaks and will post the final result.