LWRP - Reading/Writing depth

Hello everyone,

I am currently working with the LWRP and I'm experiencing some issues when working with depth.
I added a lightweight render pipeline asset to the graphic settings, enabled the depth texture and added the "Lightweight additional camera data" script to the camera.



I checked "Requires depth texture" there and added a rendertexture to the camera. As you can see I can display color without any issues, however when it comes to depth there appears to be no data.



I tried adding a depth pass to a custom shader but it doesn't seem to work there either.

Code (CSharp):

1. Pass
2.         {
3.             Name "DepthOnly"
4.             Tags{"LightMode" = "DepthOnly"}
5.  
6.             ZWrite On
7.             ColorMask 0
8.         }

I am working with the LWRP version 3.0.0 - preview.
Do you guys experience similar issues? Is there a Unity dev around who can confirm whether this is a bug?
I'm grateful for every help you can provide.

Regards,
Alex

This post is related to a shader post I made here: https://forum.unity.com/threads/transparency-using-the-lwrp.550711/, however I decided to post this question here because the issue is quite specific by now to the LWRP.

 

I'm trying to get a hold on the depth texture on a second camera as well and posted a related thread. I tried to use OnRenderImage but it seems like this is not called in the new render pipeline anymore. The new way seems to be to use the beginframeRendering or beginCameraRendering events in the renderpipeline class. Though I didn't find an example on how to do this and I didn't have the time to try a few things out.

I think in those events you can use a blit into a rendertexture with a custom material which reads the camera depth. But again.. Maybe there is another undocumented renderpipeline thing which makes this a bit easier. I hope someone who knows how to do this can reply to this thread .

 

Hey Desoxi,

could you explain to me how you got the rendertexture at the end? As described above I added a depth only pass to my shader and want to check whether it is actually writing to the depth buffer or not. It would help me a lot!

 

Hey, i just wrote the solution to this in another thread (with the whole class and shader im using).
Im using a custom post process effect to write the shader into a render texture. The only thing you need to do then is to add the "Depth Exporter" effect to the post process volume script on your camera through "Add effect -> custom-> Depth exporter".
Tell me if you have problems with it.

 

Jep i successfully did you through a custom post process effect, but the depth texture seems to be jittering and i dont know how to stabilize it. Nothing is moving, but the displacement which is driven by this depth rendertexture is jittering:
https://forum.unity.com/threads/doe...-although-the-whole-scene-stays-still.552787/
Maybe you have an idea on how to solve this..?

 

Yeah I realized that yesterday as well, not sure what I did there. Here is the current version which produces the attached image. Cube hast the LWRP Standard shader. The Hair consists of one mesh with multiple materials.

Code (CSharp):

1. Shader "LWRP/Unlit/Hair"
2. {
3.     Properties
4.     {
5.         _MainTex ("Texture", 2D) = "white" {}
6.         _Color("Color", Color) = (1, 1, 1, 1)
7.         _Cutoff("AlphaCutout", Range(0.0, 1.0)) = 0.0
8.     }
9.     SubShader
10.     {  
11.         Tags {"RenderType" = "TransparentCutout" "IgnoreProjector"="True" "Queue"="Transparent" "RenderPipeline" = "LightweightPipeline"}  
12.  
13.         //Depth only prepass
14.         Pass
15.         {
16.             Name "DepthOnly"
17.             Tags{"LightMode" = "DepthOnly"}
18.             ZWrite On
19.             ColorMask 0
20.  
21.             HLSLPROGRAM
22.  
23.             #pragma prefer_hlslcc gles
24.             #pragma exclude_renderers d3d11_9x
25.             #pragma target 2.0
26.            
27.             //#pragma shader_feature _ALPHATEST_ON
28.  
29.             #pragma vertex DepthOnlyVertex
30.             #pragma fragment DepthOnlyFragment
31.            
32.             #include "LWRP/ShaderLibrary/InputSurfaceUnlit.hlsl"
33.             #include "LWRP/ShaderLibrary/LightweightPassDepthOnly.hlsl"
34.  
35.             ENDHLSL
36.         }
37.  
38.         //Main pass
39.         Pass
40.         {
41.             Name "StandardUnlit"
42.  
43.             ColorMask RGB
44.             Blend SrcAlpha OneMinusSrcAlpha
45.             ZWrite Off
46.             Cull Off
47.  
48.             HLSLPROGRAM
49.  
50.             #pragma prefer_hlslcc gles
51.             #pragma exclude_renderers d3d11_9x
52.             #pragma target 2.0
53.  
54.             //Define vertex and fragment function
55.             #pragma vertex vert
56.             #pragma fragment frag
57.             #include "UnityCG.cginc"
58.  
59.             //Basic input
60.             struct appdata
61.             {
62.                 float4 vertex : POSITION;
63.                 float2 uv : TEXCOORD0;
64.             };
65.  
66.             //Basic fragment input
67.             struct v2f
68.             {
69.                 float2 uv : TEXCOORD0;
70.                 float4 vertex : SV_POSITION;
71.             };
72.  
73.             //Vars
74.             sampler2D _MainTex;
75.             float4 _MainTex_ST;
76.             float4 _Color;
77.             float _Cutoff;
78.            
79.             //Basic vertex function
80.             v2f vert (appdata v)
81.             {
82.                 v2f o;
83.                 o.vertex = UnityObjectToClipPos(v.vertex);
84.                 o.uv = TRANSFORM_TEX(v.uv, _MainTex);
85.                 return o;
86.             }
87.  
88.             //Alpha cutoff function
89.             void AlphaDiscard(half alpha, half cutoff, half offset = 0.0001h)
90.             {
91.                 clip(alpha - cutoff + offset);
92.             }
93.            
94.             //Basic fragment function with alpha support
95.             fixed4 frag (v2f i) : SV_Target
96.             {
97.                 half4 texColor = tex2D(_MainTex, i.uv);
98.                 half3 color = texColor.rgb * _Color.rgb;
99.                 AlphaDiscard(texColor.a, _Cutoff);
100.                 return half4(color, texColor.a);
101.             }
102.            
103.             ENDHLSL
104.         }
105.     }
106.     FallBack "Hidden/InternalErrorShader"
107. }

 

This does not show up in the frame debugger as of latest Unity 2019 May 28 2019, how do we get a custom shader to write to lwrp depth buffer?

 

I think I figured it out... Change the depth pass #includes to:

#include "Packages/com.unity.render-pipelines.lightweight/Shaders/UnlitInput.hlsl"
#include "Packages/com.unity.render-pipelines.lightweight/Shaders/DepthOnlyPass.hlsl"

 

Hi,
Sorry to bump up the old thread, but it's too hard to find learning information around ...
My project is using Unity2018.4.0f1 LWRP.
How can I access and manipulate the LWRP's _CameraDepthTexture via a ScriptableRenderPass? such as Blitting the depth to a custom RT,
such as:

buf.GetTemporaryRT(customRT, size, size, 16, FilterMode.Point, RenderTextureFormat.Depth);
buf.Bilt(BuiltinRenderTextureType.Depth, customRT, blitMat) ;

the customRT is a small rect area, I want it to sample from the _CameraDepthTexture, and the purpose is to get a median value from the rect area(the customRT).

I also followed the demo LWRPScriptableRenderPass_ExampleLibrary_Project from git, but not getting lucky. The depth texture is not blitted at all, only get a 16_16 gray block of _MainTex named UnityDefault2D...

Can you please give any simple code samples for this issue? Thank you!

 

Hi, @cyuxi
I came into the same problem in my Custom SRP. Do you find any solution?
I manually set the _CameraDepthTexture


but it not working (the _CameraDepthTexture is 16x16 gray texture)

and unity gives me a warning

 

I solved this problem by manually get temporary RT as depth texture and set render target with this RT.
depthTexId is the global texture _CameraDepthTexture


and set the render target in Render method