Adding detph to channel alpha

I'm trying to simulate a RGBD camera with unity. So far I added a script from this thread https://answers.unity.com/questions/877170/render-scene-depth-to-a-texture.html and is working well.
I made a small modification to the

frag

method to linearly control the depth sample, here is the code:

Code (CSharp):

1.     fixed4 frag(output o) : COLOR
2.     {
3.         float depth = UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, o.uv));
4.         return fixed4(depth, depth, depth, 1);
5.     }

I want to save a png image with the RGB channels unchanged, but with its alpha channel using the depth information that I rescued from the previous method. I need these images to train a neural network, so it is important to use that format.
I am really new to shaders. I suppose that sampling directly from the camera should do the work, but I don't know how to do that in the fragment state, or any. I'm looking for something like these or similar:

Code (CSharp):

1.     fixed4 frag(output o, float red, float green, float blue) : COLOR
2.     {
3.         float depth = UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, o.uv));
4.         return fixed4(red, green, blue, depth);
5.     }

Thanks

 

The more important question is how / when are you rendering this shader? If you're doing this as a

Blit()

, presumably as part of an

OnRenderImage()

c# function, then you'll need to pass the render texture source to the

Blit()

, and sample it in the shader. See the default Image Effect shader when you create one in the Project view for a basic example.

Then add the code to sample the depth texture and output that as the alpha, with the RGB from the texture.

Code (csharp):

1. half4 frag(v2f i) : SV_Target
2. {
3.     half4 color = tex2D(_MainTex, i.uv);
4.     float depth = UNITY_SAMPLE_DEPTH(tex2D(_CameraDepthTexture, i.uv));;
5.     return half4(color.rgb, depth);
6. }

If instead you're rendering this as a mesh in front of the camera with a high material queue, you just need to use

ColorMask A

and output the depth as the color value (

return float4(depth, depth, depth, depth);

).
https://docs.unity3d.com/Manual/SL-Pass.html

 

I actually was rendering with

Blit()

in the

OnRenderImage()

method as you said. I tried the modifications that you proposed and it worked excellently. Thank you.

 

Hello
I am a Korean developer
Can you tell me how you solved it?