Drawing Anti-Aliased cube to RenderTexture gives edge artifacts

I want to draw a cube to a RenderTexture and then display that texture somewhere else (UI primarily)
This cube needs to be able to support anti-aliasing.

The issue I'm running into is that the edges of the cube get anti-aliased with the "Clear Flags" color of the camera, leaving a nasty edge artifact when displaying the image on a different color background.

Exact setup:

• Camera
  • Clear Flags: Solid Color
  • Background: RGBA 255 255 255 0
  • Target Texture: RenderTexture
• RenderTexture
  • Anti-aliasing: 8 samples
• Cube - drawn by camera above
  • Shader: Custom shader (see below)
  • 45° rotation on all axes
  • Color: RGBA 98 112 140 255
• Plane - outside camera, only visible in editor
  • Material created by dragging the RenderTexture onto the plane
    • Shader: Unlit/Transparant

Custom shader:

Code (csharp):

1.  
2. Shader "Unlit Color Only" {
3.     Properties {
4.         _Color ("Color", Color) = (0,0,0,0)
5.     }
6.    
7.     SubShader {
8.         Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" }
9.         Blend One OneMinusSrcAlpha
10.         Color [_Color]
11.         Pass {}
12.     }
13. }
14.  

The edge artifact result:

The color of the edge is derived from the clear color of the camera.

How can I get rid of these edge artifacts while maintaining anti-aliasing transparency?

 

It looks like RT is low res. What's the resolution you're using for rendering on render texture?

 

That should be RGBA 0 0 0 0. Solid black and fully transparent. That alone will get you a dark outline instead of a bright outline. After that you need to be using a premultiplied alpha blend for the object displaying the render texture. You can use the Particles/Alpha Blend Premultiply shader to test with, though that shader does more than you probably need or want.

 

Thank you so much! I can't believe it's that simple and I spent more than a day on it without results!