Rendering virtual objects transparent in augmented reality

Question

I want to place virtual objects in my augmented reality scene which are rendered transparent.

For sake of simplicity, let's take Googles SimpleAugmentedReality Scene. When you just take the scene as it comes from the example project, an earth and a moon are placed in front of you, rendered opaque with a texture.

When I change the materials "Rendering Mode" to "Transparent" I expect them to become transparent but nothing changes.

I also tried custom shaders in which I rendered just a cube and set the alpha value below 1.0. It is also drawn opaque in the AR scene.

Do I miss some configuration in Tango Camera prefab?

Answer 1

This is not supported in TangoSDK now, but I think it's a very reasonable ask.

The reason it's not working is because TangoSDK inject the background camera render command into Unity's command buffer, and rendered with glDepthMask(GL_FALSE);

This will cause alpha blending to not to take in the color from background camera render.

Answer 2

Actually it works now: I was not familiar with shaders in Unity, so I forgot the Tags{"Queue" = "Transparent"} tag within the sub shader. Also, the Blend SrcAlpha OneMinusSrcAlpha directive was not set within the pass.

Now my objects are rendered transparent "on top" of the RGB camera video frame depending on the alpha value defined in the shader.