Passthrough Window Tutorial

• Create a new scene containing just the Directional Light and OVRCameraRig.
• Create a large solid plane to use as a backdrop.
• Create a smaller plane in front of the larger one that will allow the passthrough.
• Create a shader that will define how the colors in the passthrough are rendered, based on the scene lighting. (Refer to Materials, Shaders, and Textures in the Unity documentation.)
• Create a material for attaching the shader.
• Create a short script that will set the OVRManager.eyeFovPremultipliedAlphaModeEnabled property to false, and assign the script to the OVRCameraRig.

1. In the Project tab, under the Assets folder, create a new folder named Passthrough Tutorial, and then select it to make it the current folder for new objects.
2. In the Project Hierarchy, right click SampleScene, and choose Save Scene As. Give the new scene a unique name, such as PWScene. This becomes the active scene in the Hierarchy.
3. Remove any game objects from the scene, except for the Directional Light and OVRCameraRig.

1. On the top menu, go to GameObject > 3D Object > Plane, and name it SolidPlane.
2. Set Position to 10, 0, 10.
3. Set Scale to 20, 1, 20. This will cause it to fill the view at runtime.
4. Set Rotation to 0, 90, -90 so that the plane faces the OVRCameraRig view.
5. Drag the BallMaterial you used in the basic tutorial to SolidPlane.

1. On the top menu, go to GameObject > 3D Object > Plane. Name it PassthroughPlane.
2. Set Position to 10, 0, 5. This will place PassthroughPlane in front of SolidPlane.
3. Set Scale to 1, 1, 1. This makes it smaller than SolidPlane.
4. Set Rotation to 0, 90, -90 so that the plane faces the OVRCameraRig view.

1. On the top menu, go to Assets > Create > Shader > Unlit Shader, and name it PassthroughPlaneShader.
2. Double-click the PassthroughPlaneShader to open it in your code editor.
3. Immediately above CGPROGRAM add

      BlendOp RevSub
      Blend One Zero, Zero Zero
   
4. Adjust struct v2f to remove UNITY_FOG_COORDS(1):

   struct v2f
   {
      float2 uv : TEXCOORD0;
      // UNITY_FOG_COORDS(1) // delete or comment
      float4 vertex : SV_POSITION;
   };
   
5. Adjust struct v2f_vert to remove UNITY_TRANSFER_FOG(o,o.vertex);:

   v2f vert (appdata v)
   {
      v2f o;
      o.vertex = UnityObjectToClipPos(v.vertex);
      o.uv = TRANSFORM_TEX(v.uv, _MainTex);
      // UNITY_TRANSFER_FOG(o,o.vertex); // delete or comment
      return o;
   }
   
6. Adjust fixed4 frag (v2f i) so that it just returns the float4:

     fixed4 frag (v2f i) : SV_Target
      {
         return float4(0, 0, 0, 0);
      }
   
7. Save the file.

1. On the top menu, go to Assets > Create > Material, and name it PassthroughShaderMaterial.
2. Click PassthroughShaderMaterial to select it. Then, in the Inspector, set the Shader property to PassthroughPlaneShader.
3. In the Project pane, drag the PassthroughShaderMaterial to the PassthroughPlane.

1. On the top menu, go to Assets > Create > C# Script, and name it PassthroughPlaneScript.
2. Double-click the new script to open it.
3. Adjust the Start script as follows:

      void Start()
      {
   #if UNITY_EDITOR_WIN || UNITY_STANDALONE_WIN || UNITY_ANDROID
         OVRManager.eyeFovPremultipliedAlphaModeEnabled = false;
   #endif
       }
   
4. Save the script.

1. In the Hierarchy window, click OvrCameraRig.
2. In the Inspector, scroll to the bottom and choose Add Component.
3. Search for the PassthroughPlaneScript and add it.

1. On the top menu, go to File > Save, and then go to File > Save Project.
2. On the top menu, go to File > Build Settings to open the settings window.
3. Remove the previous scenes from the Scenes in Build pane. Then click Add Open Scenes.
4. Make sure that the Run Device is set to Meta Quest headset that is connected via USB cable.
5. Click Build and Run.
6. Save the .APK file.
7. Put on the headset to test the passthrough window. You should see a small window of passthrough surrounded by a larger opaque field.
   

Shader "Unlit/PassthroughTutorialShader"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        Pass
        {
           BlendOp RevSub
           Blend One Zero, Zero Zero

            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            sampler2D _MainTex;
            float4 _MainTex_ST;

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                return float4(0, 0, 0, 0);
            }
            ENDCG
        }
    }
}