Version: 2022.3
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Single-pass stereo rendering for Android

Unity supports single-pass stereo rendering for Android devices that support multiview. Multiview consists of the GL_OVR_multiview2 and GL_OVR_multiview_multisampled_render_to_texture OpenGL ES extensions. These extensions require shadersA program that runs on the GPU. More info
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to use a 2D texture array that consists of two slices, one slice per eye.

Shader code requirements

To use single-pass stereo rendering with custom shaders, you may need to include additional shader code. You don’t need to include additional code if your custom shaders are:

  • Surface ShadersA streamlined way of writing shaders for the Built-in Render Pipeline. More info
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    that don’t have custom vertex processing.
  • Fixed-function pipeline shaders.

Note: These shader changes are compatible with multi-pass stereo rendering.

Modify your shaders

If you want to use the unity_StereoEyeIndex built-in shader variable to know which eye the GPU is rendering to, you must declare UNITY_VERTEX_OUTPUT_STEREO in any shader stage output structs that you have. For example:

struct v2f {
    float2 uv : TEXCOOR0;
    float4 vertex : SV_POSITION;

To initialize the output data, use UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO() in the vertex shaderA program that runs on each vertex of a 3D model when the model is being rendered. More info
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function. For example:

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

To initialize unity_StereoEyeIndex in subsequent stages, add UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX() at the beginning. For example:

fixed4 frag (v2f i) : SV_Target
    // sample the texture
    fixed4 col = tex2D(_MainTex, i.uv);
    // apply fog
    UNITY_APPLY_FOG(i.fogCoord, col);
    return col;

If your shaders use other shader stages, use the UNITY_TRANSFER_VERTEX_OUTPUT_STEREO() macro to transfer the eye index to the subsequent stages.

Tip: To calculate the final position of the object, it’s best practice to use UnityObjectToClipPos(IN.vertex) instead of mul(UNITY_MATRIX_MVP, IN.vertex).

Post-Processing Shaders

You must update post-processingA process that improves product visuals by applying filters and effects before the image appears on screen. You can use post-processing effects to simulate physical camera and film properties, for example Bloom and Depth of Field. More info post processing, postprocessing, postprocess
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shaders to deal with the eye textures being a 2D texture array. To help with this, Unity includes the UNITY_DECLARE_SCREENSPACE_TEXTURE() macro. To make textures work in both multi-pass and single-pass modes, wrap each textures in this macro. Also, when you sample the texture, use the UNITY_SAMPLE_SCREENSPACE_TEXTURE() macro.

This macro requires that you call UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX() beforehand when in single-pass mode. Unity also includes similar macros for depth textures and screen space shadow maps. You can see the full list at the bottom of HLSLSupport.cginc.

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