Version: 2020.3
Language : English
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Single-Pass Stereo Rendering for Android

Single-pass stereo renderingThe process of drawing graphics to the screen (or to a render texture). By default, the main camera in Unity renders its view to the screen. More info
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is currently supported on Gear VRVirtual Reality More info
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and Daydream devices. To enable this feature we use the GL_OVR_multiview2 and GL_OVR_multiview_multisampled_render_to_texture OpenGL|ES extensions*. These extensions require the use of a texture 2D array with 2 slices (one slice per eye). This differs from our PC/PS4 implementation where we just use a double wide 2D texture. Therefore different shaderA program that runs on the GPU. More info
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changes are required.

Shader script requirements

You may need to include the additional code listed below to use Single-Pass Stereo Rendering with your custom shaders. This doesn’t apply to surface shadersA streamlined way of writing shaders for the Built-in Render Pipeline. More info
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or fixed function pipeline shaders which Unity automatically converts, except surface shaders that have custom vertex processing.

Note that these shader script changes are compatible with Multi-Pass stereo rendering, so there will be no side effects in that mode.

First, if you’d like to use unity_StereoEyeIndex in shader stages after 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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you must declare UNITY_VERTEX_OUTPUT_STEREO in any shader stage output structs that you have. Here’s an example:

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

Next, you must use UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO() in the vertex shader function to initialize the output data:

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

To initialize unity_StereoEyeIndex in subsequent stages you need to add UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX() at the beginning like so:

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

If you are using other shader stages you should also use the UNITY_TRANSFER_VERTEX_OUTPUT_STEREO()macro to transfer the eye index to the subsequent stages.

Finally, we recommend that you use UnityObjectToClipPos(IN.vertex) instead of mul(UNITY_MATRIX_MVP, IN.vertex) to calculate the final position of the object.

Post-Processing Shaders

Post-Processing shaders will need to be updated to deal with the eye textures being a texture 2D array. To help out with this we’ve created the following macro: UNITY_DECLARE_SCREENSPACE_TEXTURE(). This macro should be used to wrap all textures, so that the texture will work in both multi-pass and single-pass modes.

When sampling the texture the following macro should be used:

UNITY_SAMPLE_SCREENSPACE_TEXTURE()

This macro requires that UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX() has already been called beforehand when in single-pass mode. We’ve also created similar macros for depth textures and screen space shadow maps. You can see the full list at the bottom of HLSLSupport.cginc.

* These OpenGL|ES extensions are relatively new, so unfortunately there may be graphics related issues due to the drivers on these phones.


  • New feature in 5.5

  • 2017–06–20 Page published

Android symbols
Vulkan swapchain pre-rotation