LWRP XR Single-pass Instancing and Multi-view Support

Added support for single-pass instancing and multi-view support for XR with LWRP.

ScriptableRenderPipeline/Core/CoreRP/ShaderLibrary/UnityInstancing.hlsl

     #define UNITY_SUPPORT_INSTANCING
 #endif
 
-#if defined(SHADER_API_D3D11)
+#if defined(SHADER_API_D3D11) || defined(SHADER_API_GLCORE) || defined(SHADER_API_GLES3)
     #define UNITY_SUPPORT_STEREO_INSTANCING
 #endif
 
 // - UNITY_TRANSFER_VERTEX_OUTPUT_STEREO    Copy stero target from input struct to output struct. Used in vertex shader.
 // - UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX
 #ifdef UNITY_STEREO_INSTANCING_ENABLED
+#if defined(SHADER_API_GLES3) || defined(SHADER_API_GLCORE)
+    #define DEFAULT_UNITY_VERTEX_OUTPUT_STEREO                          uint stereoTargetEyeIndexSV : SV_RenderTargetArrayIndex; uint stereoTargetEyeIndex : BLENDINDICES0;
+    #define DEFAULT_UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(output)       output.stereoTargetEyeIndexSV = unity_StereoEyeIndex; output.stereoTargetEyeIndex = unity_StereoEyeIndex;
+#else
+#endif
     #define DEFAULT_UNITY_TRANSFER_VERTEX_OUTPUT_STEREO(input, output)  output.stereoTargetEyeIndex = input.stereoTargetEyeIndex;
     #define DEFAULT_UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(input) unity_StereoEyeIndex = input.stereoTargetEyeIndex;
 #elif defined(UNITY_STEREO_MULTIVIEW_ENABLED)
     void UnitySetupInstanceID(uint inputInstanceID)
     {
         #ifdef UNITY_STEREO_INSTANCING_ENABLED
-            // stereo eye index is automatically figured out from the instance ID
-            unity_StereoEyeIndex = inputInstanceID & 0x01;
-            unity_InstanceID = unity_BaseInstanceID + (inputInstanceID >> 1);
+            #if defined(SHADER_API_GLES3)
+                // We must calculate the stereo eye index differently for GLES3
+                // because otherwise,  the unity shader compiler will emit a bitfieldInsert function.
+                // bitfieldInsert requires support for glsl version 400 or later.  Therefore the
+                // generated glsl code will fail to compile on lower end devices.  By changing the
+                // way we calculate the stereo eye index,  we can help the shader compiler to avoid
+                // emitting the bitfieldInsert function and thereby increase the number of devices we
+                // can run stereo instancing on.
+                unity_StereoEyeIndex = round(fmod(inputInstanceID, 2.0));
+                unity_InstanceID = unity_BaseInstanceID + (inputInstanceID >> 1);
+            #else
+                // stereo eye index is automatically figured out from the instance ID
+                unity_StereoEyeIndex = inputInstanceID & 0x01;
+                unity_InstanceID = unity_BaseInstanceID + (inputInstanceID >> 1);
+            #endif
         #else
             unity_InstanceID = inputInstanceID + unity_BaseInstanceID;
         #endif

ScriptableRenderPipeline/LightweightPipeline/LWRP/LightweightPipeline.cs

             }
 
             SetRenderTarget(cmd, colorRT, depthRT, clearFlag);
+            m_CurrCameraColorRT = colorRT;
 
             // If rendering to an intermediate RT we resolve viewport on blit due to offset not being supported
             // while rendering to a RT.

ScriptableRenderPipeline/LightweightPipeline/LWRP/ShaderLibrary/InputBuiltin.hlsl

 #ifndef LIGHTWEIGHT_SHADER_VARIABLES_INCLUDED
 #define LIGHTWEIGHT_SHADER_VARIABLES_INCLUDED
 
-#if (defined(SHADER_API_D3D11)  || defined(SHADER_API_PSSL)) && defined(STEREO_INSTANCING_ON)
+#if defined(STEREO_INSTANCING_ON) && (defined(SHADER_API_D3D11) || defined(SHADER_API_GLES3) || defined(SHADER_API_GLCORE) || defined(SHADER_API_PSSL))
+#endif
+
+#if defined(STEREO_MULTIVIEW_ON) && (defined(SHADER_API_GLES3) || defined(SHADER_API_GLCORE)) && !(defined(SHADER_API_SWITCH))
+    #define UNITY_STEREO_MULTIVIEW_ENABLED
 #endif
 
 #if defined(UNITY_SINGLE_PASS_STEREO) || defined(UNITY_STEREO_INSTANCING_ENABLED) || defined(UNITY_STEREO_MULTIVIEW_ENABLED)
 
 CBUFFER_END
 
+#if defined(UNITY_STEREO_MULTIVIEW_ENABLED) || ((defined(UNITY_SINGLE_PASS_STEREO) || defined(UNITY_STEREO_INSTANCING_ENABLED)) && (defined(SHADER_API_GLCORE) || defined(SHADER_API_GLES3) || defined(SHADER_API_METAL)))
+    #define GLOBAL_CBUFFER_START(name)    cbuffer name {
+    #define GLOBAL_CBUFFER_END            }
+#else
+    #define GLOBAL_CBUFFER_START(name)    CBUFFER_START(name)
+    #define GLOBAL_CBUFFER_END            CBUFFER_END
+#endif
+
-CBUFFER_START(UnityStereoGlobals)
+GLOBAL_CBUFFER_START(UnityStereoGlobals)
 float4x4 unity_StereoMatrixP[2];
 float4x4 unity_StereoMatrixV[2];
 float4x4 unity_StereoMatrixInvV[2];
 
 float3 unity_StereoWorldSpaceCameraPos[2];
 float4 unity_StereoScaleOffset[2];
-CBUFFER_END
+GLOBAL_CBUFFER_END
-CBUFFER_START(UnityStereoEyeIndices)
-real4 unity_StereoEyeIndices[2];
-CBUFFER_END
+GLOBAL_CBUFFER_START(UnityStereoEyeIndices)
+    float4 unity_StereoEyeIndices[2];
+GLOBAL_CBUFFER_END
+#endif
+
+#if defined(UNITY_STEREO_MULTIVIEW_ENABLED) && defined(SHADER_STAGE_VERTEX)
+// OVR_multiview
+// In order to convey this info over the DX compiler, we wrap it into a cbuffer.
+#if !defined(UNITY_DECLARE_MULTIVIEW)
+#define UNITY_DECLARE_MULTIVIEW(number_of_views) GLOBAL_CBUFFER_START(OVR_multiview) uint gl_ViewID; uint numViews_##number_of_views; GLOBAL_CBUFFER_END
+#define UNITY_VIEWID gl_ViewID
+#endif
 #endif
 
 #if defined(UNITY_STEREO_MULTIVIEW_ENABLED) && defined(SHADER_STAGE_VERTEX)
 static uint unity_StereoEyeIndex;
 #elif defined(UNITY_SINGLE_PASS_STEREO)
-CBUFFER_START(UnityStereoEyeIndex)
+GLOBAL_CBUFFER_START(UnityStereoEyeIndex)
-CBUFFER_END
+GLOBAL_CBUFFER_END
 #endif
 
 CBUFFER_START(UnityPerDrawRare)

ScriptableRenderPipeline/LightweightPipeline/LWRP/ShaderLibrary/LightweightPassDepthOnly.hlsl

 {
     float2 uv           : TEXCOORD0;
     float4 clipPos      : SV_POSITION;
+    UNITY_VERTEX_INPUT_INSTANCE_ID
+    UNITY_VERTEX_OUTPUT_STEREO
 };
 
 VertexOutput DepthOnlyVertex(VertexInput v)
+    UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
 
     o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);
     o.clipPos = TransformObjectToHClip(v.position.xyz);

ScriptableRenderPipeline/LightweightPipeline/LWRP/Shaders/LightweightSampling.shader

     {
         float4 vertex   : POSITION;
         float2 texcoord : TEXCOORD0;
+        UNITY_VERTEX_INPUT_INSTANCE_ID
     };
 
     struct Interpolators
+        UNITY_VERTEX_INPUT_INSTANCE_ID
     };
 
     Interpolators Vertex(VertexInput i)

ScriptableRenderPipeline/LightweightPipeline/LWRP/Shaders/LightweightScreenSpaceShadows.shader

         half4 Fragment(Interpolators i) : SV_Target
         {
             UNITY_SETUP_INSTANCE_ID(i);
-#if !defined(UNITY_STEREO_INSTANCING_ENABLED)
-            // Completely unclear why i.stereoTargetEyeIndex doesn't work here, considering
-            // this has to be correct in order for the texture array slices to be rasterized to
-            // We can limit this workaround to stereo instancing for now.
-#endif
 
 #if defined(UNITY_STEREO_INSTANCING_ENABLED) || defined(UNITY_STEREO_MULTIVIEW_ENABLED)
             float deviceDepth = SAMPLE_TEXTURE2D_ARRAY(_CameraDepthTexture, sampler_CameraDepthTexture, i.texcoord.xy, unity_StereoEyeIndex).r;