Move motion rendering order back to after opaques.

Fix Motion Vector render pass render order. Motion Vector pass depends on the Copy Depth pass. Copy Depth pass is moveable (from UniversalRenderer). Motion Vector pass order now correctly follows the Copy Depth pass. 
Motion Vectors can now be rendered after Opaques, instead of always rendering after Transparents.

Author: eh-unity

Packages/com.unity.render-pipelines.universal/Runtime/Passes/MotionVectorRenderPass.cs

@@ -26,9 +26,9 @@ sealed class MotionVectorRenderPass : ScriptableRenderPass
         #endregion
 
         #region Constructors
-        internal MotionVectorRenderPass(Material cameraMaterial)
+        internal MotionVectorRenderPass(RenderPassEvent evt, Material cameraMaterial)
         {
-            renderPassEvent = RenderPassEvent.BeforeRenderingPostProcessing;
+            renderPassEvent = evt;
             m_CameraMaterial = cameraMaterial;
             m_PassData = new PassData();
             base.profilingSampler = ProfilingSampler.Get(URPProfileId.MotionVectors);

Packages/com.unity.render-pipelines.universal/Runtime/UniversalRenderer.cs

@@ -270,7 +270,6 @@ public UniversalRenderer(UniversalRendererData data) : base(data)
 #endif
             m_DepthPrepass = new DepthOnlyPass(RenderPassEvent.BeforeRenderingPrePasses, RenderQueueRange.opaque, data.opaqueLayerMask);
             m_DepthNormalPrepass = new DepthNormalOnlyPass(RenderPassEvent.BeforeRenderingPrePasses, RenderQueueRange.opaque, data.opaqueLayerMask);
-            m_MotionVectorPass = new MotionVectorRenderPass(m_CameraMotionVecMaterial);
 
             if (renderingModeRequested == RenderingMode.Forward || renderingModeRequested == RenderingMode.ForwardPlus)
             {
@@ -312,13 +311,17 @@ public UniversalRenderer(UniversalRendererData data) : base(data)
             m_RenderOpaqueForwardWithRenderingLayersPass = new DrawObjectsWithRenderingLayersPass(URPProfileId.DrawOpaqueObjects, true, RenderPassEvent.BeforeRenderingOpaques, RenderQueueRange.opaque, data.opaqueLayerMask, m_DefaultStencilState, stencilData.stencilReference);
 
             bool copyDepthAfterTransparents = m_CopyDepthMode == CopyDepthMode.AfterTransparents;
+            RenderPassEvent copyDepthEvent = copyDepthAfterTransparents ? RenderPassEvent.AfterRenderingTransparents : RenderPassEvent.AfterRenderingSkybox;
 
             m_CopyDepthPass = new CopyDepthPass(
-                copyDepthAfterTransparents ? RenderPassEvent.AfterRenderingTransparents : RenderPassEvent.AfterRenderingSkybox,
+                copyDepthEvent,
                 copyDephPS,
                 shouldClear: true,
                 copyResolvedDepth: RenderingUtils.MultisampleDepthResolveSupported() && copyDepthAfterTransparents);
 
+            // Motion vectors depend on the (copy) depth texture. Depth is reprojected to calculate motion vectors.
+            m_MotionVectorPass = new MotionVectorRenderPass(copyDepthEvent + 1, m_CameraMotionVecMaterial);
+
             m_DrawSkyboxPass = new DrawSkyboxPass(RenderPassEvent.BeforeRenderingSkybox);
             m_CopyColorPass = new CopyColorPass(RenderPassEvent.AfterRenderingSkybox, m_SamplingMaterial, m_BlitMaterial);
 #if ADAPTIVE_PERFORMANCE_2_1_0_OR_NEWER
@@ -1700,7 +1703,11 @@ private RenderPassInputSummary GetRenderPassInputs(bool isTemporalAAEnabled, boo
 
             // Motion vectors imply depth
             if (inputSummary.requiresMotionVectors)
+            {
                 inputSummary.requiresDepthTexture = true;
+                inputSummary.requiresDepthTextureEarliestEvent = (RenderPassEvent)Mathf.Min((int)m_MotionVectorPass.renderPassEvent, (int)inputSummary.requiresDepthTextureEarliestEvent);
+            }
+
 
             return inputSummary;
         }

Packages/com.unity.render-pipelines.universal/Runtime/UniversalRendererRenderGraph.cs

@@ -1148,6 +1148,10 @@ private void OnMainRendering(RenderGraph renderGraph, ScriptableRenderContext co
                 m_CopyDepthPass.Render(renderGraph, frameData, cameraDepthTexture, resourceData.activeDepthTexture, true);
             }
 
+            // Depends on the camera (copy) depth texture. Depth is reprojected to calculate motion vectors.
+            if (renderPassInputs.requiresMotionVectors && m_CopyDepthMode != CopyDepthMode.AfterTransparents)
+                m_MotionVectorPass.Render(renderGraph, frameData, resourceData.cameraDepthTexture, resourceData.motionVectorColor, resourceData.motionVectorDepth);
+
             RecordCustomRenderGraphPasses(renderGraph, RenderPassEvent.BeforeRenderingSkybox);
 
             if (cameraData.camera.clearFlags == CameraClearFlags.Skybox && cameraData.renderType != CameraRenderType.Overlay)
@@ -1200,8 +1204,8 @@ private void OnMainRendering(RenderGraph renderGraph, ScriptableRenderContext co
             // TODO: Postprocess pass should be able configure its render pass inputs per camera per frame (settings) BEFORE building any of the graph
             // TODO: Alternatively we could always build the graph (a potential graph) and cull away unused passes if "record + cull" is fast enough.
             // TODO: Currently we just override "requiresMotionVectors" for TAA in GetRenderPassInputs()
-            // Depends on camera depth
-            if (renderPassInputs.requiresMotionVectors)
+            // Depends on camera (copy) depth texture
+            if (renderPassInputs.requiresMotionVectors && m_CopyDepthMode == CopyDepthMode.AfterTransparents)
                 m_MotionVectorPass.Render(renderGraph, frameData, resourceData.cameraDepthTexture, resourceData.motionVectorColor, resourceData.motionVectorDepth);
 
             if (context.HasInvokeOnRenderObjectCallbacks())