[HDRP] Backport various PRs (#7232)

* Improve Path tracing docs #6494

* [HDRP] Improves robustness of detail normal mapping when scale = 0 (and not using surface gradients) #6980

* Add pragma renderer only for planar reflection preview shader (#7058)

* Add pragma renderer only for planar reflection preview shader

* various missing part

* Fix wrong class name in the CustomPassUtils doc (#7063)

* Fix null check reference in CollectLightsForRayTracing (Fix 1398381) #7065

* Fixed camera motion vector pass reading last frame depth texture #7111

* Update Custom-Pass-Injection-Points.md (#7116)

* Update Custom-Pass-Injection-Points.md (#7116)

* Fix lunix compil issues (#7143)

* note bolding (#7161)

* note bolding

* Apply formatting changes

* Update blit-overview.md

* Update blit-overview.md

* Update blit-overview.md

* Update blit-overview.md

* Update blit-overview.md

* Update blit-overview.md

Co-authored-by: noreply@unity3d.com <noreply@unity3d.com>
Co-authored-by: sebastienlagarde <sebastien@unity3d.com>

* updated screenshots (#7164)

* updated screenshots

* Apply formatting changes

Co-authored-by: noreply@unity3d.com <noreply@unity3d.com>

Co-authored-by: Vic Cooper <63712500+Vic-Cooper@users.noreply.github.com>
Co-authored-by: Emmanuel Turquin <emmanuel@turquin.org>
Co-authored-by: Antoine Lelievre <antoinel@unity3d.com>
Co-authored-by: JulienIgnace-Unity <julien@unity3d.com>
Co-authored-by: emilybrown1 <88374601+emilybrown1@users.noreply.github.com>
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Author: 7 people

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -6,8 +6,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [12.1.6] - 2022-02-09
 
-Version Updated
-The version number for this package has increased due to a version update of a related graphics package.
+### Fixed
+- Fixed issue with detail normals when scale is null (case 1399548).
+- Fixed null reference issue in CollectLightsForRayTracing (case 1398381)
+- Fixed camera motion vector pass reading last frame depth texture
 
 ## [12.1.5] - 2022-01-14
 
@@ -48,6 +50,7 @@ The version number for this package has increased due to a version update of a r
 - Fixed various issues with render graph viewer when entering playmode.
 - Fixed issue with Final Image Histogram displaying a flat histogram on certain GPUs and APIs.
 - Fixed HDRP camera debug panel rendering foldout.
+- Fixed issue with detail normals when scale is null (case 1399548).
 
 ## [12.1.4] - 2021-12-07
 

com.unity.render-pipelines.high-definition/Documentation~/Custom-Pass-Injection-Points.md

@@ -15,7 +15,7 @@ Unity triggers the following injection points in a frame, in order from top to b
 | **Injection point**       | **Available buffers**                                        | **Description**                                              |
 | ------------------------- | ------------------------------------------------------------ | ------------------------------------------------------------ |
 | BeforeRendering           | Depth (Write)                                                | Unity clears the depth buffer immediately before this injection point. <br/><br/>In this injection point you can write to the depth buffer so that Unity doesn’t render depth-tested, opaque objects.<br/><br/>You can also clear the buffer you allocated or the `Custom Buffer`.<br/><br/>When you select this Injection point for a [FullscreenCustom Pass](Custom-Pass-Creating.md#Full-Screen-Custom-Pass), Unity assigns the camera color buffer as the target by default. |
-| AfterOpaqueDepthAndNormal | Depth (Read \| Write), Normal and roughness (Read \| Write), Motion Vectors (Read \| Write) | The available buffers for this injection point contain all opaque objects.<br/><br/>In this injection point you can modify the normal, roughness, depth, and motion vectors buffers. HDRP takes this into account in the lighting and the depth pyramid.<br/><br/>Normals and roughness are in the same buffer. You can use `DecodeFromNormalBuffer` and `EncodeIntoNormalBuffer` methods to read/write normal and roughness data. <br/><br/>The Motion Vectors buffer only includes object motion vector data when you use [forward rendering](Forward-And-Deferred-Rendering.md). To include object motion vector data in the Motion Vectors buffer when using deferred rendering, go to [Frame Settings](Frame-Settings.md) and enable **Depth Prepass within Deferred**. |
+| AfterOpaqueDepthAndNormal | Depth (Read \| Write), Normal and roughness (Read \| Write), Motion Vectors (Write) | The available buffers for this injection point contain all opaque objects.<br/><br/>In this injection point you can modify the normal, roughness, depth, and motion vectors buffers. HDRP takes this into account in the lighting and the depth pyramid.<br/><br/>Normals and roughness are in the same buffer. You can use `DecodeFromNormalBuffer` and `EncodeIntoNormalBuffer` methods to read/write normal and roughness data. <br/><br/>The Motion Vectors buffer only includes object motion vector data when you use [forward rendering](Forward-And-Deferred-Rendering.md). To include object motion vector data in the Motion Vectors buffer when using deferred rendering, go to [Frame Settings](Frame-Settings.md) and enable **Depth Prepass within Deferred**. |
 | BeforePreRefraction       | Color (no pyramid \| Read \| Write), Depth (Read \| Write), Normal and roughness (Read), Motion Vectors (Read \| Write) | The available buffers for this injection point contain all opaque objects, the camera and object motion vectors, and the sky.<br/><br/> From this point, the motion vectors buffer is complete.<br/><br/>In this injection point you can render any transparent objects that require refraction. These objects are then included in the color pyramid that Unity uses for refraction when it renders transparent objects. |
 | BeforeTransparent         | Color (Pyramid \| Read \| Write), Depth (Read \| Write), Normal and roughness (Read), Motion Vectors (Read) | The available buffers for this injection point contain:<br/>- All opaque objects.<br/>- Transparent PreRefraction objects.<br/>- Transparent objects with depth-prepass and screen space reflections (SSR) enabled.<br/><br/>In this Injection Point you can sample the color pyramid that Unity uses for transparent refraction. You can use this to create a blur effect. All objects Unity renders in this injection point will not be in the color pyramid.<br/><br/>You can also use this injection point to draw some transparent objects that refract the whole scene, like water. |
 | BeforePostProcess         | Color (Pyramid \| Read \| Write), Depth (Read \| Write), Normal and roughness (Read), Motion Vectors (Read) | The available buffers for this injection point contain all geometry in the frame that uses High Dynamic Range (HDR). |