When camera stacking for HDRP?

sergiusz308 · March 18, 2020, 7:06pm

I am confused with this blog-post, regarding camera stacking:

it says URP already has camera stacking - great, really happy, but what about HDRP? When it’s planned to be released?

Thanks,
S.

Onigiri · March 18, 2020, 7:10pm

Yes its planned. They are making new compositor tool for this

sergiusz308 · March 18, 2020, 7:21pm

It’s planned for 2020.1 or later? As always, I understand that it’s done when it’s done, but anyway - which teach stream they’re planning it for?

Onigiri · March 18, 2020, 7:32pm

I don’t know when its will hit release. I suppose 2020.1 if everything will be ok. In the meanwhile you can test compositor branch from github https://github.com/Unity-Technologies/ScriptableRenderPipeline/tree/HDRP/compositor Last time i checked it was working and i successfully made object rendered always on top of a scene. I can even made different AA and postprocessing for different layers so this is even better than stacking from built-in renderer and urp.

ftejada · June 15, 2020, 4:48pm

Hi everyone!!!
Excuse my ignorance @Onigiri , but although I have read the description on github, it is not very clear to me what improvements this tool can bring to HDRP …
Performance improvements? for example when having two cameras at the same time in the scene? now it’s impossible to have them without totally killing performance …

I don’t know … what improvements does this tool provide?

Cheers

Cookieg82 · June 19, 2020, 8:49pm

Hey, Thanks for the link - it looks like it has been either removed or moved? The link is 404.

I wanted to give it a test ride. Guess the wait is on.

nsxdavid · July 17, 2020, 5:20am

HDRP 9.0 (preview.33) changelog contains the following note:

Added the HDRP Compositor Tool (in Preview).

And is documented here:

https://docs.unity3d.com/Packages/com.unity.render-pipelines.high-definition@9.0/manual/Compositor-Main.html

Plus, the first thing it says is it allows Camera Stacking.

So BOOYA! Maybe we’re back in business!

Velo222 · July 17, 2020, 11:59am

This is great, I think this is exactly what I needed too. Trying to make a minimap for one of my games render over the post-processing with two cameras in HDRP was not happening.

nsxdavid · July 17, 2020, 2:21pm

I played around with it today and found that it does work, though it is tricky. Here is a hint:

The compositor is like a camera and it has to be set to a specific display number (use 1).

And now your main camera, and in fact all cameras, have to be set to unique display numbers that are not 1.

So every camera is pointing to a different display number, say 2 and 3 and 4 depending on how many cameras you want to stack. Use 1, for example, to be the “display” for the compositor to output too.

Having said that, I have been unable to get this stacking to work correctly with the built in UI system (UGUI). You can get UI to render, but that’s just by directing it to the same output display. If you want something to render in front of UI (like say a 3D object “in” your UI) then things seem to fall apart and I can find no way to arrange all the pieces so that it works. I’m making a standalone test project to play with this more and see if it is a bug or not.

Velo222 · July 17, 2020, 4:35pm

nsxdavid:

I played around with it today and found that it does work, though it is tricky. Here is a hint:

The compositor is like a camera and it has to be set to a specific display number (use 1).

And now your main camera, and in fact all cameras, have to be set to unique display numbers that are not 1.

So every camera is pointing to a different display number, say 2 and 3 and 4 depending on how many cameras you want to stack. Use 1, for example, to be the “display” for the compositor to output too.

Having said that, I have been unable to get this stacking to work correctly with the built in UI system (UGUI). You can get UI to render, but that’s just by directing it to the same output display. If you want something to render in front of UI (like say a 3D object “in” your UI) then things seem to fall apart and I can find no way to arrange all the pieces so that it works. I’m making a standalone test project to play with this more and see if it is a bug or not.

Very interesting, thanks for sharing that. For my use-case all I need is for one camera that is rendering the post-processing effects to be displayed under another camera that is set to render the layer of a scene object (in the actual scene) above the post-processing camera, not on the GUI – fortunately.

So I think, from what you’re saying, it sounds like it might still work for me. I don’t need to render anything in front of the UI (yet). Again, thankfully. As I have not tested anything yet, this is all speculation lol.

I hope at some point HDRP catches up with the URP/Built-in pipelines in terms of features.

Great info, thank you

nsxdavid · July 18, 2020, 9:41pm

You said you have one camera rendering post-processing effects… I assume you have something in the scene that this camera renders right?

sergiusz308 · July 21, 2020, 11:03am

@nsxdavid Link to the docs seems to be broken?

nsxdavid · July 21, 2020, 2:14pm

Try: Getting started with the High Definition Render Pipeline | High Definition RP | 9.0.0-preview.71

Then find the compositor from there.

Camarent · July 21, 2020, 2:39pm

I did not find it in documentation by this link but here is the link from github: https://github.com/Unity-Technologies/Graphics/blob/f27cb5aeee8c080a2089e076b85749e8f6fd59a4/com.unity.render-pipelines.high-definition/Documentation~/Compositor-Main.md

nsxdavid · July 22, 2020, 4:33am

Yeah there is something strange going on with the docs. Even from that page, clicking User Guide is a bad link.

valarnur · July 22, 2020, 10:20am

Should compositor be used for UI if renders text on top of the screen?

SebLagarde · July 23, 2020, 11:46am

Hi, the main solution we recommend for UI is to use the after Postprocess Rendering pass on Material.
https://docs.unity3d.com/Packages/com.unity.render-pipelines.high-definition@9.0/manual/Surface-Type.html
And if you need some blur you can use custom pass after postprocess

Compositor is a super set of Camera stacking see Graphics/com.unity.render-pipelines.high-definition/Documentation~/Compositor-Main.md at f27cb5aeee8c080a2089e076b85749e8f6fd59a4 · Unity-Technologies/Graphics · GitHub

It should bring some performance compare to using 2 camera, however, the compositor tool primary target isn’t to do UI in game but to do compositing for non game application. Still if it fit into your frame budget you can use it.

Doc isn’t puslish yet but as pointed by others there is this:

github.com

Unity-Technologies/Graphics/blob/f27cb5aeee8c080a2089e076b85749e8f6fd59a4/com.unity.render-pipelines.high-definition/Documentation~/Compositor-User-Guide.md

# Using the Graphics Compositor
To open the Graphics Compositor window in the Unity Editor, select **Window > Render Pipeline > Graphics Compositor** from the menu. From this window, you can control the Graphics Compositor configuration. The first time you open the Graphics Compositor window, it automatically uses a default *"pass-through"* composition profile that forwards the output of the main [Camera](HDRP-Camera.md) to the final composed frame. You can edit this profile or you can load another one from disk. For information on the properties in the Compositor window, see [Compositor window](Compositor-User-Options.md).


## Layer Types
The Graphics Compositor tool typically handles two types of layers: 
- **Composition Layers**: Which you define in the [Composition Graph](#composition-graph). The Composition Graph defines the number of layers and how to combine them but does not define each layer's content.
- **Sub-layers**: Which you define in the Graphics Compositor window, in the [Render Schedule](#render-schedule) section. You use stack Sub-layers to define the content of a Composition Layer.


## Composition Graph
To specify the output image, the Graphics Compositor uses a graph of compositing operations. Specifically, the Graphics Compositor uses the [Shader Graph](https://docs.unity3d.com/Packages/com.unity.shadergraph@latest/index.html) with an [Unlit Master Node](https://docs.unity3d.com/Packages/com.unity.shadergraph@latest/index.html?subfolder=/manual/Unlit-Master-Node.html) as its target. To specify the output image, the Compositor uses the value you connect to the **Color** port. You do not need to connect any other ports on the Master Node.

**Note**: When the output of the composition is to a render target, the Material you create from the Master Node must be double-sided.

When you create a Composition Graph, there are two main types of input property you can expose:
- **Composition Layer**: Any **Texture2D** properties act as Composition Layers which correspond to a layer the graph composites to generate the final frame. These properties appear automatically as Composition Layers in the [Render Schedule](#render-schedule) section of the Graphics Compositor window. The **Mode** option for them in Shader Graph corresponds to the default value the Shader uses when you toggle off the visibility of the layer in the Render Schedule list.<br/> **Note**: By default, this value is set to white, but for many compositing operations and behaviors, you may want to set this to black instead.
- **Composition Parameters**: This refers to any exposed property that is not a Texture2D. Composition Parameters can control various aspects of the composition. Examples of Composition Parameters include a Vector1 input to control the overall brightness or a Color input to tint a Texture2D. These properties appear automatically in the [Composition Parameters](#composition-parameters) section of the Graphics Compositor window.

The following graph contains examples of the property types described above. The **Logo** property is an example of a Composition Layer and the **Opacity** property is an example of an input property to control an aspect of the composition:

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github.com

Unity-Technologies/Graphics/blob/f27cb5aeee8c080a2089e076b85749e8f6fd59a4/com.unity.render-pipelines.high-definition/Documentation~/Compositor-User-Options.md

# Graphics Compositor window
This page provides an outline of the options available in the Graphics Compositor window.

## Output Options
This section allows you to change where and how the Graphics Compositor outputs the final frame.

The Graphics Compositor can only output to the Game View. To preview the output while you edit the Scene, enable the **Enable Preview** property. **Tip**: To get the best live preview, undock the Game view window into a separate maximized window. If you have two monitors, you can drag the window to a second screen.

| **Property**           | **Description** |
| ----------------------  | --------------- |
| **Enable Compositor** | Specifies whether your Unity Project uses the Graphics Compositor. If you disable this property and the Scene did not previously use the Graphics Compositor, this is the only property visible in the window. If you disable this property and the Scene did previously use the Graphics Compositor, the rest of the properties appear in the window, but you can not edit them. |
| **Enable Preview**   | Specifies whether the Graphics Compositor always outputs to the Game view, even when you are not in Play Mode. If you disable this property, performance increases while you edit a Scene, but the Graphics Compositor output is only available in Play Mode. |
| **Output Camera**      | Specifies the Camera that the Graphics Compositor outputs to. You should use a dedicated Camera rather than re-use another Camera from your Scene. Also, make sure the Compositor's Camera targets a different Display to all other Cameras. This is important because, if the Compositor Camera uses the same display as another Camera, the Display output depends on which Camera Unity rendered last. |
| **Composition Graph** | Specifies the Shader that the Graphics Compositor uses to create the final output. When you first enable the Graphics Compositor for a Scene, this is a pass-through Shader Graph that passes a copy of the input to the output. To set up Camera stacking behavior, this kind of Shader is sufficient, but, for more complex compositing operations, define your own graph. For more details, see [Using the Compositor](Compositor-User-Guide.md). |
| **Display Output**    | Specifies the display that the Graphics Compositor renders to. Unity supports up to eight displays. To see the compositor output, click the **Display** drop-down in the upper left corner of the Game view and select the display number you specified here. |

## Composition Layer Properties

To expose these properties, select a Composition Layer in the **Render Schedule**.

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sergiusz308 · July 23, 2020, 10:28pm

Thanks for the update and summing it all up.

I don’t understand though this quote - what do you mean it’s not for game application? So, considering HDRP and XXI century we are all in right now (technology-wise), how I am supposed to achieve such a trivial and basic thing like first person view models rendering in Unity? As you know it has it’s own nuances, like need for a different fov, shadows resolution, etc. - is the only option is to write own post-processing / custom passes for this?

valarnur · July 23, 2020, 10:43pm

Even in HDRP you can render first person objects with second camera and render texture but it’s more performant to use ready custom pass https://github.com/alelievr/HDRP-Custom-Passes

SebLagarde · July 23, 2020, 11:11pm

Hi, you can check how FPS game is handled in this sample game: GitHub - Unity-Technologies/FPSSample: A first person multiplayer shooter example project in Unity (Was handled with Shader graph). Sadly the project is an on old revision of Unity and don’t convert to recent version.

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When camera stacking for HDRP?

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