Godot: Viewport [3D in 2D] enable "Transparent Background" disables 3D scene WorldEnviroment/Reflections/Metallic/Specular and leaving the Background turns WorldEnviroment upsidedown

[rubenjavier]

Operating system or device, Godot version, GPU Model and driver (if graphics related):
Ubuntu 16.04 64 bits
Godot 3.0 commit d938de67fff288bf7f0a92fd51a2e890a1b5f245
IntelGPU

Issue description:
In a 2D scene, adding a Viewport to show a 3D scene and activating the Viewport "Transparent Bg" checkbox, disables the embeded 3D scene "WorldEnviroment" and this removes all the reflections/specular/metallic effects of the embedded scene, it doesnt matter if its its "Own World" or another created on the Viewport

Steps to reproduce:
Create a 2D Scene, reproducing the 3D in 2D godot demo and set it a as default scene
Create a 3D Scene with a MeshInstance (capsule, sphere) with a SpatialMaterial (I have used the textures from https://freepbr.com to create a metal)
Creata a Directional Light on the 3D Scene
Create a WorldEnviroment on the 3D scene
Create a Procedural Sky on the WorldEnviroment (the mesh will reflect the sky)
Go back to the main 2D Scene and enable "Transparent Bg" on the Viewport showing the 3D Scene, the world reflections will dissapear when you play the project
Disable the "Transparent Bg" on the Viewport, the world reflections will return but turned upsidedown

[rubenjavier]

Added a Demo Project so you can check the bug.
.-Open the project
.-Compile, see the viewport showing the 3D scene with the WorldEnviroment upsidedown
.-Enable "Transparent Bg" on the Viewport
.-Compile, see the viewport showing the 3D scene without any WorldEnviroment

3Din2D.zip

[rubenjavier]

@Noshyaar
Im attaching pictures of the bug showed in the demo for easier understanding

As you can see wih the "Transparent Bg" disabled, the WorldEnviroment shows upsidedown
and with the "Transparent Bg" enabled, there is no WorldEnviroment or reflections at all

[rubenjavier]

Maybe this is related?
https://github.com/godotengine/godot/issues/10250
https://github.com/godotengine/godot/issues/11935
since all specularity is lost from the WorldEnviroment when the "Transparent Bg" option is enabled
...Thanks

[bojidar-bg]

About the upside-down problem, you can check/uncheck the VFlip option on the Viewport.

[rubenjavier]

@bojidar-bg
Thanks, but the VFlip is not enabled, and after enabling it, the Viewport is still upsidedown, in other words, no matter the VFlip state, the Viewport is always upsidedown

[NathanWarden]

I can confirm that vflip doesn't work.

VFlip Off

VFlip On:

[hi-ogawa]

Regarding viewport vflip option, it looks like this PR https://github.com/godotengine/godot/pull/11067 is fixing it.

[rubenjavier]

@NathanWarden
I see the WorldEnviroment is also upsidedown in your 3D with Viewports.
Can you check if "Transparent Bg" also makes the WorldEnviroment disappear (with the specularity / reflections) from the viewport?

[NathanWarden]

It looks like vflip is working properly now :)

@rubenjavier Yes, it turns black and vflip is the opposite of what it is supposed to be. IE. when vflip is off it's upside down, but when it's turned on it's how it ought to be when it's off.

[kosz78]

Confirm that WorldEnvironment not work with Transparent Bg enabled in the latest master build

[akien-mga]

Is this still reproducible in the current master branch?

[NathanWarden]

@akien-mga I'll try and take a look and see if this is still a problem in an hour or two.

[NathanWarden]

So, this issue is actually two bugs... one fixed, one not.

The first bug persists. When turning on "Transparent Bg" the objects go black.

I think the second part is fixed. It now comes in upside down regardless of whether "Transparent Bg" is toggled or not. I personally think it being upside down is fine I think as long as it's consistent since vflip does turn it right-side up again.

Vflip works as expected, both are with vflip on:

I've seen this upside-downness in other engines so perhaps upside down is the default behavior when grabbing the render buffer? But, if being upside down is the default behavior for a viewport node then perhaps vflip should be defaulted to on?

[AndreaCatania]

@NathanWarden I've just tested it and it works fine now, probably you forgot to add directional light. Can you please check it?

[NathanWarden]

Adding a light does add lighting, but the environment lighting doesn't apply at all. Shouldn't "Transparent Bg" just "cut out" the background? Instead it's not allowing the environment lighting/shading to apply. I'd still consider this a bug.

I'm not a rendering expert, but it seems possible to have environment lighting/shading apply to objects, but not render the environment itself as the background, right?

[rubenjavier]

@NathanWarden and @AndreaCatania , exactly, the lightning behaviour hasn't changed and I still consider this a bug, the environment lightning/shading its lost while directional light is not.
I understand that the new engine uses the environment to calculate part of the light wich is great and looks awesome, but not rendering it visible on the viewport shouldnt necessarily affect the calculation since it could still be rendered in a buffer, or am I mistaken?

[akien-mga]

After discussing with @reduz, we're moving this issue to 3.1 so as not to take unnecessary risks to introduce regressions fixing it.

[kane-thornwyrd]

I'm sad to let you know that there is a regression concerning this in the 3.1.1 and on master.
All the shader effects like: reflections, blur, DoF, bloom, etc. does not work in a viewport with the Transparent bg option turned On. @rubenjavier @akien-mga sorry :/

[bojidar-bg]

Can confirm the same on v3.2.dev.custom_build. 7e108da07. Reopening..

[clayjohn]

It appears intentional that the post-process settings do not apply when a transparent background is used.

https://github.com/godotengine/godot/blob/813c0d84740b1d1c8ccece3540e945d1e821561d/drivers/gles3/rasterizer_scene_gles3.cpp#L3671-L3672

[Zireael07]

@clayjohn: In that case, it would be worth putting a warning in editor for that case (I was fooling around with layering two viewports yesterday and was about to post an issue...)

[clayjohn]

@Zireael07 Just because it appears intentional, doesn't mean we can't make it work! I'm not certain that it is impossible to get post-process settings to work with a transparent background. So I think we should attempt to improve this behaviour before putting in a warning/documentation

Also, I think this should be in its own issue. Post-processing settings are not related to displaying environment reflections. This is not a regression from the above issue, it is an issue in itself.

[akien-mga]

I just read through this issue and I think different bugs have been mentioned, some of which are fixed. The test project in OP works fine in the current master branch, you can enable v_flip on the Sprite to get the Viewport upright, and "Transparent Bg" seems functional:

So I'll close this. If there are some issues discussed here which are still not fixed, I would suggest opening new bug reports against the master branch with their own reproduction projects.