Apply Bloom only to specific Materials

Help & Support
9

Thank you, @mvaligursky, for step-by-step instructions. What do you mean by setting a callback to camera on before UI gets rendered?

10

Thank you for your help. i could not find anything on how to blend the texture into the framebuffer. Do you have some example for that. for the callback i thought about using “uiLayer.onPreRender”.

11

Perhaps this callback on UI layer could be used.
https://developer.playcanvas.com/en/api/pc.Layer.html#onPreRender

Blend texture to framebuffer … this basically means to render full screen quad using the bloomed textured. As an example you can study post processing effects, such as bloom … they internally render multiple full screen passes for blurring the texture. So you’d need something similar.

And also I’ve relalized … if you only render few objects into the bloom texture and bloom that, it would not interact with the scene in cases something is rendered over the top. Example: you have a character you bloom, but in the scene its only half visible from behind a wall. This solution would bloom and make visible even hidden part of the character. To work around it, you’d need to do a depth pre-pass to your bloom texture - basically render the whole scene bit disable color rendering, and only write to the depth map. That would cause the character to be properly occluded.

Completely different way to approach it would be to use alpha channel of your render target to mask what needs to be bloomed. This way you would render the scene only one time, and during the opaque rendering, change the alpha output to mark meshes you want bloomed - for example character would output 1, everything else would output 0. Then at the end of opaque layers, you’d use this texture to apply bloom based on this alpha channel.

None of these are very easy to set up to be honest.

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12

I did manage to render the Bloom Layer to a Texture. for a test i render the result to a plane. The issue is after i enable bloom on the camera the rendering is empty.

here is a test scene:
https://playcanvas.com/editor/project/770478

13

Fixed the render issue, but on my rendered texture no bloom was applied.

14

have a l look at here Post Process doesn't work at logRenderActions and try it as well to get a log of what is happening. Perhaps post it here as well.

1 Like
15

Here is the result:

0 Cam: BloomCamera      Lay: Bloom            TRANSP ENABLED  Meshes:  0 RT: Untitled                  Clear: Color Depth Stencil CAM-FIRST
1 Cam: BloomCamera      Lay: Bloom            OPAQUE ENABLED  Meshes:  2 RT: Untitled                  Clear: ..... ..... ....... POSTPROCESS
2 Cam: Camera           Lay: World            OPAQUE ENABLED  Meshes:  2 RT: -                         Clear: Color Depth Stencil CAM-FIRST
3 Cam: Camera           Lay: Depth            OPAQUE DISABLED Meshes:  0 RT: -                         Clear: ..... ..... .......
4 Cam: Camera           Lay: Skybox           OPAQUE ENABLED  Meshes:  0 RT: -                         Clear: ..... ..... .......
5 Cam: Camera           Lay: World            TRANSP ENABLED  Meshes:  0 RT: -                         Clear: ..... ..... .......
6 Cam: Camera           Lay: Immediate        OPAQUE ENABLED  Meshes:  0 RT: -                         Clear: ..... ..... .......
7 Cam: Camera           Lay: Immediate        TRANSP ENABLED  Meshes:  0 RT: -                         Clear: ..... ..... ....... POSTPROCESS
16

can you show the whole thing? it’s cropped on the right side … and that’s where the render target and clearing stuff is displayed

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17

1232×186 40 KB

here is an screenshot of it. but i dont think that i missed anything

18

There is a scrollbar :wink:

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19

Ah … I thought it was part of the screenshot! :slight_smile:

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20

I’ll need to test it locally … hopefully in a few days.

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21

I’ve create an issue to get this fixed https://github.com/playcanvas/engine/issues/2941

22

Thanks a lot. looking forward to the fix. I also really appreciate all the support from the devs and the community.

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23

@mvaligursky Hi,thanks so much for your advice!It really helps!
I am trying to achieve this effect accroding to your sceond method,using alpha channel.But I am stuck at the correct way to mark the meshes to bloom,can you describe more precisely?How can I achieve that?

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24

This would also interesst me, it also sounds like an faster approach.

25

SpectorJS is your friend … you can capture the frame and inspect what is going on, including shaders.
You will most likely find that all shaders on opaque meshes output 1 in alpha channel … or maybe all 0, not sure, capture frame and look at the shader.

You need to modify shaders so that meshes you want bloomed output 1, and others output 0 (or grayscale depending on level of bloom).

At the moment bloom shader converts pixel into greyscale and if it’s brighter than some value it blooms it. You would instead read that alpha value from the texture to decide if it should bloom.

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26

sorry for being annoying but are there any plans for the this to get fixed soon ?

27

There’s been no progress on this yet unfortunately.

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28

@Sinlyu This was just merged:

This will be deployed as 1.40.5 - hopefully today or tomorrow.

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