pmndrs / pmndrs/react-postprocessing

[Bug] - N8AO works incorrectly with adaptiveDpr

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Description

Hey everyone! I seems found a bug in N8AO related to AdaptiveDpr

We found a strange effect in our application after adding N8AO to EffectComposer - sometimes it started to add weird 'reflections' to the materials, and we couldn't understand where it's coming from

image

This is how it looks like: On the surface of the model you can see "reflection" from grid, which should't be present (but it's not only about grid but any objects can appear as reflection).

After debugging for a while I've noticed that this happens on my machine when DPR value is changed. If we (or system) change dpr from 2 to 1, N8AO started to add this 'reflections'. As I can see class has size values which are half of the initial renderer size (if I understand correctly)

Снимок экрана 2024-04-23 в 10 16 47

If I manually call setSize(width, height) method on N8AOPostPass instance and upscale this values back to dpr=2 values this bug disappears. So it's either should always keep initial values or there is some error in calculation after updating render size

Steps to reproduce
Lest say screen size is 1000x500 with dpr=2. initial values of renderer is 2000x1000px, dpr=2, we set dpr to 1, values are updated to 1000x500, bug appears. If I set values manually by calling setSize() on N8AOPostPass instance to setSize(2x1000, 2x500) it starts working correctly again

versions

"@react-three/drei": "^9.97.5",
"@react-three/fiber": "^8.15.16",
"@react-three/postprocessing": "^2.16.2",
"postprocessing": "^6.35.3",
"three": "^0.161.0",

Can anyone help with this? I can help with fix if you can explain a bit more of how it works. Thanks in advance

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the N8AOPostPass behavior described in the issue and reproduce the case by changing renderer DPR from 2 to 1 in the listed react-postprocessing and three setup. Trace how its size values update; done means adaptiveDpr changes no longer produce spurious reflections after the DPR transition.

Written by the indexing model from the issue text.

Assessment

Tech stack
react, three.js, typescript
Domain
frontend, performance, web-dev
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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