PostproductionRenderer: PEN style smears / leaves trails when SMAA and Outlines are enabled

[ynnob]

Describe the bug 📝

When using PostproductionRenderer with the PEN postproduction style, enabling both SMAA and Outlines causes visible smearing/ghosting artifacts. The frame is not fully re-rendered and previous strokes appear to accumulate over time (trail/smear effect).

Reproduction steps:

1. Enable postprocessing.
2. Set style to Pen.
3. Enable Outlines.
4. Enable SMAA.
5. Orbit/pan/zoom the camera.

Reproduction ▶️

No response

Steps to reproduce 🔢

No response

System Info 💻

System:
    OS: Windows 11 10.0.22631
    CPU: (8) x64 Intel(R) Core(TM) i7-9700 CPU @ 3.00GHz
    Memory: 28.84 GB / 63.92 GB
  Binaries:
    Node: 23.4.0 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.22 - C:\Program Files\nodejs\yarn.CMD
    npm: 11.4.2 - C:\Program Files\nodejs\npm.CMD
    pnpm: 10.12.4 - C:\Program Files\nodejs\pnpm.CMD
  Browsers:
    Chrome: 144.0.7559.133
    Edge: Chromium (143.0.3650.75)
    Firefox: 147.0.3 - C:\Program Files\Mozilla Firefox\firefox.exe
    Internet Explorer: 11.0.22621.3527

    "@thatopen/components": "^3.3.1",
    "@thatopen/components-front": "^3.3.1",
    "@thatopen/fragments": "^3.3.3",
    "@thatopen/ui": "^3.3.3",
    "@thatopen/ui-obc": "^3.3.3",

Used Package Manager 📦

npm

Error Trace/Logs 📃

No response

Validations ✅

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• Make sure this is a repository issue and not a framework-specific issue. For example, if it's a THREE.js related bug, it should likely be reported to mrdoob/threejs instead.
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• The provided reproduction is a minimal reproducible example of the bug.