Fix generating walls instead bridges for multiple filaments printing #299

New Issue

MrUnknownDE · 2026-04-05T16:19:40+02:00

MrUnknownDE commented

2026-04-05 16:19:40 +02:00

Originally created by @Felixoid on 3/16/2026

Description

Fixes the long-standing issue where color-painting a bridge area causes the slicer to generate overhang perimeters instead of proper bridge infill. When a bridge surface is painted with a different filament color (via face painting, multi-body, or color painting tools), MMU segmentation splits it into a separate region. The per-region bridge detection then fails because the new region has no same-region geometry below — so instead of recognizing it as a bridge, the slicer prints unsupported perimeter walls in thin air.

This has been reported across multiple issues over several OrcaSlicer versions:

Fixes (not sure though, could be a different issue) OrcaSlicer/OrcaSlicer#11207
Fixes OrcaSlicer/OrcaSlicer#2845
Fixes OrcaSlicer/OrcaSlicer#4234
Fixes OrcaSlicer/OrcaSlicer#6328
Fixes OrcaSlicer/OrcaSlicer#7352

Screenshots/Recordings/Graphs

Current broken version:

Fixed version:

Tests

Added MMU tests.

MMU bridge preserved with bottom_shell_layers=0 and MMU face-painted bridge full pipeline check that the painted overhang surfaces are generated as bridges.

Example

Exampes of an affected project with upstream and fixed code is in Project.zip

*Originally created by @Felixoid on 3/16/2026* # Description Fixes the long-standing issue where color-painting a bridge area causes the slicer to generate overhang perimeters instead of proper bridge infill. When a bridge surface is painted with a different filament color (via face painting, multi-body, or color painting tools), MMU segmentation splits it into a separate region. The per-region bridge detection then fails because the new region has no same-region geometry below — so instead of recognizing it as a bridge, the slicer prints unsupported perimeter walls in thin air. This has been reported across multiple issues over several OrcaSlicer versions: - Fixes (not sure though, could be a different issue) OrcaSlicer/OrcaSlicer#11207 - Fixes OrcaSlicer/OrcaSlicer#2845 - Fixes OrcaSlicer/OrcaSlicer#4234 - Fixes OrcaSlicer/OrcaSlicer#6328 - Fixes OrcaSlicer/OrcaSlicer#7352 # Screenshots/Recordings/Graphs  Current broken version: <img width="2741" height="1954" alt="Screenshot_20260315_215306" src="https://github.com/user-attachments/assets/abf417f6-d861-4abe-8d35-128de5e2fb2a" /> <img width="2814" height="1901" alt="Screenshot_20260315_215400" src="https://github.com/user-attachments/assets/0b395067-b8a1-4c19-bed1-2eb0e82252c0" /> Fixed version: <img width="2741" height="1954" alt="Screenshot_20260315_215239" src="https://github.com/user-attachments/assets/d589bf32-0695-4218-b739-c4a8a9038b42" /> <img width="2814" height="1901" alt="Screenshot_20260315_215340" src="https://github.com/user-attachments/assets/f0ba32a5-1973-4cf9-93b8-ff30d40cbebc" /> ## Tests  Added MMU tests. `MMU bridge preserved with bottom_shell_layers=0` and `MMU face-painted bridge full pipeline` check that the painted overhang surfaces are generated as bridges. ## Example Exampes of an affected project with upstream and fixed code is in [Project.zip](https://github.com/user-attachments/files/26022978/Project.zip)

MrUnknownDE added the bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix bug-fix labels 2026-04-05 16:19:40 +02:00

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Reference: github/OrcaSlicer#299