UV Islands Edge — Addon for Blender 5.x

UV Islands Edge is an addon for Blender 5.x that analyzes UV islands in Edit Mode, calculates their contours and spatial relationships, and draws that information in the UV editor to detect and fix issues such as overlaps, UDIM placement errors, flipped faces, and islands that are too close.

From the file: "UV Islands Edge — Addon for Blender 5.x packaged as Extension (blender_manifest.toml)."
From the file: "Author: Edwin Ca Be"

Core Functionality

• Island detection: groups faces into UV islands based on coordinates and connectivity.
• Boundary extraction: finds contours and generates offset lines for visualization.
• Overlap detection: checks overlaps using segment intersection and point-in-polygon.
• Proximity measurement: calculates minimum distances between island edges.
• Face orientation analysis: detects flipped and rotated faces, classifies as horizontal or vertical.
• UDIM grouping: assigns islands to UDIM tiles, detects crossings and out-of-range positions.

Visualization in the UV Editor

• Draws contours with configurable colors (normal, near, overlapping).
• Optional heatmap render showing proximity.
• Orientation arrows with short labels (H, V, R, M).
• UDIM view: colors by tile, draws grid, and shows tile numbers.

Automatic Features and Utilities

• Auto-detect handler with debounce to avoid constant recomputation.
• Smart Pack per UDIM: temporarily moves islands to [0,1) for packing, then restores.
• Fix Mirrored Faces: corrects flipped faces.
• Select by flag: selects faces with issues (mirrored, rotated, overlapping).
• UDIM report export: generates report of islands, overlaps, and out-of-range positions.

Typical Workflow and Tips

1. Activate the addon and recalculate contours in the UV/Image Editor.
2. Enable Auto-detect for live updates.
3. Inspect colors and arrows to locate issues.
4. Use Fix Mirrored or Select by Flag to correct.
5. Run Smart Pack to pack by UDIM.

Tip: In scenes with many islands, overlap calculation can be skipped for performance. Use only selected or adjust thresholds.

Why This Helps

• Saves time by visually showing UV issues.
• Reduces export/texturing errors by detecting overlaps and flipped faces early.
• Automates repetitive tasks like per-tile packing, useful in multi-UDIM pipelines.