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The Reducer — Blender add-on

Lower a mesh's polygon count and shrink its texture maps while keeping the UV texture mapping intact — everything keeps landing on the exact same places, just at lower resolution.

It's a separate extension from Painted 3MF Export (its own zip / entry in Preferences); the two don't depend on each other.


Why the mapping is preserved

UV coordinates are normalized 0..1 values stored per face-corner, independent of both image resolution and polygon density:

  • Texture size — a 4096² and a 1024² image are sampled by the exact same UVs. Shrinking the image changes detail, never where it lands. UVs are untouched.
  • Polygon count — the Decimate Collapse modifier interpolates and carries the UVs along with the surviving vertices, so the texture keeps mapping to the same surfaces.

Install

  1. Blender 4.2+ / 5.x: Edit ▸ Preferences ▸ Get Extensions ▸ ▾ ▸ Install from Disk… and pick the_reducer-1.2.0.zip (or drag the zip into the Blender window).
  2. Enable it if it isn't already.

No external dependencies.

Use

  1. Select your mesh (make it the active object).
  2. Open the N-panel in the 3D Viewport → "Reducer" tab.
  3. Set the Polygon Reduction % and the Max Texture Size.
  4. Click Reduce.

By default it produces an independent copy <name>_reduced and leaves your original untouched.

Settings

Setting Meaning
Merge Vertices (by Distance) (Pre-Clean) Weld duplicate / near-coincident vertices before reducing, at the given Merge Distance. Cleans up split-vertex exports (CAD, photogrammetry, some GLB/FBX) so Decimate collapses evenly. UVs are untouched
Instant Clean (Pre-Clean; shown only when the Instant Clean add-on is installed) Run Instant Clean's Clean command on the object before reducing, using the settings from Instant Clean's own panel
Reduce Polygons Toggle mesh decimation on/off
Method (shown only when Exoside's Quad Remesher add-on is installed) Decimate — collapse edges, fast, triangles out; or Quad Remesher — rebuild clean quad topology with the external engine, then transfer the original UVs onto it
Polygon Reduction Percent of triangles to remove (60% keeps 40%). Live readout shows current → projected face count (for Quad Remesher, the projected target quad count)
Transfer UVs (Quad Remesher method only) Quad Remesher output has no UVs; copy the original mesh's UV layout onto the new topology (Data Transfer, nearest-face interpolated) so textures keep mapping to the same surfaces
Preserve Symmetry Collapse symmetrically across X/Y/Z so a mirrored model stays mirrored
Triangulate Result Keep the collapsed geometry triangulated (recommended for 3D-print / 3MF)
Keep Decimate Live Leave the Decimate as an unapplied modifier so you can fine-tune the ratio in the Modifier panel instead of baking it now
Reduce Textures Toggle texture down-scaling on/off
Max Texture Size Cap the longest edge (4096 / 2048 / 1024 / 512 / 256). Smaller images are never upscaled; non-square images keep their aspect
Maps Resize All Maps (base color, roughness, normal, …) or Base Color Only
Apply To New Copy (<name>_reduced, original untouched) or Active Object (rewires its materials to the reduced textures)

Quad Remesher method

When Exoside's Quad Remesher add-on is installed and enabled, a Method selector appears in the Polygons section. Picking Quad Remesher:

  • Computes the target quad count from your Polygon Reduction % (a quad ≈ 2 triangles) and hands it to the engine. Symmetry maps to the engine's X/Y/Z symmetry. Every other engine setting (adaptive size, hard edges, …) is taken from the Quad Remesher panel as you configured it there.
  • The engine runs in the background — the Reduce button returns immediately and a status line under it shows progress. When the retopo lands, The Reducer finishes the job: transfers the original UVs onto the new topology (Quad Remesher output has none), triangulates if requested, applies New Copy / Active Object semantics, and reduces textures.
  • One remesh runs at a time, and a licensed/activated Quad Remesher engine is required (run it once from its own panel first if you never have).
  • Because the run is asynchronous, it isn't a single undo step — use New Copy (the default) to keep the original safe.

Pre-Clean

The Pre-Clean section at the top of the panel runs before any reduction, in the order shown:

  1. Merge Vertices (by Distance) — a remove_doubles weld. Runs on the target object (the copy in New Copy mode), so the original is never touched.
  2. Instant Clean — invoked only if that add-on is installed and the box is checked; it cleans per your Instant Clean settings.

The reduction percentage applies to the cleaned triangle count. With the Quad Remesher method, the engine remeshes the original object, so pre-clean runs only in Active Object mode there (in New Copy mode it is skipped and the report says so).

Notes

  • Each reduced texture is a new packed image (<name>_reduced) embedded in the .blend, so the change persists on save/reload. Your original images — and any external files they came from — are never modified.
  • Very aggressive polygon reduction can smear the texture near UV-island seams; moderate reductions (40–60%) stay clean.
  • Decimate Collapse keeps a watertight mesh watertight — good for the 3MF pipeline, but eyeball the result before printing after heavy reduction.

License

GPL-3.0-or-later.

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Blender add-on that reduces polygon count and texture size while preserving UV mapping — with optional pre-clean (merge by distance, Instant Clean)

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