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Cavity dirt material with vertical streaks

Build a grime node material where dirt collects in crevices found by ambient occlusion and runs down in vertical streaks from a noise stretched along Z, darkening and roughening a base colour. Use it for buildings, statues, machinery and props that need dirt in the right places.

Recorded render of Cavity dirt material with vertical streaks

What this component contains

  • ATTRIBUTION.md
  • LICENSE
  • README.md
  • component.json
  • graphcheck.py
  • material_cavity_dirt.py
  • meshcheck.py
  • preview.png
  • test_material_cavity_dirt.py
  • test_package.py
  • verification/native.json

How it works

Operator
baltor.material_cavity_dirt
Parameters
material_name, base_color, dirt_color, ao_distance, dirt_amount, streaks, streak_scale, assign
Result
One material with a node tree; assigned to the active object.
Blender
4.2 or later
Axes
Blender Z up, -Y forward
Units
metres

Recorded checks

blender 5.2.1 LTS (hash 9e2066aef7ef built 2026-08-25 02:12:34)

  • addon_install_and_enable
  • operator_runs_with_defaults
  • blender_data_matches_core
  • addon_disable_unregisters
  • script_mode_runs
  • clean_reopen_addon_file
  • clean_reopen_script_file
  • gltf_separate_export
  • engine_output_clean

Limits to consider

Cavities come from the Ambient Occlusion shader node: ray traced in Cycles, screen-space approximated in EEVEE, so results differ. Streaks follow object Z and do not know about ledges or drip sources. Dirt is colour and roughness only, without bump. Rendered here with Cycles CPU only. Verified in Blender 5.2.1; written for the 4.2 API.