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newblender

Discovery 01 — Blender source module map (source lens, first pass)

  • Date: 2026-10-07 · Feeds: RFC 0001 R2 (source lens)
  • Source tree: ~/agent-native-lab-data/sources/blender/projects.blender.org/blender/blender (5.x)
  • Method: directory survey + line counts (C/C++/GLSL/Py), key call paths read in source. First pass by an exploration agent; line numbers are approximate pointers, re-verify before relying on them.

1. Layers by size (~3.25M lines total)

Section titled “1. Layers by size (~3.25M lines total)”
Group ~Lines Share Main directories
Data model 1.01M ~31% makesdna (51k), makesrna (199k), blenkernel (376k), blenlib (194k), bmesh (83k), blenloader (57k), imbuf (40k)
Evaluation / computation 0.40M ~12% depsgraph (25k), nodes (157k), functions (13k), geometry (44k), modifiers (59k), animrig (21k), intern solvers (~70k)
Rendering 0.72M ~22% draw (208k), gpu (149k), intern/cycles (224k), freestyle (85k), compositor (35k), render (16k)
Human interface 0.93M ~29% editors (805k: sculpt_paint 107k, interface 90k, transform 50k, mesh 46k, object 43k, space_view3d 42k, animation 37k), windowmanager (62k), intern/ghost (59k), blenfont (8k), plus scripts/startup/bl_ui (2.2 MB of Python UI layout)
I/O + Python 0.15M ~5% io (61k: usd, alembic, fbx, obj, ply, stl…), python (91k: bpy, mathutils, bmesh, gpu)

Nuance: editors/ mixes real logic (sculpt brushes, mesh/object operators) with UI. The pure UI toolkit + windowing (interface, windowmanager, ghost, space_*) is closer to 12–15%. The rest of editors/ is logic trapped behind operators, which is the interesting part to free, not delete.

2. A click’s path to data

Section titled “2. A click’s path to data”
Hop What happens Key location
1. Operator Registered via WM_operatortype_append(); poll → invoke → exec windowmanager/intern/wm_operator_type.cc, wm_event_system.cc; ops in editors/*/…_ops.cc; Python path python/intern/bpy_operator_function.cc → WM_operator_call_py()
2. RNA write RNA_property_*_set() then RNA_property_update() → per-property update callback + depsgraph tag. Context-free variant exists: RNA_property_update_main(Main*, Scene*, …) makesrna/intern/rna_access.cc; bpy setattr in python/intern/bpy_rna.cc
3. DNA Setter writes a plain C struct field makesdna/DNA_*_types.h, mapped in makesrna/intern/rna_<type>.cc
4. Depsgraph Tag DEG_id_tag_update(); evaluation is driven by the window-manager event loop (wm_event_do_depsgraph → BKE_scene_graph_update_tagged → DEG_evaluate_on_refresh). Headless: BKE_scene_graph_evaluated_ensure() depsgraph/intern/depsgraph_tag.cc, depsgraph_eval.cc, blenkernel/intern/scene.cc

3. The GUI coupling (bContext)

Section titled “3. The GUI coupling (bContext)”
  • struct bContext (blenkernel/intern/context.cc) carries window/area/region slots; CTX_wm_area/region/space_* return null without a GUI.
  • ~1,909 ot->poll = assignments in editors/; most common is ED_operator_editmesh (120 uses). Shared polls in editors/screen/screen_ops.cc.
  • ~1,993 CTX_wm_(area|region|space_*) call sites under editors/.
  • Poll failure → “context is incorrect” (python/intern/bpy_operator_function.cc). Workaround today: Context.temp_override() (python/intern/bpy_rna_context.cc), i.e. faking a GUI for an agent.

4. Existing headless entry points

Section titled “4. Existing headless entry points”
Mechanism What Where
WITH_PYTHON_MODULE Build bpy as an importable Python module CMakeLists.txt (~226); source/creator/creator.cc; PyInit_bpy in python/intern/bpy_interface.cc
WITH_HEADLESS Build with no windowing (X11/Wayland/SDL off); selects GHOST_SystemHeadless CMakeLists.txt (~375); windowmanager/CMakeLists.txt; intern/ghost/CMakeLists.txt
-b / -c Runtime background mode, G.background = true source/creator/creator_args.cc

5. First observations for newblender (not decisions)

Section titled “5. First observations for newblender (not decisions)”
  1. The data model (DNA/RNA) and evaluation (depsgraph, nodes, functions) are already separable from the UI. RNA even has a context-free update path. The agent-facing core likely sits on RNA + depsgraph + nodes, not on operators.
  2. Operators are where human assumptions concentrate: poll-by-context, modal interaction, “select then act”. ~2k context call sites measure the size of that coupling.
  3. Evaluation is triggered by the event loop, a human-tempo heartbeat. An agent wants explicit “apply these changes → evaluate → give me the diff” transactions.
  4. Blender already ships headless builds, so “no GUI” is not the novelty. The novelty is an interface designed for agents rather than a GUI with the window removed.