BrickVision

LegoBrain (brain.py) reads .config section [brain]: backend = mock, gemini, deepseek, openrouter, or nova; model overrides per provider (defaults include gemini-2.5-flash, DeepSeek chat, OpenRouter model IDs). Mock mode returns canned grids (tower, house, hollow_cube, horse, …). Live backends call the configured API with a “Master LEGO Architect” style system prompt; responses are stripped of markdown fences before grid extraction. API keys load from .env (GEMINI_API_KEY, DEEPSEEK_API_KEY, OPENROUTER_API_KEY).

Grid semantics and engine parse_grid splits on double newlines into 2D character layers. COLOR_MAP maps letters (e.g. X/Y yellow, R red, B blue, K black, W white) to LDraw color IDs. BRICK_PARTS fixes the catalog to Duplo-like stacking: 2×4 (3001), 2×2 (3003), 1×2 (3004), 1×1 (3005). A greedy layer optimizer places bricks; save_ldr emits absolute-positioned 1 lines with stud spacing (20 LDU) and 24 LDU layer height. Optional force_symmetry mirrors rows for symmetric builds. prefer_larger_bricks trades strict per-cell color for fewer, larger parts when enabled in CLI prompts.

3D mesh path voxelizer.py uses trimesh to load meshes, voxelize at a configurable pitch (default 1 stud), optionally binary_fill_holes via SciPy, and map occupied cells into letter grids. If part count exceeds ~10k, app.py increases pitch and re-voxelizes. [voxel] flip_forward_stems in .config lists model filename stems whose forward axis is flipped so GLB/glTF exports face the intended direction in LDraw viewers.

Artifacts and resources Prompt runs write the cleaned grid to generated_input/<prompt>.txt and the raw model transcript to raw_input/<prompt>.raw.txt for debugging. ldraw_build.py resolves data/parts.csv or resoruces/parts.csv and local LDraw libraries for validation; viewers need an external parts/ tree pointed at in LeoCAD or similar.

Entry: python app.py with no args enters interactive prompt mode (optional CLI question for prefer_larger_bricks). Passing a mesh path runs the voxel pipeline; passing a text prompt string runs LegoBrain → outputs/<stem>.ldr.

Key modules: lego_engine.py — parse_grid, voxel_array_to_layers, count_parts, save_ldr; brain.py — LegoBrain.generate_grid_with_raw; voxelizer.py — load_and_voxelize with flip_forward; ldraw_build.py — standalone build helper with multi-path CSV discovery.

Tests: tests/ includes Gemini prompt regression tests, OpenRouter/DeepSeek wiring checks, and grid robustness (e.g. ragged rows guarded in placement).