blender-geometry-nodes

1# Geometry Nodes
2 
3The execution model is in `blender-core`. Build trees with `scripts/gn_builder.py`, a compact JSON spec that's far cheaper than raw bpy. Look up exact socket names first, because they change between versions:
4```
5scripts/gn_builder.py -- --describe GeometryNodeDistributePointsOnFaces GeometryNodeInstanceOnPoints
6scripts/gn_builder.py -- --spec scatter.json --apply Ground --set Density=20 Seed=3 Mask=@paint_mask
7```
8`--set Name=@attr` feeds a modifier input from a named attribute. The result reports evaluated vert/face counts and node warnings. The spec format is in the script docstring; full examples are in [references/recipes.md](references/recipes.md).
9 
10## Core concepts (get these right or nothing works)
11- **Geometry** flows left→right through sockets with **circle** shapes. **Fields** (diamond sockets) are functions evaluated per element **on the node that consumes them**, in that node's domain/context.
12- **Domains**: Point, Edge, Face, Face Corner, Spline, Instance, Layer. `Capture Attribute` freezes a field at a point in the graph (before topology changes), and `Evaluate on Domain` converts between domains.
13- **Attributes**: built-ins (`position`, `normal`, `sharp_face`, `material_index`, `UVMap`...) plus named ones via `Store Named Attribute`. Named attributes persist after the modifier. That's how GN data reaches shaders (Attribute node) and exporters (glTF `export_attributes`, which exports names starting with `_`).
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