depsgraph-and-evaluated-datalisted

# Depsgraph and Evaluated Data ## Trigger Use this skill when the user: - Is writing an exporter, measurement script, or inspection tool - Reports that "modifiers are missing from my export" or "the vertex positions don't match what I see" - Mentions `evaluated_depsgraph_get`, `evaluated_get`, `to_mesh`, `to_mesh_clear` - Reads from `obj.data.vertices` and gets unexpectedly raw geometry - Needs final positions after armature deformation, shape keys, modifiers, or geometry nodes ## The core misunderstanding `bpy.data.objects['Cube'].data.vertices` does not return what the user sees in the viewport. It returns the **mesh datablock as authored**, before any modifier, armature, shape key, or geometry nodes evaluation. The viewport shows **evaluated** geometry: the result of running the full dependency graph. Anything that downstream code consumes (renderers, exporters, measurement tools) almost always wants the evaluated form, not the raw form. ``` authored mesh (obj.data) | v modifier stack shape keys armature deform geometry nodes | v evaluated mesh (what you see) ``` ## The canonical pattern ```python import bpy def get_evaluated_mesh(obj): """Return a temporary mesh datablock with all modifiers applied. The caller must call obj_eval.to_mesh_clear() when done to free the temporary mesh. Do not store this mesh; treat it as read-only and short-lived. """ depsgraph = bpy.context.evaluated_depsgraph_get()