Mimir/docs/scene-editor-control-surface.md

Mimir Scene Editor Control Surface

Mimir now has a runtime-owned scene editor state for arranging the visible presentation inputs inside the Fensalir-hosted Mimir window. This editor is not the OBS program output. It is an operator surface for placing source panels, text panels, and imported-model placeholders before later renderer cuts turn those nodes into final composited pixels or volumetric field claims.

Authority Map

• Owner: MimirSceneEditorState owns editor camera, scene nodes, selected node, visibility, lock state, 2D-plane transform, and active gizmo mode.
• Inputs: rolling video buffers provide sensor-feed nodes; Fensalir InputState provides mouse/key edits; the Mimir UI provides visibility, reset, transform, text, and model-path commands.
• Outputs: MimirRuntime reads the editor state into the Fensalir frame camera, spline outlines, selection gizmos, and SDF handle markers.
• Derived state: the hierarchy text, selected-node readout, editor splines, and handle SDF objects are derived from the editor graph. They do not own node truth.
• Forbidden writers: program-composite controls, OBS source endpoints, bridge scripts, and FieldEvidence surface intents do not decide editor transforms.
• Shared paths: UI buttons/sliders and mouse-drag gizmos all commit through MimirSceneEditorState; reset returns to each node's stored default transform.
• Deletion line: do not add a separate transform cache in the renderer or OBS path. Fensalir may later render richer node types, but it should consume this graph or a deliberate successor, not invent a competing editor graph.

Current Controls

• Mimir Editor panel exposes the scene graph, selected-node visibility and lock toggles, transform reset, camera reset, and transform sliders.
• Active gizmo modes are Grab, Rotate, and Resize; keys 1, 2, and 3 switch modes, and left-drag applies the active mode to the selected node.
• Sensor-feed nodes are created from live video rolling buffers.
• SDF text panels and model placeholders can be added from the panel.
• --scene-editor-smoke proves graph creation, visibility toggles, transform reset, mouse-drag transform edits, text-node creation, model placeholder import, and derived gizmo geometry.

Renderer Hooks Still Open

• World SDF text: Fensalir currently has DirectWrite overlay text and SDF object proxies. Scene text needs a renderer-owned SDF/MSDF glyph atlas plus billboard or mesh text lowering before text glyphs are truly drawn inside the scene.
• Imported models: Fensalir resource contracts already know mesh packages, but selected mesh draw/material lowerings are still future work. The current import control creates graph nodes with paths; it does not decode ASSIMP meshes or upload vertex/index resources yet.
• Pixel-accurate gizmo hit-testing: current gizmo edits apply to the selected node. Fensalir needs an editor hit-test path before handles can be clicked directly in world space.