Blender exporter, cluster demo app, and the 3D/animation fixes it needed

[corepunch]

What this adds

• tools/blender-export.py — runs inside Blender and writes an ORCA project's 3D assets: meshes (FBX → orca-fbx), shaders, materials, animation clips, a scene prefab, and a first-time package.lua and screen.
• apps/cluster-demo/ — a 1920×720 digital instrument cluster built procedurally in Blender and exported with the tool. Each gauge has a linear fill-up clip; the app drives a gauge by setting its AnimationPlayer.CurrentTime. Demo/FillAll.xml scrubs every gauge together as a stand-in for real inputs.
• orca-fbx (tools/fbx-import.cpp) — honours its arguments, creates the output directory, writes vertex colours, compiles against current headers and FBX SDK 2020.2. New make orca-fbx target.

Run the demo with build/bin/orca apps/cluster-demo after regenerating the meshes (see below).

Engine fixes

Getting an exported scene to render and animate in a running app exposed these:

SceneKit

• Viewport3D crashed when its parent was a Screen (no Node2D).
• Model3D discarded Material.BlendMode (unset node override came back as -1 through an unsigned parameter).
• Camera: removed the ×1.05 FOV factor and fixed the horizontal→vertical conversion (same fix as b45c771); Fov/ZNear/ZFar now have defaults.
• PrefabView3D loaded its prefab twice at startup.
• TextBlock3D has a Color property instead of always drawing white.

Core / renderer

• AnimationPlayer stalled after its first frame, and the frame clock did not advance on app-loop paints, so clips never played in a running app. The clock now advances in Screen's paint handler.
• Setting CurrentTime on a stopped player applies the clip (scrubbing).
• vec2/vec3/vec4 uniforms were corrupted by a missing break.
• A shader's BlendMode/DepthTestFunction/DepthWriteEnabled became uniforms and never reached the draw call.
• Render-pass tags were never registered.
• CDATA text in XML was dropped.
• Texture_Create crashed without a GL context.

Tools and docs

• tools/create-app.py generates package.lua (the runtime no longer reads package.xml).
• QUICKSTART.md, docs/animations.md and the orca-fbx premake project corrected.

Testing

• make test-headless and make test pass locally on macOS; a scrubbing test was added to tests/test_animations.lua.
• CI had been red on main since the SVG loader rework because three tests described removed code; they are brought up to date here: test_filesystem.c (tested the removed _ParseLoaderArgs), test_layout.lua (expected the removed &type=mask icon query, an ImageView in IconCard, and a centred panel to stretch), test_navigationhost.lua (looked for GameBack, now BackButton in the NavigationBar prefab).
• The demo was run in the engine on macOS and compared against the Blender render; animations were confirmed by capturing successive frames.

Skills

Two skills document the pipeline for agents: .opencode/skills/orca-blender-pipeline (authoring in Blender for the exporter) and .opencode/skills/orca-3d-scene (project layout, scene XML, shaders/uniforms, animation binding, running and verifying). .claude/skills and .agents/skills are symlinks to .opencode/skills so Claude Code and Codex find them; AGENTS.md lists them.

Reviewer notes

• Meshes are not in the PR. .gitignore ignores *.mesh, so apps/cluster-demo/Meshes/ only carries the <Mesh> declarations. Regenerate with Blender, the FBX SDK and make orca-fbx:
  blender -b apps/cluster-demo/blender/cluster.blend --python tools/blender-export.py -- apps/cluster-demo --collection InstrumentCluster
  (the headless invocation is untested; the export was run from an interactive Blender).
• Behaviour changes to check against existing content: camera FOV is ~5% narrower than before, Material.BlendMode now takes effect, and the frame clock advances on every screen paint.
• The exporter's texture path is untested (the demo has no images). Text in the demo is baked mesh, not TextBlock3D.
• Not addressed: no asset cache (each Model3D loads its own material and compiles its own shader), Viewport3D always draws to the full window, orthographic cameras are ignored, orca new still writes package.xml.

🤖 Generated with Claude Code