From 819c9688e787a5fc70c1acfca8a86d752f05c8cf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=27=C3=A9lectron=20rare?=
 <108685187+electron-rare@users.noreply.github.com>
Date: Mon, 18 May 2026 21:43:27 +0200
Subject: [PATCH] feat(avlivebody-mac): 91-joint skeleton entity

Yellow marker spheres pooled per pid; ARKit (x,y,z) ->
RealityKit (x,-y,-z). Adapted .systemYellow to NSColor for
macOS RealityKit Material.Color. Build deferred to T8.
---
 .../Sources/AVLiveBody/SkeletonEntity.swift   | 57 +++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 avlivebody-mac/Sources/AVLiveBody/SkeletonEntity.swift

diff --git a/avlivebody-mac/Sources/AVLiveBody/SkeletonEntity.swift b/avlivebody-mac/Sources/AVLiveBody/SkeletonEntity.swift
new file mode 100644
index 0000000..4392dc8
--- /dev/null
+++ b/avlivebody-mac/Sources/AVLiveBody/SkeletonEntity.swift
@@ -0,0 +1,57 @@
+import AVLiveWire
+import AppKit
+import Foundation
+import RealityKit
+import simd
+
+/// Renders 91-joint skeletons as yellow marker spheres. One marker
+/// pool per pid. ARKit world coords -> RealityKit space (x, -y, -z).
+@MainActor
+final class SkeletonEntity {
+    let root = Entity()
+
+    private static let jointCount = 91
+    private static let markerRadius: Float = 0.012
+
+    private var pools: [Int: [ModelEntity]] = [:]
+    private let mesh = MeshResource.generateSphere(radius: markerRadius)
+    private let material = SimpleMaterial(
+        color: NSColor.systemYellow, roughness: 0.6, isMetallic: false)
+
+    func update(_ skeletons: [Int: SkeletonPayload]) {
+        // Drop pools for pids no longer present.
+        for pid in pools.keys where skeletons[pid] == nil {
+            pools[pid]?.forEach { $0.removeFromParent() }
+            pools.removeValue(forKey: pid)
+        }
+        for (pid, payload) in skeletons {
+            let pool = pools[pid] ?? makePool()
+            pools[pid] = pool
+            let n = min(Self.jointCount, payload.joints.count,
+                        payload.valid.count)
+            for i in 0..<n {
+                let marker = pool[i]
+                if payload.valid[i] {
+                    let j = payload.joints[i]
+                    marker.transform.translation =
+                        SIMD3<Float>(j.x, -j.y, -j.z)
+                    marker.isEnabled = true
+                } else {
+                    marker.isEnabled = false
+                }
+            }
+        }
+    }
+
+    private func makePool() -> [ModelEntity] {
+        var pool: [ModelEntity] = []
+        pool.reserveCapacity(Self.jointCount)
+        for _ in 0..<Self.jointCount {
+            let e = ModelEntity(mesh: mesh, materials: [material])
+            e.isEnabled = false
+            root.addChild(e)
+            pool.append(e)
+        }
+        return pool
+    }
+}