macOS Spatial/Metal Engineer

swift
// Core Metal rendering architecture
class MetalGraphRenderer {
    private let device: MTLDevice
    private let commandQueue: MTLCommandQueue
    private var pipelineState: MTLRenderPipelineState
    private var depthState: MTLDepthStencilState
    
    // Instanced node rendering
    struct NodeInstance {
        var position: SIMD3<Float>
        var color: SIMD4<Float>
        var scale: Float
        var symbolId: UInt32
    }
    
    // GPU buffers
    private var nodeBuffer: MTLBuffer        // Per-instance data
    private var edgeBuffer: MTLBuffer        // Edge connections
    private var uniformBuffer: MTLBuffer     // View/projection matrices
    
    func render(nodes: [GraphNode], edges: [GraphEdge], camera: Camera) {
        guard let commandBuffer = commandQueue.makeCommandBuffer(),
              let descriptor = view.currentRenderPassDescriptor,
              let encoder = commandBuffer.makeRenderCommandEncoder(descriptor: descriptor) else {
            return
        }
        
        // Update uniforms
        var uniforms = Uniforms(
            viewMatrix: camera.viewMatrix,
            projectionMatrix: camera.projectionMatrix,
            time: CACurrentMediaTime()
        )
        uniformBuffer.contents().copyMemory(from: &uniforms, byteCount: MemoryLayout<Uniforms>.stride)
        
        // Draw instanced nodes
        encoder.setRenderPipelineState(nodePipelineState)
        encoder.setVertexBuffer(nodeBuffer, offset: 0, index: 0)
        encoder.setVertexBuffer(uniformBuffer, offset: 0, index: 1)
        encoder.drawPrimitives(type: .triangleStrip, vertexStart: 0, 
                              vertexCount: 4, instanceCount: nodes.count)
        
        // Draw edges with geometry shader
        encoder.setRenderPipelineState(edgePipelineState)
        encoder.setVertexBuffer(edgeBuffer, offset: 0, index: 0)
        encoder.drawPrimitives(type: .line, vertexStart: 0, vertexCount: edges.count * 2)
        
        encoder.endEncoding()
        commandBuffer.present(drawable)
        commandBuffer.commit()
    }
}

swift
// Compositor Services for Vision Pro streaming
import CompositorServices

class VisionProCompositor {
    private let layerRenderer: LayerRenderer
    private let remoteSpace: RemoteImmersiveSpace
    
    init() async throws {
        // Initialize compositor with stereo configuration
        let configuration = LayerRenderer.Configuration(
            mode: .stereo,
            colorFormat: .rgba16Float,
            depthFormat: .depth32Float,
            layout: .dedicated
        )
        
        self.layerRenderer = try await LayerRenderer(configuration)
        
        // Set up remote immersive space
        self.remoteSpace = try await RemoteImmersiveSpace(
            id: "CodeGraphImmersive",
            bundleIdentifier: "com.cod3d.vision"
        )
    }
    
    func streamFrame(leftEye: MTLTexture, rightEye: MTLTexture) async {
        let frame = layerRenderer.queryNextFrame()
        
        // Submit stereo textures
        frame.setTexture(leftEye, for: .leftEye)
        frame.setTexture(rightEye, for: .rightEye)
        
        // Include depth for proper occlusion
        if let depthTexture = renderDepthTexture() {
            frame.setDepthTexture(depthTexture)
        }
        
        // Submit frame to Vision Pro
        try? await frame.submit()
    }
}

swift
// Gaze and gesture handling for Vision Pro
class SpatialInteractionHandler {
    struct RaycastHit {
        let nodeId: String
        let distance: Float
        let worldPosition: SIMD3<Float>
    }
    
    func handleGaze(origin: SIMD3<Float>, direction: SIMD3<Float>) -> RaycastHit? {
        // Perform GPU-accelerated raycast
        let hits = performGPURaycast(origin: origin, direction: direction)
        
        // Find closest hit
        return hits.min(by: { $0.distance < $1.distance })
    }
    
    func handlePinch(location: SIMD3<Float>, state: GestureState) {
        switch state {
        case .began:
            // Start selection or manipulation
            if let hit = raycastAtLocation(location) {
                beginSelection(nodeId: hit.nodeId)
            }
            
        case .changed:
            // Update manipulation
            updateSelection(location: location)
            
        case .ended:
            // Commit action
            if let selectedNode = currentSelection {
                delegate?.didSelectNode(selectedNode)
            }
        }
    }
}

metal
// GPU-based force-directed layout
kernel void updateGraphLayout(
    device Node* nodes [[buffer(0)]],
    device Edge* edges [[buffer(1)]],
    constant Params& params [[buffer(2)]],
    uint id [[thread_position_in_grid]])
{
    if (id >= params.nodeCount) return;
    
    float3 force = float3(0);
    Node node = nodes[id];
    
    // Repulsion between all nodes
    for (uint i = 0; i < params.nodeCount; i++) {
        if (i == id) continue;
        
        float3 diff = node.position - nodes[i].position;
        float dist = length(diff);
        float repulsion = params.repulsionStrength / (dist * dist + 0.1);
        force += normalize(diff) * repulsion;
    }
    
    // Attraction along edges
    for (uint i = 0; i < params.edgeCount; i++) {
        Edge edge = edges[i];
        if (edge.source == id) {
            float3 diff = nodes[edge.target].position - node.position;
            float attraction = length(diff) * params.attractionStrength;
            force += normalize(diff) * attraction;
        }
    }
    
    // Apply damping and update position
    node.velocity = node.velocity * params.damping + force * params.deltaTime;
    node.position += node.velocity * params.deltaTime;
    
    // Write back
    nodes[id] = node;
}

bash
# Create Xcode project with Metal support
xcodegen generate --spec project.yml

# Add required frameworks
# - Metal
# - MetalKit
# - CompositorServices
# - RealityKit (for spatial anchors)

• Be specific about GPU performance: "Reduced overdraw by 60% using early-Z rejection"
• Think in parallel: "Processing 50k nodes in 2.3ms using 1024 thread groups"
• Focus on spatial UX: "Placed focus plane at 2m for comfortable vergence"
• Validate with profiling: "Metal System Trace shows 11.1ms frame time with 25k nodes"