Initial commit for first version of project

GasTankAR/Views/TankAR/ReferenceImageProvider.swift

@@ -0,0 +1,56 @@
+//
+//  ReferenceImageProvider.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import ARKit
+import UIKit
+
+/// Liefert die Referenzbilder für die Anker-Erkennung. Bevorzugt die AR-Ressourcengruppe
+/// „ARMarkers"; fällt sonst auf einen programmatisch erzeugten Platzhalter-Marker zurück.
+enum ReferenceImageProvider {
+    static func load() -> Set<ARReferenceImage> {
+        if let group = ARReferenceImage.referenceImages(inGroupNamed: "ARMarkers", bundle: .main) {
+            return group
+        }
+        if let placeholder = makePlaceholder() {
+            return [placeholder]
+        }
+        return []
+    }
+
+    private static func makePlaceholder() -> ARReferenceImage? {
+        let size = CGSize(width: 512, height: 512)
+        let renderer = UIGraphicsImageRenderer(size: size)
+        let image = renderer.image { context in
+            let cg = context.cgContext
+            UIColor.white.setFill()
+            cg.fill(CGRect(origin: .zero, size: size))
+
+            let palette: [UIColor] = [.black, .systemBlue, .systemRed, .systemGreen, .systemOrange, .systemPurple]
+            let cells = 8
+            let cellSize = size.width / CGFloat(cells)
+            for row in 0..<cells {
+                for column in 0..<cells {
+                    let index = (row * cells + column) % palette.count
+                    palette[index].setFill()
+                    let rect = CGRect(
+                        x: CGFloat(column) * cellSize,
+                        y: CGFloat(row) * cellSize,
+                        width: cellSize,
+                        height: cellSize
+                    )
+                    if (row + column).isMultiple(of: 2) {
+                        cg.fillEllipse(in: rect.insetBy(dx: 4, dy: 4))
+                    } else {
+                        cg.fill(rect.insetBy(dx: 6, dy: 6))
+                    }
+                }
+            }
+        }
+        guard let cgImage = image.cgImage else { return nil }
+        return ARReferenceImage(cgImage, orientation: .up, physicalWidth: 0.15)
+    }
+}