You need to compute the texture coordinates for each vertex, apply them to the mesh and supply a texture as a material to the mesh.
let geom = meshAnchor.geometry
let vertices = geom.vertices
let size = arFrame.camera.imageResolution
let camera = arFrame.camera
let modelMatrix = meshAnchor.transform
let textureCoordinates = vertices.map { vertex -> vector_float2 in
let vertex4 = vector_float4(vertex.x, vertex.y, vertex.z, 1)
let world_vertex4 = simd_mul(modelMatrix!, vertex4)
let world_vector3 = simd_float3(x: world_vertex4.x, y: world_vertex4.y, z: world_vertex4.z)
let pt = camera.projectPoint(world_vector3,
orientation: .portrait,
viewportSize: CGSize(
width: CGFloat(size.height),
height: CGFloat(size.width)))
let v = 1.0 - Float(pt.x) / Float(size.height)
let u = Float(pt.y) / Float(size.width)
return vector_float2(u, v)
}
// construct your vertices, normals and faces from the source geometry
// directly and supply the computed texture coords to create new geometry
// and then apply the texture.
let scnGeometry = SCNGeometry(sources: [verticesSource, textureCoordinates, normalsSource], elements: [facesSource])
let texture = UIImage(pixelBuffer: frame.capturedImage)
let imageMaterial = SCNMaterial()
imageMaterial.isDoubleSided = false
imageMaterial.diffuse.contents = texture
scnGeometry.materials = [imageMaterial]
let pcNode = SCNNode(geometry: scnGeometry)
pcNode if added to your scene will contain the mesh with the texture applied.
Texture coordinates computation from here
