The Skung Rockification of Ziggy Skungdust and the SIMD's

Sources/JolkEngine/Loaders/VMeshLoader.swift

@@ -0,0 +1,118 @@
+import Foundation
+import Maths
+
+
+struct VMeshLoader: LoaderProtocol
+{
+	typealias T = Mesh<VMeshVertex>
+
+	func load(url: URL) -> T? { try? Self.read(url: url) }
+	func load(url: URL, content: inout ContentManager) -> T? { load(url: url) }
+
+	static func read(url: URL) throws -> T
+	{
+		let file = try FileHandle(forReadingFrom: url)
+
+		// read header fields
+		let header = VMeshHeader(
+			magic:        try file.read(upToCount: 4),
+			version:      try file.read(as: UInt8.self).littleEndian,
+			idxSize:      try file.read(as: UInt8.self).littleEndian,
+			subMeshCount: try file.read(as: UInt16.self).littleEndian,
+			vertexCount:  try file.read(as: UInt32.self).littleEndian,
+			indexCount:   try file.read(as: UInt32.self).littleEndian)
+
+		// header sanity checks
+		guard header.magic == Data("VMSH".utf8)
+		else { throw NSError() }
+		guard header.version == 2
+		else { throw NSError() }
+
+		// check index type
+		let idxSize = switch header.idxSize
+		{
+		case 1, 2, 4: header.idxSize
+		default: throw NSError()
+		}
+
+		// fail on empty data lengths
+		guard header.vertexCount > 0, header.indexCount > 0
+		else { throw NSError() }
+
+		// read submeshes
+		var subMeshes = [VMeshSubMesh](repeating: .empty, count: Int(header.subMeshCount))
+		for i in 0..<Int(header.subMeshCount)
+		{
+			guard let nameStr = try file.read(upToCount: 24)
+			else { throw NSError() }
+			subMeshes[i] = .init(
+				name: String(decoding: nameStr, as: UTF8.self),
+				offset: try file.read(as: UInt32.self),
+				count: try file.read(as: UInt32.self))
+		}
+
+		// read vertices
+		var vertices = [VMeshVertex](repeating: .empty, count: Int(header.vertexCount))
+		for i in 0..<Int(header.vertexCount)
+		{
+			vertices[i] = .init(
+				position: .init(try file.read(as: Float.self), try file.read(as: Float.self), try file.read(as: Float.self)),
+				//texCoord: .init(try file.read(as: UInt16.self), try file.read(as: UInt16.self)),
+				texCoord: .init(
+					Float(try file.read(as: UInt16.self)) / Float(UInt16.max),
+					1.0 - Float(try file.read(as: UInt16.self)) / Float(UInt16.max)),
+				normal: .init(try file.read(as: Int8.self), try file.read(as: Int8.self), try file.read(as: Int8.self), try file.read(as: Int8.self)),
+				tangent: .init(try file.read(as: Int8.self), try file.read(as: Int8.self), try file.read(as: Int8.self), try file.read(as: Int8.self)))
+		}
+
+		let indices = switch idxSize
+		{
+		case 1: try (0..<Int(header.indexCount)).map { _ in UInt16(try file.read(as: UInt8.self)) }
+		case 2: try (0..<Int(header.indexCount)).map { _ in UInt16(try file.read(as: UInt16.self)) }
+		case 4: try (0..<Int(header.indexCount)).map { _ in UInt16(try file.read(as: UInt32.self)) }
+		default: fatalError()
+		}
+
+		// create & return mesh
+		return .init(
+			vertices: vertices, indices: indices,
+			subMeshes: .init(uniqueKeysWithValues:
+				subMeshes.map { ($0.name, .init(start: Int($0.offset), length: Int($0.count))) }
+			)
+		)
+	}
+
+	struct VMeshHeader
+	{
+		let magic: Data?
+		let version, idxSize: UInt8
+		let subMeshCount: UInt16
+		let vertexCount, indexCount: UInt32
+	}
+}
+
+
+public struct VMeshVertex: Vertex
+{
+	let position: Vec3f
+	//let texCoord: SIMD2<UInt16>
+	let texCoord: Vec2f
+	let normal: SIMD4<Int8>
+	let tangent: SIMD4<Int8>
+}
+
+extension VMeshVertex
+{
+	static let empty: Self = .init(position: .init(), texCoord: .init(), normal: .init(), tangent: .init())
+}
+
+struct VMeshSubMesh
+{
+	let name: String
+	let offset: UInt32, count: UInt32
+}
+
+extension VMeshSubMesh
+{
+	static let empty: Self = .init(name: .init(), offset: .init(), count: .init())
+}