refactor chunk rendering and fix chunk rendering precision loss at large positions

Sources/Voxelotl/Renderer/ChunkRenderer.swift

@@ -0,0 +1,42 @@
+import simd
+
+public struct ChunkRenderer {
+  private weak var _renderer: Renderer?
+  private var _renderChunks = [ChunkID: RendererMesh]()
+
+  public var material: Material
+
+  public init(renderer: Renderer) {
+    self._renderer = renderer
+    self.material = .init(ambient: .black, diffuse: .white, specular: .white, gloss: 20.0)
+  }
+
+  public mutating func draw(environment: Environment, camera globalCamera: Camera) {
+    let fChunkSz = Float(Chunk.size), divisor = 1 / fChunkSz
+    let origin = SIMD3<Int>(floor(globalCamera.position * divisor), rounding: .down)
+
+    let localCamera = Camera(globalCamera)
+    localCamera.position = globalCamera.position - SIMD3<Float>(origin) * fChunkSz
+
+    self._renderer!.setupBatch(environment: environment, camera: localCamera)
+    for (chunkID, mesh) in self._renderChunks {
+      let drawPos = SIMD3<Float>(SIMD3<Int>(chunkID) &- origin) * fChunkSz
+      self._renderer!.submit(
+        mesh: mesh,
+        instance: .init(world: .translate(drawPos)),
+        material: self.material)
+    }
+  }
+
+  public mutating func addChunk(id chunkID: ChunkID, mesh: RendererMesh) {
+    self._renderChunks.updateValue(mesh, forKey: chunkID)
+  }
+
+  public mutating func removeChunk(id chunkID: ChunkID) {
+    self._renderChunks.removeValue(forKey: chunkID)
+  }
+
+  public mutating func removeAll() {
+    self._renderChunks.removeAll()
+  }
+}