Refactor runtime scene build and viewport host

src/runtime-three/runtime-scene-build.ts

@@ -1,6 +1,7 @@
 import type { Vec3 } from "../core/vector";
 import type { BoxBrush, BoxFaceId, FaceUvState } from "../document/brushes";
 import type { SceneDocument, WorldSettings } from "../document/scene-document";
+import { cloneWorldSettings } from "../document/world-settings";
 import { getPrimaryPlayerStartEntity } from "../entities/entity-instances";
 import { getBoxBrushBounds } from "../geometry/box-brush";
 import { cloneMaterialDef, type MaterialDef } from "../materials/starter-material-library";
@@ -213,18 +214,7 @@ export function buildRuntimeSceneFromDocument(document: SceneDocument, options:
         };
 
   return {
-    world: {
-      background: {
-        ...document.world.background
-      },
-      ambientLight: {
-        ...document.world.ambientLight
-      },
-      sunLight: {
-        ...document.world.sunLight,
-        direction: cloneVec3(document.world.sunLight.direction)
-      }
-    },
+    world: cloneWorldSettings(document.world),
     brushes,
     colliders,
     sceneBounds,

src/viewport-three/viewport-host.ts

@@ -3,7 +3,6 @@ import {
   AxesHelper,
   BoxGeometry,
   CanvasTexture,
-  Color,
   ConeGeometry,
   CylinderGeometry,
   DirectionalLight,
@@ -71,7 +70,7 @@ interface PlayerStartRenderObjects {
 export class ViewportHost {
   private readonly scene = new Scene();
   private readonly camera = new PerspectiveCamera(60, 1, 0.1, 1000);
-  private readonly renderer = new WebGLRenderer({ antialias: true });
+  private readonly renderer = new WebGLRenderer({ antialias: true, alpha: true });
   private readonly cameraTarget = new Vector3(0, 0, 0);
   private readonly cameraOffset = new Vector3();
   private readonly cameraForward = new Vector3();
@@ -137,6 +136,7 @@ export class ViewportHost {
     this.scene.add(this.boxCreatePreviewMesh);
     this.scene.add(this.boxCreatePreviewEdges);
     this.renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2));
+    this.renderer.setClearAlpha(0);
   }
 
   mount(container: HTMLElement) {
@@ -161,7 +161,7 @@ export class ViewportHost {
   }
 
   updateWorld(world: WorldSettings) {
-    this.scene.background = new Color(world.background.colorHex);
+    this.scene.background = null;
     this.ambientLight.color.set(world.ambientLight.colorHex);
     this.ambientLight.intensity = world.ambientLight.intensity;
     this.sunLight.color.set(world.sunLight.colorHex);