From 4f835747b4d751999934e92a11c2421cdd55253a Mon Sep 17 00:00:00 2001
From: "Diego F. Goberna" <github@feiss.be>
Date: Sun, 25 May 2025 20:52:15 +0200
Subject: [PATCH 1/2] tweak multiple viewports example

---
 examples/assets.json                    |  4 ++
 examples/multiple-viewpoints/index.html | 82 +++++++++++++++++++------
 2 files changed, 66 insertions(+), 20 deletions(-)

diff --git a/examples/assets.json b/examples/assets.json
index aa81661..222cb04 100644
--- a/examples/assets.json
+++ b/examples/assets.json
@@ -86,5 +86,9 @@
   "cat.spz": {
     "url": "https://forge-gfx.github.io/assets/splats/cat.spz",
     "directory": "splats"
+  },
+  "arrow.glb": {
+    "url": "https://forge-gfx.github.io/assets/models/arrow.glb",
+    "directory": "models"
   }
 }
diff --git a/examples/multiple-viewpoints/index.html b/examples/multiple-viewpoints/index.html
index e247604..63684c1 100644
--- a/examples/multiple-viewpoints/index.html
+++ b/examples/multiple-viewpoints/index.html
@@ -1,10 +1,34 @@
 <!DOCTYPE html>
+
 <head>
   <meta charset="utf-8">
   <title>Forge • Multiple Viewpoints</title>
-  <style> body {margin: 0;} </style>
+  <style>
+    body {
+      margin: 0;
+      background-color: black;
+    }
+
+    header {
+      margin: 0 auto;
+      padding: 10px 0;
+      min-width: 400px;
+      width: 50%;
+    }
+
+    input {
+      width: 100%;
+      padding: 10px 0;
+    }
+  </style>
 </head>
+
 <body>
+  <header>
+    <input type="range" min="-100" max="100" id="camera1">
+    <input type="range" min="-100" max="100" id="camera2">
+  </header>
+
   <script type="importmap">
     {
       "imports": {
@@ -16,25 +40,27 @@
   <script type="module">
     import * as THREE from "three";
     import { ForgeRenderer, ForgeViewpoint, SplatMesh } from "@forge-gfx/forge";
+    import { GLTFLoader } from 'three/addons/loaders/GLTFLoader.js';
     import { getAssetFileURL } from "/examples/js/get-asset-url.js";
 
     const scene = new THREE.Scene();
     scene.background = new THREE.Color(0x000000);
     const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
     const renderer = new THREE.WebGLRenderer();
-    renderer.setSize(window.innerWidth, window.innerHeight);
+    const header_height = document.querySelector('header').getBoundingClientRect().height;
+    renderer.setSize(window.innerWidth, window.innerHeight - header_height);
     document.body.appendChild(renderer.domElement)
 
     // Explicitly create a ForgeRenderer in the scene to spawn new viewpoints
     const forge = new ForgeRenderer({ renderer });
 
     const splatURL = await getAssetFileURL("butterfly.spz");
-    const butterfly = new SplatMesh({ url: splatURL});
+    const butterfly = new SplatMesh({ url: splatURL });
     butterfly.quaternion.set(1, 0, 0, 0);
-    butterfly.position.set(0, 0, -1);
+    butterfly.position.set(0, 0, -3);
     scene.add(butterfly);
 
-    function createViewpoint(origin, screenPos) {
+    async function createViewpoint(origin, screenPos, index) {
       // Create a textured rectangle at the near plane to show the viewpoint
       const width = 320;
       const height = 240;
@@ -49,15 +75,30 @@
       viewCamera.position.copy(origin);
       viewCamera.lookAt(butterfly.position);
 
-      // Create a cone to show the viewpoint camera
-      const cone = new THREE.Mesh(
-        new THREE.ConeGeometry(0.1, 0.1, 32),
-        new THREE.MeshNormalMaterial(),
-      );
-      cone.position.copy(viewCamera.position);
-      cone.quaternion.copy(viewCamera.quaternion);
-      cone.rotateX(Math.PI / 2);
-      scene.add(cone);
+      // Load arrow object to show where each camera is
+      const arrowURL = await getAssetFileURL("arrow.glb");
+      new GLTFLoader().load(arrowURL, gltf => {
+        // Different material for each camera
+        const arrowMaterial = new THREE.MeshMatcapMaterial({
+          matcap: [
+            new THREE.TextureLoader().load("https://raw.githubusercontent.com/nidorx/matcaps/master/128/1A2461_3D70DB_2C3C8F_2C6CAC-128px.png"),
+            new THREE.TextureLoader().load("https://raw.githubusercontent.com/nidorx/matcaps/master/128/9D282A_38191D_DFC6CD_D6495A-128px.png")
+          ][index]
+        });
+
+        const arrow = gltf.scene.children[0];
+        arrow.material = arrowMaterial;
+        arrow.position.copy(viewCamera.position);
+        arrow.lookAt(butterfly.position);
+        scene.add(arrow);
+
+        // Connect slider to both camera and arrow
+        document.getElementById("camera" + (index + 1)).oninput = ev => {
+          viewCamera.position.x = (ev.target.value / 100);
+          arrow.position.x = viewCamera.position.x;
+          arrow.lookAt(butterfly.position);
+        };
+      });
 
       // Spawn a new viewpoint that auto-updates its sort order, double
       // buffered in case the texture is used recursively in the scene
@@ -74,8 +115,8 @@
     }
 
     const viewpoints = [
-      createViewpoint(new THREE.Vector3(0, 0.5, -1), new THREE.Vector2(-0.5, 0.5)),
-      createViewpoint(new THREE.Vector3(0.5, -0.5, -1), new THREE.Vector2(-0.5, -0.5)),
+      createViewpoint(new THREE.Vector3(0, 1.5, -3), new THREE.Vector2(-0.5, 0.5), 0),
+      createViewpoint(new THREE.Vector3(0.5, -1, -3), new THREE.Vector2(0.5, -0.5), 1),
     ];
 
     renderer.setAnimationLoop(function animate(time) {
@@ -83,12 +124,13 @@
       renderer.render(scene, camera);
       butterfly.rotation.y += 0.01;
 
-      // Adjust the background for visibility and render the viewpoints
-      scene.background.set(0x000040);
-      for (const viewpoint of viewpoints) {
-        viewpoint.renderTarget({ scene, camera: viewpoint.camera });
+      // Render each viewpoint (with a different background each)
+      for (let i = 0; i < viewpoints.length; i++) {
+        scene.background.set([0x202040, 0x302020][i]);
+        viewpoints[i].renderTarget({ scene, camera: viewpoints[i].camera });
       }
     });
   </script>
 </body>
+
 </html>

From e0123e52c8105c962769db2b5d44e2a54086fd8b Mon Sep 17 00:00:00 2001
From: "Diego F. Goberna" <github@feiss.be>
Date: Sun, 25 May 2025 21:07:27 +0200
Subject: [PATCH 2/2] fix async

---
 examples/multiple-viewpoints/index.html | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/examples/multiple-viewpoints/index.html b/examples/multiple-viewpoints/index.html
index 63684c1..0e3b2ac 100644
--- a/examples/multiple-viewpoints/index.html
+++ b/examples/multiple-viewpoints/index.html
@@ -111,12 +111,13 @@
           screen.material.map = texture;
         },
       });
+
       return viewpoint;
     }
 
     const viewpoints = [
-      createViewpoint(new THREE.Vector3(0, 1.5, -3), new THREE.Vector2(-0.5, 0.5), 0),
-      createViewpoint(new THREE.Vector3(0.5, -1, -3), new THREE.Vector2(0.5, -0.5), 1),
+      await createViewpoint(new THREE.Vector3(0, 1.5, -3), new THREE.Vector2(-0.5, 0.5), 0),
+      await createViewpoint(new THREE.Vector3(0.5, -1, -3), new THREE.Vector2(0.5, -0.5), 1),
     ];
 
     renderer.setAnimationLoop(function animate(time) {