From 500475c3108950b518e16491585c7fef91d06a3c Mon Sep 17 00:00:00 2001
From: Will Eastcott <will@playcanvas.com>
Date: Wed, 28 Aug 2024 20:08:14 +0100
Subject: [PATCH] Fix 3D Gaussian Splat rendering in VR (#6896)

---
 src/scene/gsplat/gsplat-instance.js | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/scene/gsplat/gsplat-instance.js b/src/scene/gsplat/gsplat-instance.js
index aff797406dd..2ffbc1e04e3 100644
--- a/src/scene/gsplat/gsplat-instance.js
+++ b/src/scene/gsplat/gsplat-instance.js
@@ -166,6 +166,16 @@ class GSplatInstance {
         const device = this.splat.device;
         viewport[0] = device.width;
         viewport[1] = device.height;
+
+        // adjust viewport for stereoscopic VR sessions
+        if (this.cameras.length > 0) {
+            const camera = this.cameras[0];
+            const xr = camera.xr;
+            if (xr && xr.active && xr.views.list.length === 2) {
+                viewport[0] /= 2;
+            }
+        }
+
         this.material.setParameter('viewport', viewport);
     }