From 302c62fd8888481c7a989a1697e3c47ad2353864 Mon Sep 17 00:00:00 2001
From: WestLangley <WestLangley@users.noreply.github.com>
Date: Thu, 23 Jul 2026 14:02:17 -0400
Subject: [PATCH] Examples: Eliminate branch divergence in volume refinement
 loops. (#34097)

---
 examples/webgl_volume_perlin.html  | 13 +++----------
 examples/webgpu_volume_perlin.html | 13 ++++---------
 2 files changed, 7 insertions(+), 19 deletions(-)

diff --git a/examples/webgl_volume_perlin.html b/examples/webgl_volume_perlin.html
index b58e6d19ec5340..e81c8272164e11 100644
--- a/examples/webgl_volume_perlin.html
+++ b/examples/webgl_volume_perlin.html
@@ -195,18 +195,11 @@
 									for ( int j = 0; j < REFINEMENT_STEPS; j ++ ) {
 
 										float tm = ( t0 + t1 ) * 0.5;
-
 										float dm = sample1( vOrigin + tm * rayDir + 0.5 );
 
-										if ( dm > threshold ) {
-
-											t1 = tm;
-
-										} else {
-
-											t0 = tm;
-
-										}
+										bool isGreater = dm > threshold;
+										t1 = isGreater ? tm : t1;
+										t0 = isGreater ? t0 : tm;
 
 									}
 
diff --git a/examples/webgpu_volume_perlin.html b/examples/webgpu_volume_perlin.html
index 1790757bdb8e17..f0e53ffd5c6220 100644
--- a/examples/webgpu_volume_perlin.html
+++ b/examples/webgpu_volume_perlin.html
@@ -37,7 +37,7 @@
 		<script type="module">
 
 			import * as THREE from 'three/webgpu';
-			import { Break, If, Loop, bool, vec3, vec4, texture3D, uniform, Fn } from 'three/tsl';
+			import { Break, If, Loop, select, bool, vec3, vec4, texture3D, uniform, Fn } from 'three/tsl';
 
 			import { RaymarchingBox } from 'three/addons/tsl/utils/Raymarching.js';
 
@@ -134,15 +134,10 @@
 									const pm = p0.add( p1 ).mul( 0.5 ).toConst();
 									const dm = texture.sample( pm.add( 0.5 ) ).r.toConst();
 
-									If( dm.greaterThan( threshold ), () => {
+									const isGreater = dm.greaterThan( threshold );
 
-										p1.assign( pm );
-
-									} ).Else( () => {
-
-										p0.assign( pm );
-
-									} );
+									p1.assign( select( isGreater, pm, p1 ).uniformFlow() );
+									p0.assign( select( isGreater, p0, pm ).uniformFlow() );
 
 								} );