From 7b31083d56bfa14347c89a480b1995f89631737e Mon Sep 17 00:00:00 2001
From: Christian Helgeson <62450112+cmhhelgeson@users.noreply.github.com>
Date: Wed, 4 Jun 2025 01:43:33 -0700
Subject: [PATCH] NodeBuilder - Fix Interpolation (#31222)

* init branch

* fix

* remove comment

* Update GLSLNodeBuilder.js

Clean up.

---------

Co-authored-by: Michael Herzog <michael.herzog@human-interactive.org>
---
 examples/webgpu_centroid_sampling.html               | 12 ++++++------
 src/constants.js                                     |  4 ++--
 .../webgl-fallback/nodes/GLSLNodeBuilder.js          |  4 +---
 3 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/examples/webgpu_centroid_sampling.html b/examples/webgpu_centroid_sampling.html
index d22aabffe63fe1..f562353ee36bde 100644
--- a/examples/webgpu_centroid_sampling.html
+++ b/examples/webgpu_centroid_sampling.html
@@ -158,8 +158,8 @@
 
 				};
 
-				const withFlatFirstShader = createShader( THREE.InterpolationSamplingType.FLAT, THREE.InterpolationSamplingMode.FLAT_FIRST );
-				const withFlatEitherShader = createShader( THREE.InterpolationSamplingType.FLAT, THREE.InterpolationSamplingMode.FLAT_EITHER );
+				const withFlatFirstShader = createShader( THREE.InterpolationSamplingType.FLAT, THREE.InterpolationSamplingMode.FIRST );
+				const withFlatEitherShader = createShader( THREE.InterpolationSamplingType.FLAT, THREE.InterpolationSamplingMode.EITHER );
 
 				const withSampleShader = Fn( () => {
 
@@ -235,16 +235,16 @@
 					THREE.InterpolationSamplingMode.NORMAL,
 					THREE.InterpolationSamplingMode.CENTROID,
 					THREE.InterpolationSamplingMode.SAMPLE,
-					THREE.InterpolationSamplingMode.FLAT_FIRST,
-					THREE.InterpolationSamplingMode.FLAT_EITHER
+					'flat first',
+					'flat either'
 				] ).onChange( () => {
 
 					const interpolationShaderLib = {
 						[ THREE.InterpolationSamplingMode.NORMAL ]: withoutInterpolationShader,
 						[ THREE.InterpolationSamplingMode.CENTROID ]: withInterpolationShader,
 						[ THREE.InterpolationSamplingMode.SAMPLE ]: withSampleShader,
-						[ THREE.InterpolationSamplingMode.FLAT_FIRST ]: withFlatFirstShader,
-						[ THREE.InterpolationSamplingMode.FLAT_EITHER ]: withFlatEitherShader
+						[ 'flat first' ]: withFlatFirstShader,
+						[ 'flat either' ]: withFlatEitherShader
 					};
 
 					const shader = interpolationShaderLib[ effectController.sampling ];
diff --git a/src/constants.js b/src/constants.js
index 77bc2613c0583d..7a6334e3870b7e 100644
--- a/src/constants.js
+++ b/src/constants.js
@@ -1612,8 +1612,8 @@ export const InterpolationSamplingMode = {
 	NORMAL: 'normal',
 	CENTROID: 'centroid',
 	SAMPLE: 'sample',
-	FLAT_FIRST: 'flat first',
-	FLAT_EITHER: 'flat either'
+	FIRST: 'first',
+	EITHER: 'either'
 };
 
 /**
diff --git a/src/renderers/webgl-fallback/nodes/GLSLNodeBuilder.js b/src/renderers/webgl-fallback/nodes/GLSLNodeBuilder.js
index da2f96f8911a88..226d5d29c1599a 100644
--- a/src/renderers/webgl-fallback/nodes/GLSLNodeBuilder.js
+++ b/src/renderers/webgl-fallback/nodes/GLSLNodeBuilder.js
@@ -30,9 +30,7 @@ const interpolationTypeMap = {
 };
 
 const interpolationModeMap = {
-	'centroid': 'centroid',
-	'flat first': 'flat',
-	'flat either': 'flat'
+	'centroid': 'centroid'
 };
 
 const defaultPrecisions = `