From 2b80e6a57c052d21715b1f29868855667a27b550 Mon Sep 17 00:00:00 2001
From: Jure Triglav <juretriglav@gmail.com>
Date: Sat, 27 Jun 2026 19:34:30 +0200
Subject: [PATCH] TSL: Restore instanced matrix buffer capacity (#33889)

---
 src/nodes/accessors/Instance.js              | 33 ++++++++------------
 test/unit/src/objects/InstancedMesh.tests.js |  1 -
 2 files changed, 13 insertions(+), 21 deletions(-)

diff --git a/src/nodes/accessors/Instance.js b/src/nodes/accessors/Instance.js
index b9dbe74da72e07..b89834b9166c75 100644
--- a/src/nodes/accessors/Instance.js
+++ b/src/nodes/accessors/Instance.js
@@ -23,26 +23,26 @@ const _previousInstanceMatrices = /*@__PURE__*/ new WeakMap();
  *
  * @param {NodeBuilder} builder - The current node builder.
  * @param {InstancedBufferAttribute|StorageInstancedBufferAttribute} instanceMatrix - The matrix buffer attribute.
- * @param {number} count - The instance count.
  * @returns {Node} The matrix node.
  */
-function createInstanceMatrixNode( builder, instanceMatrix, count ) {
+function createInstanceMatrixNode( builder, instanceMatrix ) {
 
 	let instanceMatrixNode;
+	const matrixCount = Math.max( instanceMatrix.count, 1 );
 
 	const isStorageMatrix = instanceMatrix.isStorageInstancedBufferAttribute === true;
 
 	if ( isStorageMatrix ) {
 
-		instanceMatrixNode = storage( instanceMatrix, 'mat4', Math.max( count, 1 ) ).element( instanceIndex );
+		instanceMatrixNode = storage( instanceMatrix, 'mat4', matrixCount ).element( instanceIndex );
 
 	} else {
 
-		const uniformBufferSize = count * 16 * 4;
+		const uniformBufferSize = matrixCount * 16 * 4;
 
 		if ( uniformBufferSize <= builder.getUniformBufferLimit() ) {
 
-			instanceMatrixNode = buffer( instanceMatrix.array, 'mat4', Math.max( count, 1 ) ).element( instanceIndex );
+			instanceMatrixNode = buffer( instanceMatrix.array, 'mat4', matrixCount ).element( instanceIndex );
 
 		} else {
 
@@ -81,10 +81,9 @@ function createInstanceMatrixNode( builder, instanceMatrix, count ) {
  * @param {InstancedMesh} instancedMesh - The instanced mesh object.
  * @param {InstancedBufferAttribute|StorageInstancedBufferAttribute} instanceMatrix - The current matrix buffer attribute.
  * @param {NodeBuilder} builder - The current node builder.
- * @param {number} count - The instance count.
  * @returns {Node} The previous frame instance matrix node.
  */
-function getPreviousInstance( instancedMesh, instanceMatrix, builder, count ) {
+function getPreviousInstance( instancedMesh, instanceMatrix, builder ) {
 
 	let data = _previousInstanceMatrices.get( instancedMesh );
 
@@ -94,7 +93,7 @@ function getPreviousInstance( instancedMesh, instanceMatrix, builder, count ) {
 
 		data = {
 			previousInstanceMatrix,
-			node: createInstanceMatrixNode( builder, previousInstanceMatrix, count )
+			node: createInstanceMatrixNode( builder, previousInstanceMatrix )
 		};
 
 		_previousInstanceMatrices.set( instancedMesh, data );
@@ -118,26 +117,22 @@ export const instanceColor = /*@__PURE__*/ varyingProperty( 'vec3', 'vInstanceCo
  *
  * @tsl
  * @function
- * @param {number} count - The instance count.
  * @param {InstancedBufferAttribute|StorageInstancedBufferAttribute} matrices - The instanced transformation matrices.
  * @param {?InstancedBufferAttribute|StorageInstancedBufferAttribute} [colors=null] - The optional instanced colors.
  */
-export const instance = /*@__PURE__*/ Fn( ( [ count, matrices, colors = null ], builder ) => {
-
-	// get numeric value (non-node)
-	count = count.value;
+export const instance = /*@__PURE__*/ Fn( ( [ matrices, colors = null ], builder ) => {
 
 	const isStorageMatrix = matrices.isStorageInstancedBufferAttribute === true;
 	const isStorageColor = colors && colors.isStorageInstancedBufferAttribute === true;
 
-	const instanceMatrixNode = createInstanceMatrixNode( builder, matrices, count );
+	const instanceMatrixNode = createInstanceMatrixNode( builder, matrices );
 
 	// interleaved buffer tracking for matrix
 	let interleavedMatrix = null;
 
 	if ( ! isStorageMatrix ) {
 
-		const uniformBufferSize = count * 16 * 4;
+		const uniformBufferSize = Math.max( matrices.count, 1 ) * 16 * 4;
 
 		if ( uniformBufferSize > builder.getUniformBufferLimit() ) {
 
@@ -229,7 +224,7 @@ export const instance = /*@__PURE__*/ Fn( ( [ count, matrices, colors = null ],
 
 		} );
 
-		const previousInstanceMatrixNode = getPreviousInstance( instancedMesh, matrices, builder, count );
+		const previousInstanceMatrixNode = getPreviousInstance( instancedMesh, matrices, builder );
 		positionPrevious.assign( previousInstanceMatrixNode.mul( positionPrevious ).xyz );
 
 	}
@@ -262,10 +257,8 @@ export const instance = /*@__PURE__*/ Fn( ( [ count, matrices, colors = null ],
  */
 export const instancedMesh = /*@__PURE__*/ Fn( ( [ instancedMesh ] ) => {
 
-	const { count, instanceMatrix, instanceColor } = instancedMesh;
+	const { instanceMatrix, instanceColor } = instancedMesh;
 
-	instance( count, instanceMatrix, instanceColor );
+	instance( instanceMatrix, instanceColor );
 
 }, 'void' );
-
-
diff --git a/test/unit/src/objects/InstancedMesh.tests.js b/test/unit/src/objects/InstancedMesh.tests.js
index 192870c200820e..12661730212f3f 100644
--- a/test/unit/src/objects/InstancedMesh.tests.js
+++ b/test/unit/src/objects/InstancedMesh.tests.js
@@ -1,5 +1,4 @@
 import { InstancedMesh } from '../../../../src/objects/InstancedMesh.js';
-
 import { Mesh } from '../../../../src/objects/Mesh.js';
 
 export default QUnit.module( 'Objects', () => {