Updated builds.

build/three.js

@@ -14602,6 +14602,10 @@
 
 		var planeMesh;
 		var boxMesh;
+		// Store the current background texture and its `version`
+		// so we can recompile the material accordingly.
+		var currentBackground = null;
+		var currentBackgroundVersion = 0;
 
 		function render( renderList, scene, camera, forceClear ) {
 
@@ -14610,11 +14614,15 @@
 			if ( background === null ) {
 
 				setClear( clearColor, clearAlpha );
+				currentBackground = null;
+				currentBackgroundVersion = 0;
 
 			} else if ( background && background.isColor ) {
 
 				setClear( background, 1 );
 				forceClear = true;
+				currentBackground = null;
+				currentBackgroundVersion = 0;
 
 			}
 
@@ -14666,9 +14674,20 @@
 
 				}
 
-				boxMesh.material.uniforms.tCube.value = ( background.isWebGLRenderTargetCube ) ? background.texture : background;
+				var texture = background.isWebGLRenderTargetCube ? background.texture : background;
+				boxMesh.material.uniforms.tCube.value = texture;
 				boxMesh.material.uniforms.tFlip.value = ( background.isWebGLRenderTargetCube ) ? 1 : - 1;
 
+				if ( currentBackground !== background ||
+				     currentBackgroundVersion !== texture.version ) {
+
+					boxMesh.material.needsUpdate = true;
+
+					currentBackground = background;
+					currentBackgroundVersion = texture.version;
+
+				}
+
 				// push to the pre-sorted opaque render list
 				renderList.push( boxMesh, boxMesh.geometry, boxMesh.material, 0, null );
 
@@ -14717,6 +14736,17 @@
 
 				planeMesh.material.uniforms.uvTransform.value.copy( background.matrix );
 
+				if ( currentBackground !== background ||
+					   currentBackgroundVersion !== background.version ) {
+
+					planeMesh.material.needsUpdate = true;
+
+					currentBackground = background;
+					currentBackgroundVersion = background.version;
+
+				}
+
+
 				// push to the pre-sorted opaque render list
 				renderList.push( planeMesh, planeMesh.geometry, planeMesh.material, 0, null );
 

build/three.module.js

@@ -14596,6 +14596,10 @@ function WebGLBackground( renderer, state, objects, premultipliedAlpha ) {
 
 	var planeMesh;
 	var boxMesh;
+	// Store the current background texture and its `version`
+	// so we can recompile the material accordingly.
+	var currentBackground = null;
+	var currentBackgroundVersion = 0;
 
 	function render( renderList, scene, camera, forceClear ) {
 
@@ -14604,11 +14608,15 @@ function WebGLBackground( renderer, state, objects, premultipliedAlpha ) {
 		if ( background === null ) {
 
 			setClear( clearColor, clearAlpha );
+			currentBackground = null;
+			currentBackgroundVersion = 0;
 
 		} else if ( background && background.isColor ) {
 
 			setClear( background, 1 );
 			forceClear = true;
+			currentBackground = null;
+			currentBackgroundVersion = 0;
 
 		}
 
@@ -14660,9 +14668,20 @@ function WebGLBackground( renderer, state, objects, premultipliedAlpha ) {
 
 			}
 
-			boxMesh.material.uniforms.tCube.value = ( background.isWebGLRenderTargetCube ) ? background.texture : background;
+			var texture = background.isWebGLRenderTargetCube ? background.texture : background;
+			boxMesh.material.uniforms.tCube.value = texture;
 			boxMesh.material.uniforms.tFlip.value = ( background.isWebGLRenderTargetCube ) ? 1 : - 1;
 
+			if ( currentBackground !== background ||
+			     currentBackgroundVersion !== texture.version ) {
+
+				boxMesh.material.needsUpdate = true;
+
+				currentBackground = background;
+				currentBackgroundVersion = texture.version;
+
+			}
+
 			// push to the pre-sorted opaque render list
 			renderList.push( boxMesh, boxMesh.geometry, boxMesh.material, 0, null );
 
@@ -14711,6 +14730,17 @@ function WebGLBackground( renderer, state, objects, premultipliedAlpha ) {
 
 			planeMesh.material.uniforms.uvTransform.value.copy( background.matrix );
 
+			if ( currentBackground !== background ||
+				   currentBackgroundVersion !== background.version ) {
+
+				planeMesh.material.needsUpdate = true;
+
+				currentBackground = background;
+				currentBackgroundVersion = background.version;
+
+			}
+
+
 			// push to the pre-sorted opaque render list
 			renderList.push( planeMesh, planeMesh.geometry, planeMesh.material, 0, null );