Texture: Introduce `pmremVersion` (#27963)

src/renderers/webgl/WebGLCubeUVMaps.js

@@ -20,24 +20,26 @@ function WebGLCubeUVMaps( renderer ) {
 
 			if ( isEquirectMap || isCubeMap ) {
 
-				if ( texture.isRenderTargetTexture && texture.needsPMREMUpdate === true ) {
+				let renderTarget = cubeUVmaps.get( texture );
 
-					texture.needsPMREMUpdate = false;
+				const currentPMREMVersion = renderTarget !== undefined ? renderTarget.texture.pmremVersion : 0;
 
-					let renderTarget = cubeUVmaps.get( texture );
+				if ( texture.isRenderTargetTexture && texture.pmremVersion !== currentPMREMVersion ) {
 
 					if ( pmremGenerator === null ) pmremGenerator = new PMREMGenerator( renderer );
 
 					renderTarget = isEquirectMap ? pmremGenerator.fromEquirectangular( texture, renderTarget ) : pmremGenerator.fromCubemap( texture, renderTarget );
+					renderTarget.texture.pmremVersion = texture.pmremVersion;
+
 					cubeUVmaps.set( texture, renderTarget );
 
 					return renderTarget.texture;
 
 				} else {
 
-					if ( cubeUVmaps.has( texture ) ) {
+					if ( renderTarget !== undefined ) {
 
-						return cubeUVmaps.get( texture ).texture;
+						return renderTarget.texture;
 
 					} else {
 
@@ -47,7 +49,9 @@ function WebGLCubeUVMaps( renderer ) {
 
 							if ( pmremGenerator === null ) pmremGenerator = new PMREMGenerator( renderer );
 
-							const renderTarget = isEquirectMap ? pmremGenerator.fromEquirectangular( texture ) : pmremGenerator.fromCubemap( texture );
+							renderTarget = isEquirectMap ? pmremGenerator.fromEquirectangular( texture ) : pmremGenerator.fromCubemap( texture );
+							renderTarget.texture.pmremVersion = texture.pmremVersion;
+
 							cubeUVmaps.set( texture, renderTarget );
 
 							texture.addEventListener( 'dispose', onTextureDispose );

src/textures/Texture.js

@@ -70,7 +70,7 @@ class Texture extends EventDispatcher {
 		this.onUpdate = null;
 
 		this.isRenderTargetTexture = false; // indicates whether a texture belongs to a render target or not
-		this.needsPMREMUpdate = false; // indicates whether this texture should be processed by PMREMGenerator or not (only relevant for render target textures)
+		this.pmremVersion = 0; // indicates whether this texture should be processed by PMREMGenerator or not (only relevant for render target textures)
 
 	}
 
@@ -301,6 +301,16 @@ class Texture extends EventDispatcher {
 
 	}
 
+	set needsPMREMUpdate( value ) {
+
+		if ( value === true ) {
+
+			this.pmremVersion ++;
+
+		}
+
+	}
+
 }
 
 Texture.DEFAULT_IMAGE = null;