Add method to update existing post process instead of creating a new one

src/Materials/Node/nodeMaterial.ts

@@ -748,7 +748,20 @@ export class NodeMaterial extends PushMaterial {
     public createPostProcess(
         camera: Nullable<Camera>, options: number | PostProcessOptions = 1, samplingMode: number = Constants.TEXTURE_NEAREST_SAMPLINGMODE, engine?: Engine, reusable?: boolean,
         textureType: number = Constants.TEXTURETYPE_UNSIGNED_INT, textureFormat = Constants.TEXTUREFORMAT_RGBA): PostProcess {
+            return this._createEffectOrPostProcess(null, camera, options, samplingMode, engine, reusable, textureType, textureFormat);
+    }
+
+    /**
+     * Create the post process effect from the material
+     * @param postProcess The post process to create the effect for
+     */
+    public createEffectForPostProcess(postProcess: PostProcess) {
+        this._createEffectOrPostProcess(postProcess);
+    }
 
+    private _createEffectOrPostProcess(postProcess: Nullable<PostProcess>,
+        camera?: Nullable<Camera>, options: number | PostProcessOptions = 1, samplingMode: number = Constants.TEXTURE_NEAREST_SAMPLINGMODE, engine?: Engine, reusable?: boolean,
+        textureType: number = Constants.TEXTURETYPE_UNSIGNED_INT, textureFormat = Constants.TEXTUREFORMAT_RGBA): PostProcess {
         let tempName = this.name + this._buildId;
 
         const defines = new NodeMaterialDefines();
@@ -761,10 +774,14 @@ export class NodeMaterial extends PushMaterial {
 
         Effect.RegisterShader(tempName, this._fragmentCompilationState._builtCompilationString, this._vertexCompilationState._builtCompilationString);
 
-        const postProcess = new PostProcess(
-            this.name + "PostProcess", tempName, this._fragmentCompilationState.uniforms, this._fragmentCompilationState.samplers,
-            options, camera, samplingMode, engine, reusable, defines.toString(), textureType, tempName, { maxSimultaneousLights: this.maxSimultaneousLights }, false, textureFormat
-        );
+        if (!postProcess) {
+            postProcess = new PostProcess(
+                this.name + "PostProcess", tempName, this._fragmentCompilationState.uniforms, this._fragmentCompilationState.samplers,
+                options, camera!, samplingMode, engine, reusable, defines.toString(), textureType, tempName, { maxSimultaneousLights: this.maxSimultaneousLights }, false, textureFormat
+            );
+        } else {
+            postProcess.updateEffect(defines.toString(), this._fragmentCompilationState.uniforms, this._fragmentCompilationState.samplers, { maxSimultaneousLights: this.maxSimultaneousLights }, undefined, undefined, tempName, tempName);
+        }
 
         postProcess.nodeMaterialSource = this;