Merge pull request #4448 from jbousquie/fix.SPS.updatable.option

SPS updatable parameter setting fix

dist/preview release/what's new.md

@@ -68,6 +68,7 @@
 - Fixed a bug with setting `unlit` on `PBRMaterial` after the material is ready (Wrong dirty flags) ([bghgary](http://www.github.com/bghgary))
 - Fixed `HighlightLayer` support on browsers not supporting HalfFloat ([sebavan](http://www.github.com/sebavan))
 - Fixed support for R and RG texture formats ([sebavan](http://www.github.com/sebavan))
+- Fixed `updatable` parameter setting in the SPS ([jerome](https://github.com/jbousquie))
 
 ### Viewer
 

src/Particles/babylon.solidParticleSystem.ts

@@ -159,7 +159,7 @@
                 this._particlesIntersect = options ? <boolean>options.particleIntersection : false;
                 this._bSphereOnly= options ? <boolean>options.boundingSphereOnly : false;
                 this._bSphereRadiusFactor = (options && options.bSphereRadiusFactor) ? options.bSphereRadiusFactor : 1.0;
-                if (options && options.updatable) {
+                if (options && options.updatable !== undefined) {
                     this._updatable = options.updatable;
                 } else {
                     this._updatable = true;