Add custom shadow generator support

src/Lights/Shadows/babylon.shadowGenerator.ts

@@ -1,5 +1,11 @@
 module BABYLON {
-    export class ShadowGenerator {
+    export interface IShadowGenerator {
+        getShadowMap(): RenderTargetTexture;
+
+        dispose(): void;
+    }
+
+    export class ShadowGenerator implements IShadowGenerator {
         private static _FILTER_NONE = 0;
         private static _FILTER_VARIANCESHADOWMAP = 1;
         private static _FILTER_POISSONSAMPLING = 2;

src/Lights/babylon.light.ts

@@ -17,7 +17,7 @@
 
         getShadowDirection(faceIndex?: number): Vector3;
 
-        _shadowGenerator: ShadowGenerator;
+        _shadowGenerator: IShadowGenerator;
     }
 
     export class Light extends Node {
@@ -46,7 +46,7 @@
         @serialize()
         public radius = 0.00001;
 
-        public _shadowGenerator: ShadowGenerator;
+        public _shadowGenerator: IShadowGenerator;
         private _parentedWorldMatrix: Matrix;
         public _excludedMeshesIds = new Array<string>();
         public _includedOnlyMeshesIds = new Array<string>();
@@ -73,7 +73,7 @@
             return ret;
         } 
         
-        public getShadowGenerator(): ShadowGenerator {
+        public getShadowGenerator(): IShadowGenerator {
             return this._shadowGenerator;
         }
 

src/Materials/babylon.materialHelper.ts

@@ -74,7 +74,7 @@
 
                 // Shadows
                 if (scene.shadowsEnabled) {
-                    var shadowGenerator = light.getShadowGenerator();
+                    var shadowGenerator = <ShadowGenerator>light.getShadowGenerator();
                     if (mesh && mesh.receiveShadows && shadowGenerator) {
                         if (defines["SHADOW" + lightIndex] === undefined) {
                             needRebuild = true;
@@ -191,7 +191,7 @@
 
         // Bindings
         public static BindLightShadow(light: Light, scene: Scene, mesh: AbstractMesh, lightIndex: number, effect: Effect, depthValuesAlreadySet: boolean): boolean {
-            var shadowGenerator = light.getShadowGenerator();
+            var shadowGenerator = <ShadowGenerator>light.getShadowGenerator();
             if (mesh.receiveShadows && shadowGenerator) {
                 if (!(<any>light).needCube()) {
                     effect.setMatrix("lightMatrix" + lightIndex, shadowGenerator.getTransformMatrix());

src/Tools/babylon.sceneSerializer.ts

@@ -334,8 +334,10 @@
             for (index = 0; index < scene.lights.length; index++) {
                 light = scene.lights[index];
 
-                if (light.getShadowGenerator()) {
-                    serializationObject.shadowGenerators.push(light.getShadowGenerator().serialize());
+                let shadowGenerator = light.getShadowGenerator();
+                // Only support serialization for official generator so far.
+                if (shadowGenerator && shadowGenerator instanceof ShadowGenerator) {
+                    serializationObject.shadowGenerators.push(<ShadowGenerator>shadowGenerator.serialize());
                 }
             }