Add deck instance to layer context (#2805)

docs/api-reference/layer.md

@@ -344,6 +344,7 @@ The context object stores information that are shared by all layers.
 
 * `gl` ([WebGLRenderingContext](https://developer.mozilla.org/en-US/docs/Web/API/WebGLRenderingContext)) - WebGL context of the current canvas.
 * `viewport` ([Viewport](/docs/api-reference/viewport.md)) - The current viewport
+* `deck` ([Deck](/docs/api-reference/deck.md)) - The current deck.gl instance
 
 ##### `state` (Object)
 

modules/core/src/lib/deck.js

@@ -528,6 +528,7 @@ export default class Deck {
     const viewport = this.viewManager.getViewports()[0];
     // Note: avoid React setState due GL animation loop / setState timing issue
     this.layerManager = new LayerManager(gl, {
+      deck: this,
       stats: this.stats,
       viewport
     });

modules/core/src/lib/layer-manager.js

@@ -43,6 +43,7 @@ const LOG_PRIORITY_LIFECYCLE_MINOR = 4;
 // CONTEXT IS EXPOSED TO LAYERS
 const INITIAL_CONTEXT = Object.seal({
   layerManager: null,
+  deck: null,
   gl: null,
 
   // Settings
@@ -64,7 +65,7 @@ const layerName = layer => (layer instanceof Layer ? `${layer}` : !layer ? 'null
 
 export default class LayerManager {
   // eslint-disable-next-line
-  constructor(gl, {stats, viewport = null} = {}) {
+  constructor(gl, {deck, stats, viewport = null} = {}) {
     // Currently deck.gl expects the DeckGL.layers array to be different
     // whenever React rerenders. If the same layers array is used, the
     // LayerManager's diffing algorithm will generate a fatal error and
@@ -79,7 +80,7 @@ export default class LayerManager {
 
     this.context = Object.assign({}, INITIAL_CONTEXT, {
       layerManager: this,
-
+      deck,
       gl,
       // Enabling luma.gl Program caching using private API (_cachePrograms)
       shaderCache: gl && new ShaderCache({gl, _cachePrograms: true}),