Simplify headless context handling

modules/webgl/src/context/create-headless-context.js

@@ -1,11 +1,14 @@
-import {headlessGL} from '../webgl-utils/webgl-types';
-
 const ERR_HEADLESSGL_NOT_AVAILABLE =
   'Failed to create WebGL context in Node.js, headless gl not available';
 
 const ERR_HEADLESSGL_FAILED =
   'Failed to create WebGL context in Node.js, headless gl returned null';
 
+const ERR_HEADLESSGL_LOAD = `\
+  luma.gl: loaded under Node.js without headless gl installed, meaning that WebGL \
+  contexts can not be created. This may not be an error. For example, this is a \
+  typical configuration for isorender applications running on the server.`;
+
 // Create headless gl context (for running under Node.js)
 export function createHeadlessContext(options) {
   const {width, height, webgl1, webgl2, onError} = options;
@@ -21,3 +24,26 @@ export function createHeadlessContext(options) {
   }
   return gl;
 }
+
+// TODO(Tarek): OOGLY HACK to avoid webpack requiring headless
+//   browser bundles. Will be removed in 8.0 when we
+//   remove automatic headless context creation
+// NOTE: Rollup does not process the line `const m = module;`
+//   and writes it out verbatim in its final output, which ends
+//   up falling over in browser environments at runtime. Added
+//   a `try/catch` block to fix usage in rollup builds.
+let m;
+try {
+  m = module;
+} catch (e) {
+  m = null;
+}
+
+// Load headless gl dynamically, if available
+function headlessGL(...args) {
+  const headless = m.require('gl');
+  if (!headless) {
+    throw new Error(ERR_HEADLESSGL_LOAD);
+  }
+  return headless(...args);
+}

modules/webgl/src/init.js

@@ -62,6 +62,16 @@ if (!global.luma) {
   };
 }
 
+// Ensures that WebGL2RenderingContext is defined in non-WebGL2 environments
+// so that apps can test their gl contexts with instanceof
+// E.g. if (gl instanceof WebGL2RenderingContext) { }
+class WebGL2RenderingContextNotSupported {}
+global.WebGL2RenderingContext = global.WebGL2RenderingContext || WebGL2RenderingContextNotSupported;
+
+// Ensure that Image is defined under Node.js
+class ImageNotSupported {}
+global.Image = global.Image || ImageNotSupported;
+
 export {global};
 export {lumaStats};
 export default global.luma;