bring back comment

examples/webgl_materials_extended_instancing.html

@@ -54,10 +54,74 @@
 
 
 	<script>
-
 		/*eslint-disable*/
 		if ( ! Detector.webgl ) Detector.addGetWebGLMessage();
 
+		/**
+		 * Requirement:
+		 * 
+		 *   Render the same geometry multiple times with varying scale and position.
+		 *
+		 * Problem:
+		 *
+		 *   Rendering a scene graph with multiple Mesh objects sharing the same geometry
+		 *   causes many draw calls to happen, incurring overhead.
+		 *
+		 * Solution:
+		 *
+		 *   Use instancing with InstancedBufferGeometry to draw multiple instances within
+		 *   one draw call.
+		 *
+		 * Pitfall:
+		 *
+		 *   Instancing requires GLSL code not present in built-in materials in order to work.
+		 *
+		 * Solution:
+		 *
+		 *   Couple additional GLSL code with materials, and inject it at parse time into the built-in materials.
+		 *   
+		 */
+
+
+		/**
+		 * All the built in materials are based on shader templates that can be found here:
+		 * https://github.com/mrdoob/three.js/tree/dev/src/renderers/shaders/ShaderLib
+		 *
+		 * Each Material consists of a vertex and fragment shader which are suffixed with _vert and _frag.
+		 *
+		 * These templates consist of a list of #include statements which point to various GLSL chunks that
+		 * can be found here:
+		 * https://github.com/mrdoob/three.js/tree/dev/src/renderers/shaders/ShaderChunk
+		 *
+		 * Some of the functionality overlaps, for example the MeshStandardMaterial is much more complex than
+		 * MeshBasicMaterial, but both need to perform the same discrete steps for basic 3d transformations.
+		 * 
+		 */
+
+
+		/**
+		 * We want to perform instancing in lieu of setting Mesh.position.
+		 * A chunk present in most of the vertex shaders is:
+		 * https://github.com/mrdoob/three.js/blob/dev/src/renderers/shaders/ShaderChunk/begin_vertex.glsl
+		 *
+		 * This is one line of GLSL code:
+		 *
+		 * vec3 transformed = vec3( position );
+		 *
+		 * It declares a vec3 variable called "transformed" and copies the value from the position buffer.
+		 * After this chunk executes, "transformed" holds the value from Geometry.vertices, this is referred to
+		 * as "model space".
+		 *
+		 * The next stage of the transformation uses the "modelViewMatrix" to transform the vertex into view space.
+		 * https://github.com/mrdoob/three.js/blob/dev/src/renderers/shaders/ShaderChunk/project_vertex.glsl
+		 *
+		 * The modelViewMatrix is derived from the data we set with Mesh.position. We can insert another level
+		 * of transformation in between this. The Mesh doing the instancing assumes the role of a Group, and a 
+		 * buffer on InstancedBufferGeometry assumes the role of many Mesh objects that are a child of that Group.
+		 * 
+		 */
+
+
 		//we will need some kind of input to the shader
 		//this example will set a uniform scale and a position offset
 		var global_instance_chunk =