edit docs

Author: peteroupc

objmtl.js

@@ -23,7 +23,11 @@ function MtlData(){
 }
 /**
  * Creates one or more 3D shapes from the data
- * in this OBJ file.
+ * in this OBJ file.<p>
+ * To use this class, you must include the script "objmtl.js"; the
+ * class is not included in the "glutil_min.js" file which makes up
+ * the HTML 3D Library.  Example:<pre>
+ * &lt;script type="text/javascript" src="glutil_min.js">&lt;/script></pre>
  * @param {Scene3D} scene 3D scene to load the shape with.
  * @return {glutil.ShapeGroup} Group of shapes.
  */

stl.js

@@ -6,20 +6,26 @@ http://creativecommons.org/publicdomain/zero/1.0/
 If you like this, you should donate to Peter O.
 at: http://upokecenter.dreamhosters.com/articles/donate-now-2/
 */
+
+if(!GLUtil){
+ GLUtil={};
+}
+(function(GLUtil){
+var StlData={};
 /**
-Loads a .STL file asynchronously.
+* Loads a .STL file asynchronously. 
+* To use this class, you must include the script "stl.js"; the
+ * class is not included in the "glutil_min.js" file which makes up
+ * the HTML 3D Library.  Example:<pre>
+ * &lt;script type="text/javascript" src="stl.js">&lt;/script></pre>
+@alias glutil.GLUtil.loadStlFromUrl
 @param {string} url The URL to load.
 @return {Promise} A promise that:
 - Resolves when:
 The .STL file is loaded successfully.  The result is a Mesh object.
 - Is rejected when:
 An error occurs when loading the .STL file.
 */
-if(!GLUtil){
- GLUtil={};
-}
-(function(GLUtil){
-var StlData={};
 GLUtil.loadStlFromUrl=function(url){
  return GLUtil.loadFileFromUrl(url).then(
    function(e){

tutorials/camera.md

@@ -0,0 +1,22 @@
+## The "Camera" and the Projection and View Transforms
+
+The `Scene3D` class has a concept of a "projection transform" and a "view transform". If we use the concept of a "camera", the projection is like setting the camera's focus and lens, and the view transform is like setting its position and orientation. `Scene3D` has methods for setting all these attributes of this abstract "camera". Two of them are `setPerspective()` and `setLookAt(), which are shown in the example below.
+
+  // Set the perspective view.  Camera has a 45-degree field of view
+  // and will see objects from 0.1 to 100 units away.
+  scene.setPerspective(45,scene.getAspect(),0.1,100);
+  // Move the camera back 40 units.
+  scene.setLookAt([0,0,40]);
+  // Move the camera back 30 units instead, and turn it so it
+  // points at (0, 2, 0), that is, up 2 units.
+  scene.setLookAt([0,0,30], [0,2,0]);
+
+In 3D graphics, the two most commonly used projections are the perspective projection and the orthographic projection.  Both are described in detail below.
+
+### Perspective Projection
+
+A perspective projection gives the 3D scene a sense of depth.  In this projection, closer objects look bigger than more distant objects with the same size.  The `Scene3D` class's `setPerspective()` method defines a perspective projection.
+
+### Orthographic Projection
+
+In an orthographic projection, objects with the same size don't vary in size with their depth.  The `Scene3D` class's `setOrtho()` and `setOrthoAspect()` methods define an orthographic projection.