Merge branch 'master' of github.com:gl-modules/shader-school

Author: hughsk

README.md

@@ -9,9 +9,9 @@
 ## Running this thing
 
 First, you need to [get a browser with WebGL](http://get.webgl.org/), as well
-as a copy of [node.js](http://nodejs.org/). Once you have all of that set up,
-you can install the workshop using [npm](http://npmjs.org/), which is included
-with node:
+as a copy of [node.js](http://nodejs.org/) and [git](http://git-scm.com/). Once you have
+all of that set up, you can install the workshop using [npm](http://npmjs.org/), which
+is included with node:
 
 ```
 npm install -g shader-school

exercises/02-intro-2/README.md

@@ -65,7 +65,7 @@ void test() {
   testFunction(x, y, z, w);
 
   //Now:
-  //  x == 2.0
+  //  x == 1.0
   //  y == 3.0
   //  z == 4.0
   //  w == -1.0

exercises/03-intro-3/README.md

@@ -6,6 +6,27 @@ In this lesson, you will write a GLSL function which computes the unit angle bis
 
 As an example, if `a = vec2(1,0)` and `b = vec2(0,1)`, then you should return the result `vec2(sqrt(2)/2, sqrt(2)/2)`.
 
+**Hint** It is useful to remember the angle bisector theorem.  In ascii art, suppose we have two vectors, A and B.  Then the angle bisector between A and B is the vector C:
+
+```
+ B
+ ^
+ |\
+ | \^ C
+ | /\
+ |/  \
+ *----> A
+ O
+```
+
+In this situation, the angle bisector theorem tells us the following information about the ratio of the lengths of these vectors:
+
+```glsl
+length(B - C) / length(C - A) == length(B) / length(A)
+```
+
+Using the above equation, solve for the position of C and then normalize it to unit length.
+
 ***
 
 After scalars, the next most important data type in GLSL are vectors.  GLSL comes with built in types for small vectors with up to 4 components.  Like scalars, vectors come in boolean, integer and floating point varieties which are declared using the following syntax:

exercises/05-intro-5/README.md

@@ -23,11 +23,11 @@ vec2 z2 = mandelbrot(z1, c);    // 2 iterations
 vec2 zn = mandelbrot(zn_1, c);  // n iterations
 ```
 
-As a general principle, say that a point in the Mandelbrot set diverges if it has a magnitude greater than 2:
+As a general principle, say that a point in the Mandelbrot set diverges if it has a magnitude greater than 2, so we will classify points as inside the set if their magnitude is less than 2:
 
 ```glsl
-bool mandelbrotDiverges(vec2 z) {
-  return length(z) >= 2.0;
+bool mandelbrotConverges(vec2 z) {
+  return length(z) < 2.0;
 }
 ```
 

package.json

@@ -1,7 +1,7 @@
 {
   "name": "shader-school",
   "version": "0.0.0",
-  "description": "",
+  "description": "Self directed GLSL lessons",
   "main": "index.js",
   "bin": "index.js",
   "scripts": {