Lab 2: Gehan Zheng

README.md

@@ -1,5 +1,24 @@
 # lab06-debugging
 
+# Team members
+
+No team members.
+
+# Shader Toy Links
+
+[Fork 566 Debugg gehanzh 366](https://www.shadertoy.com/view/cs3yR2)
+
+# Bugs
+
+1. At first it just doesn't compile. So I found that it should be `vec2` instead of `vec` in line 97.
+
+2. Transformation looks wrong. So I look into `raycast` function and found that in line 11 there's a typo `iResolution.x / iResolution.y` instead of `iResolution.x / iResolution.x`.
+
+3. Transformation is still wrong but there is nothing wrong in `raycast` function. So I found that `raycast` is called with wrong parameters in line 100. The first parameter should be `uv2` instead of `uv`.
+4. The material doesn't look specular. And I noticed that eye vector is passed to `reflect` function, which is definitely wrong. Change it to `dir` and it looks the same as the reference.
+5. Reflection doesn't look the same as the reference. It is because number of iterations is too small. 
+
+6. (Not sure if it's a bug) It looks like Schlick's approximation is used to compute fresnel but `pow` is missing, so I fixed and it looks more specular now.
 # Setup 
 
 Create a [Shadertoy account](https://www.shadertoy.com/). Either fork this shadertoy, or create a new shadertoy and copy the code from the [Debugging Puzzle](https://www.shadertoy.com/view/flGfRc).