Lab 02: Xiaonan Pan

README.md

@@ -1,5 +1,24 @@
 # lab02-debugging
 
+# Xiaonan Pan's Submission
+
+Henry Han assisted me with the puzzles.
+[Shadertoy Solution](https://www.shadertoy.com/view/tcsfWf)
+
+## Bug List
+
+1. The variable name `uv2`
+
+   - The error info from shadertoy directly guides to its location
+2. The width - height ratio, change `H` to `H *= len * iResolution.x / iResolution.y`; 
+   - After the fix of bug 1., I notice the screen is kind of stretched, from my experience, this may relate  to the camera set and  screen resolution. As this project is raycast based, raycast is somehow the camera, so I go through its code first and find the problem
+3. Replace `reflect(eye, nor)` by `reflect(dir, nor)`
+   - Incorrect shading could come from incorrect hit info(like hitObjectID, shading model. material parameters) given by Intersection. I went to the Intersection and saw that the shading model is quite simple, just returning the color where the ray reflected to.  So, the missing reflection effects could be from the `reflect()` function as it goes to incorrect position to get color.
+4. Increase the max iteration number of `march()`, and use `nor` instead of `dir` to offset the intersection to avoid the false negative hit near the object 
+   -  The overall shapes looks smooth with a solid heigh-width ratio, so, the major of the code should be correct.
+   - I just played with the parameters to see if any artifacts disappear.
+
+
 # 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).