Visualization of 2d Lambertian reflection vectors

...as described in Peter Shirley's Ray Tracing in One Weekend

Cameron Christensen - Fall 2021

Lambertian almost	Lambertian proper

Algorithms

• One method, called "almost Lambertians," creates vectors from random points in a unit circle. This is the default so you'll be more impressed when you see the other method.
• Another method projects these random points to the edge of the circle and creates vectors from these. You can see the distribution of vectors is more even across the hemisphere.
• Finally, the hemisphere was added, but its weaknesses are unclear, especially here in 2d.

Shortcuts

'l'/'L' to cycle between methods
'c' to toggle source
'r' refresh
'+'/'-' inc/dec lines
'a' artistic colors
'g' toggle gui

Stuff

Maybe somebody has done this already, and likely better. It's probably the first comment I'll get on it.

I just wanted to better understand and compare these algorithms for Lambertian reflection.
This is my first use of jquery, svg, etc, and super hacky at that.

I just wrote quick Vec and Ray classes because I was too lazy to cut and paste anything, much less find a module to import, then learn how to use it--I just wanted to see some lines, remember? Plus xxXxXx has traumitized me so much that I now avoid ever wanting to use anyone else's libraries ever again.

Yes, I'm going to share this, and I don't want to be judged on this crap code, but it's still cool to press a couple keys to see the differences between these methods more clearly illustrated.

WARNING: ...and for hack sakes, don't look at this and try to actually create a reflection vector in real life.

TODO

More like "other things I'm curious to examine offline." By "offline" I mean outside the place where they'll be used, e.g., a ray tracer.

• other kinds of reflections, like smoother operators and psychiatric
• use random theta with hemi-circle to emulate uniform selection of theta on hemisphere
• 3d
• refractions