https://paroj.github.io/gltut/Illumination/Tutorial%2009.html
	This is pretty old, but still relevant

Special for today:
	http://www.lighthouse3d.com/tutorials/glsl-12-tutorial/the-normal-matrix/

Notes about progress of the course:
	I'm heading toward ray tracing
	Already finished the intro class and example, actually
		Adding some stuff to the nVidia tutorials
	Still thinking about the best amount of abstraction
		Concerned nVidia is too much still
		Haven't got it to build on FreeBSD yet
		Maybe it's actually easy on Windows?  Would somebody mind checking?
		I can, but it'll take me forever

Normals, and calculation in differenct spaces
	The model is not actually in model space if we've scaled, etc.
	The normal vectors are in model space
	MVP and what happens to these
		Short answer:  Compute the inverse-transpose matrix, and multiply by that instead
		Make sure it's 3x3 to kill translation.  Could also just set w to 0.
		If you're really interested in 3D, take linear algebra.  It counts as an upper-division elective
		Do it once on the CPU instead of a whole bunch of times on the card
	This is only a problem if the object has had a non-uniform scale applied
		Can avoid overhead if you just make the models so they don't need a non-uniform scale

Alright:  Goal I haven't gotten to for a long time
	I'd like a point source lab
	Let's improve the load_object a little for this
		I already did, at least party
		To save you watching too much of me typing
	
Point lighting:
	A directional light for diffuse lighting comes from some direction
	A point light comes from a point
	We can figure out a direction to a point, not a problem?
		Fragment shader:  Must preserve surface location and normal
	Attenuation:
		Decrease light power with distance!
		Real:  I / (1.0 + k*r^2)
		k constant:  Can use distance where half the light is lost
		Less attenuation:  I / (1.0 + k*r)
			Just take out the r, and lights work when further away
		Calculations happen in world-space distances
			Can compute from camera space, or preserve, or whatnot

Specular Reflection:
	Reflection in a specific direction!
		Comes with a different color
		Microfacets, roughness
		Angle to the camera matters!
		Phong:  dot product of V and R raised to the s power
		V is the viewing direction
		R is the reflection direction
		s is a term that represents roughness
		The Phong term is multiplied by the light intensity and the specular absorption
			Specular absorption might not be the same color as diffuse absorption
			Only works for angle less than 90
		Blinn term:  Use half angle vector
		Gaussian:  Probability distribution of microfaucets