normalize and vec4 oddness

Patches -> primitives

What is a patch?
	Up to 32 vertices
	

Tessellation Control Shader (TCS)
Tessellation Primitive Generator (not programmable)
Tessellation Evaluation Shader (TES)

TCS -> Primitive Generator -> TES

TCS outputs:
	Tessellation Level
	Vertices (can move stuff, like vertex and geometry shaders)
	Optional, can use glPatchParameterfv to set default values
		Transformation can be applied in the vertex shader instead

Primitive Generation:
	Normalized Coordinates (Barycentric coordinates)
		In triangles vs. in quads
		No awareness of "actual" coordinates!
	Tessellation levels:
		In general, these are the number of segments an edge is tessellated into
		Edge tessellation should match the neighboring patch
		Triangles:  One inner level, three outer levels	
		Can be discareded if level is 0
			That allows the TCS to cull patches
	Picture of how these come together

TES outputs:
	gl_Position
	Anything else we've defined, like color
	Calculate this from:
		gl_TessCoord (vec3, barycentric coordinates)
		gl_in with patch vertices
		
Demo:
	Add a tcs and tes to the cube to make it into a sphere
		using normalize
	Add shaders
	glPatchParameteri to set GL_PATCH_VERTICES
	draw GL_PATCHES
	The color pickle
	Using the geometry shader to draw lines instead of triangles
	
We now have only one type of shader remaining!

Practice problems:
	1.  Add a uniform to today's lab to control tessellation level in the TCS, and set up the CPU portion of the program to vary this over time.
	2.  Use the geometry shader to place the sphere inside a much larger duplicate sphere. 

Lab today:
	Adjust the TCS so that a detailed cube made up of little triangles is drawn.  Next, scale the locations like this:
	control_closeness = maximum influence of a single control point, taken from gl_TessCoord
	Instead of normalizing the lengths of the vectors to each point, scale them by control_closeness instead.