Implementing Quaternions

DAMN I finally got it working.

I parented one mesh to another and randomly spun the parent around on the screen. When I click the mouse, the child mesh gets parented to either the center mesh or the world. When I change the parenting, the mesh stays perfectly in place, no matter what crazy angle is happening. Here, see for yourself:
http://www.leadwerks.com/post/quat.zip

It will take some time to clean this up, but the hard part is done. I'm going to go drink now.

This extracts a quaternion from a matrix:

	Method ExtractQuat()
		fourWSquaredMinus1:Float = +grid[0,0]+grid[1,1]+grid[2,2]
		fourXSquaredMinus1:Float = +grid[0,0]-grid[1,1]-grid[2,2]
		fourYSquaredMinus1:Float = +grid[1,1]-grid[0,0]-grid[2,2]
		fourZSquaredMinus1:Float = +grid[2,2]-grid[0,0]-grid[1,1]

		biggestIndex=0
		fourBiggestSquaredMinus1:Float=fourWSquaredMinus1
		If fourXSquaredMinus1 > fourBiggestSquaredMinus1
			fourBiggestSquaredMinus1 = fourXSquaredMinus1 
			biggestIndex=1
		EndIf
		If fourYSquaredMinus1 > fourBiggestSquaredMinus1
			fourBiggestSquaredMinus1 = fourYSquaredMinus1 
			biggestIndex=2
		EndIf
		If fourZSquaredMinus1 > fourBiggestSquaredMinus1
			fourBiggestSquaredMinus1 = fourZSquaredMinus1 
			biggestIndex=3
		EndIf

		biggestValue:Float=Sqr(fourBiggestSquaredMinus1+1.0)*0.5
		mult:Float=0.25/biggestValue

		Select BiggestIndex
			Case 0
				w#=BiggestValue
				x#=(grid[1,2]-grid[2,1])*mult
				y#=-(grid[2,0]-grid[0,2])*mult
				z#=-(grid[0,1]-grid[1,0])*mult
			Case 1
				x#=-BiggestValue
				w#=-(grid[1,2]-grid[2,1])*mult
				y#=(grid[0,1]+grid(1,0))*mult
				z#=(grid[2,0]+grid[0,2])*mult
			Case 2
				y#=BiggestValue
				w#=-(grid[2,0]-grid[0,2])*mult
				x#=-(grid[0,1]+grid(1,0))*mult
				z#=(grid[1,2]+grid[2,1])*mult
			Case 3
				z#=-BiggestValue
				w#=(grid[0,1]-grid(1,0))*mult
				x#=(grid[2,0]+grid[0,2])*mult
				y#=-(grid[1,2]+grid[2,1])*mult
		EndSelect

		If w<-0.0
			x=-x
			y=-y
			z=-z
			w=-w
		EndIf

		VECTOR_X=z
		VECTOR_Y=x
		VECTOR_Z=y
		VECTOR_W=w		
	EndMethod