/* Program goals:

	2.22.2003 -in btown
	-Emulate 2D particle-field interactions
	-Upgradeable to 3D

	Adjustments and effects:
		-numParts: performance IP to square
		-timeStep: time used to calc displacement of each frame,
				time for each frame
		-frameStep: Actual pause (ms) btewn frames
		-forceFactor: larger means more inertia
		-forcePower: exponent of distance
		> working on tracker algorithm
			-Slight offset in offsets is divergent from 
			-The acceleration of the collective particles 
			 overcomes the adjustment algorithm - the 
			 offsets arnen't adding fast enough to keep up
			 with the body.
			-Reexamine follower algorithm
			-make adjustment for some average velocity, like have 
			 a coefficient that is DP to velocity.
			-simplified algorithm
		> Optimized conditionals in update(g)
		PROB: ?
			- Eventually particles are divergent
			- energy of system increases due to invalid FORCE(dist) function
			- use units, convert px to meters or Km and just use science instead
			  of minor adjustment tweaks.
		> adjusting tracker to follow system center of mass
		LATER: centerX = sum(m1*x1 m2*x2 ...)/sum(m1 m2 ...)

	2.28.2003 -
		Adding text input for forcePower variable.		
	3.13.2003 -
		-Focus window by zooming out, instead of following one particle.
		- the goal: keep all particles on the screen
			- Calculate furthest distance between max and min x and y values
			- Must also center w/ an offset.. 
				- use offset of minx + (maxx-minx)/2
					and     miny + (maxy-miny)/2
					- the logic?
						-the minimum x or y value should be at or near the minimum point
						 of the screen.
					- test:
						- if minx = 0 and maxx = 500, then 
						  offset = 0 + 500/2 = 250.  // SHOULD BE 0.
					- iterate:
						- so maybe xoff = minx + (maxx-minx)/2 - MAXX/2;
					- test:
						minx=-500, maxx=0;
						xoff = -500 + (500)/2 - 250 = -500; NO. minx+xoff should = 0;
				-screen should center on the point (maxx-minx)/2, (maxy-miny)/2.
				given a point (x, y), how to center there?
					-offset the point being drawn by the difference between that point and 
					 the center point?
				given a range of occupied space, how to zoom to fit screen?
					- multiply all positions by a factor.. no, that is
					  dependent on the quadrant.

		Taking out current follower code.
		-increased part mass, sped up timestep GOAL: stabalize
		- reduced forcePower to .5
		- reduced forceFactor too.  more stable, clumpy now