CircleCollision_01

    ----------------------------------------------------------------------------------------
    --  Circle Collision
    --
    --  Dynamic Circle packing
    --  Circles are placed in a domain and then push their neighbors till there are no overlaps
    --
    --  Michael Spaw
    --  Morphographic.com
    --  Started 02/05/13
    --  ver 0.01 02/08/13
    --
    --  Here are the steps for the algorithm
    --  1. N# of circles are placed randomly within the bounding shape
    --    and the wirecolor is set to yellow
    --  2. For each circle its closest neighbor is found
    --  3. Based on the vector between the circle and its closest neighbor the circle
    --      is moved just a bit in the oposite dirrection
    --  4. The  neighbor and repulsion setp is looped through till there are no overlaps
    --
    --  Also of note you can see the wirecole change based on if the circle has been moved or is stationary
    ----------------------------------------------------------------------------------------

    -- Setup
    aqua = (color 87 224 198)--Create a color to be used for the bounding shape
    drawRad = 3 --the radius of the circles
    radvary = 0.7 --The amount of variation in the radius of the circles
    numcircles =200 --Total number of circles created within the test
    Iterations = 5000 --Total attemps to move the cicrcles so they no longer collide

    initxpos = 50.0-drawrad --Inital x position for the circle minus some to keep it in the bounding rectangle
    initypos = 50.0-drawrad --same for the y

    delete objects--Lets clearout all the objects before we start

    Rectangle length:100 width:100 pos:[0,0,0] wirecolor:aqua  --a nice bounding rectangle for neatness

    fn blendcolor a b x =
    (
        return ((a) * (1 - (x)) + (b) * (x))
    )

    blendTime = 10
    startColor = red
    endColor = yellow

    fn setColor startColor endColor obj blendTime = (
            StartColorV = [startColor.r,startColor.g,startColor.b]
            endColorV = [endColor.r,endColor.g,endColor.b]
            colorDelta = (StartColorV - endColorV)*(1.0/blendTime) *-1
            currentColor = [obj.wirecolor.r,obj.wirecolor.g,obj.wirecolor.b]
            L = (length (endColorV - currentColor))
            if (L > (length colorDelta)) then (
                newColor = currentColor + colorDelta
                obj.wirecolor = (color newColor.x newColor.y newColor.z)
            )
                else
            (
                obj.wirecolor = endColor
            )
    )

    --Make some circles in the bounding area
    Circles= #()
    for i = 1 to numcircles do
    (
        p = (random [-initxpos,-initypos ,0.0] [initxpos,initypos,0.0])
        randRad = drawRad + (random (drawRad*-radvary) (drawRad*radvary))
        myCircle = circle pos:p radius:randRad wirecolor:startColor
         append circles myCircle
    )

    circlescolor= #()
    for i = 1 to numcircles do
    (
        circleColorVal = 0.0
        append circlescolor circleColorVal
    )

    fn findClosestNodes circles obj =
    (
        closestNodes = #()
        for i=1 to circles.count do ( -- loop through the circles to find any that are within the radius of the circle in question (obj)
            if obj!=circles[i] do ( --check to make sure we aren't comparing against ourself
                (
                    currDist = distance obj.pos circles[i].pos -- get the dist between comparison pairs
                    if (currDist < (obj.radius+circles[i].radius)) do ( -- if the circles overlap, add to the return array
                        append closestNodes circles[i]
                    )
                )
            )
        )
        return closestNodes
    )

    --Time for some collision testing and movement
    for j=1 to iterations do (
        noChange = true
        for i = 1 to circles.count do (
            closestCircles =  findClosestNodes circles circles[i]
            if closestCircles.count == 0 do (setColor startColor endColor circles[i] blendTime)
            for k=1 to closestCircles.count do (
                ra = circles[i].radius
                rb = closestCircles[k].radius
                rad = ra+rb
                d = distance closestCircles[k].pos circles[i].pos
                if (d < rad) do (
                    noChange = false
                    currentpos = circles[i].pos
                    v = (closestCircles[k].pos - circles[i].pos) * -0.05
                    circles[i].pos += v
                    newpos = circles[i].pos
                    if (newPos != currentpos) do (circles[i].wirecolor = red)
                )
            )
        )
        if noChange do (
            circles.wirecolor = yellow
            format "Number of iterations: %\n" j
            exit
        )
        forceCompleteRedraw()
        windows.processPostedMessages()
    )