electronic_steve's script from http://tpt.io/.272754

local screen = {}
screen.width = 600
screen.height = 300
nodeList = {}
nodeRadius = 2
numNodes = 50
dt=0.03
for i=1, numNodes do
    local node = {}
    node.x = math.random(screen.width)
    node.y = math.random(screen.height)
    local v = math.random(200)
    local th = math.random(2*math.pi)
    node.vx = v*math.cos(th)
    node.vy = v*math.sin(th)
    nodeList[i] = node
end
phyClock = {}
phyClock.curTime = 0
springConstant = 75
maxDist = 120
curTime = 0

function newprintpixel(x,y,r,g,b)
    if x>0 and x0 and y< 184 then
        tpt.drawpixel( x,y)
    end
end

function update()
    curTime = curTime + dt
    while phyClock.curTime < dt do
        phyClock.curTime = phyClock.curTime + 0.01
        for i=1, numNodes do
            local A = nodeList[i]
            for j=i+1, numNodes do
                local B = nodeList[j]
                local dx = (A.x-B.x)
                local dy = (A.y-B.y)
                local dist = dx^2 + dy^2
                if dist < maxDist*maxDist then
                    local ang = math.atan2(dy, dx)
                    local falloff = 1-dist/(maxDist*maxDist)
                    local F = springConstant*falloff
                    A.vx = A.vx - F*math.cos(ang)*0.01
                    A.vy = A.vy - F*math.sin(ang)*0.01
                    B.vx = B.vx + F*math.cos(ang)*0.01
                    B.vy = B.vy + F*math.sin(ang)*0.01
                end
            end
        end
        for i=1, numNodes do
            local node = nodeList[i]
            node.x = node.x + node.vx*0.01
            node.y = node.y + node.vy*0.01
            if node.x+nodeRadius < 0 then
                node.x = screen.width + nodeRadius
            elseif node.x-nodeRadius > screen.width then
                node.x = -nodeRadius
            end
            if node.y+nodeRadius < 0 then
                node.y = screen.height + nodeRadius
            elseif node.y-nodeRadius > screen.height then
                node.y = -nodeRadius
            end
        end
    end
    phyClock.curTime = phyClock.curTime - dt
end

function HSL(h, s, l, a)
    if s<=0 then
        return l,l,l,a
    end
    h, s, l = h/256*6, s/255, l/255
    local c = (1-math.abs(2*l-1))*s
    local x = (1-math.abs(h%2-1))*c
    local m,r,g,b = (l-.5*c), 0,0,0
    if h < 1 then
        r,g,b = c,x,0
    elseif h < 2 then
        r,g,b = x,c,0
    elseif h < 3 then
        r,g,b = 0,c,x
    elseif h < 4 then
        r,g,b = 0,x,c
    elseif h < 5 then
        r,g,b = x,0,c
    else
        r,g,b = c,0,x
    end
    return (r+m)*255,(g+m)*255,(b+m)*255,a
end

function draw()
    for i=1, numNodes do
        local node = nodeList[i]
        newprintpixel( node.x, node.y,0, 255, 255)
        for j=i+1, numNodes do
            local b = nodeList[j]
            local dist = (node.x-b.x)^2 + (node.y-b.y)^2
            local falloff = math.max((1-dist/(maxDist*maxDist)), 0)
            if falloff > 0 then
                tpt.drawline(node.x, node.y, b.x, b.y,HSL((falloff*255+curTime*32)%255, 255, 128, falloff*255))
            end
        end
    end
end

tpt.register_step(update)
tpt.register_step(draw)