lua script to show a very basic tutorial in The Powder Toy

tutorial.lua

function lerp(a,b,t)
    return {(a[1]*(1-t))+(b[1]*t),(a[2]*(1-t))+(b[2]*t)}
end

function bezier(p0,p1,p2,p3,t)
    local p4=lerp(p0,p1,t)
    local p5=lerp(p2,p3,t)
    local p6=lerp(p4,p5,t)
    return p6
end

function drawbezier(p0,p1,p2,p3,r,g,b)
    if r==nil then
        r=255
        g=255
        b=255
    end
    local pp2=nil
    local pp1
    for i=0,10 do
        t1=i/10
        pp1=bezier(p0,p1,p2,p3,t1)
        --p2=bezier(p0,p1,p2,p3,t2)
        if pp2 then
            graphics.drawLine(pp1[1],pp1[2],pp2[1],pp2[2],r,g,b)
        end
        pp2=pp1
    end
end

function drawarrow(s,e,dir,r,g,b)
    if r==nil then
        r=255
        g=255
        b=255
    end
    local dir=math.rad(dir)
    local ln=128
    local dp={e[1]+math.cos(dir)*ln,e[2]+math.sin(dir)*ln}
    drawbezier(s,dp,dp,e,r,g,b)
    
    graphics.drawLine(e[1],e[2],e[1]+math.cos(dir+math.pi*0.15)*16,e[2]+math.sin(dir+math.pi*0.15)*16,r,g,b)
    graphics.drawLine(e[1],e[2],e[1]+math.cos(dir-math.pi*0.15)*16,e[2]+math.sin(dir-math.pi*0.15)*16,r,g,b)
end

function drawoutlinearrow(s,e,dir)
    for x=-2,2 do
        for y=-2,2 do
            drawarrow({s[1]+x,s[2]+y},{e[1]+x,e[2]+y},dir,0,0,0)
        end
    end
    
    drawarrow(s,e,dir)
end

function drawoutlinebezier(p0,p1,p2,p3)
    for x=-2,2 do
        for y=-2,2 do
            drawbezier({p0[1]+x,p0[2]+y},{p1[1]+x,p1[2]+y},{p2[1]+x,p2[2]+y},{p3[1]+x,p3[2]+y},0,0,0)
        end
    end
    drawbezier(p0,p1,p2,p3,255,255,255)
end

function drawfreearrow(p0,p1,p2,p3,r,g,b)
   if r==nil then
        r=255
        g=255
        b=255
    end
    drawbezier(p0,p1,p2,p3,r,g,b)
    
    local sp=bezier(p0,p1,p2,p3,0.9)
    local ep=bezier(p0,p1,p2,p3,1)
    
    local dir=math.atan2(sp[2]-ep[2],sp[1]-ep[1])
    graphics.drawLine(ep[1],ep[2],ep[1]+math.cos(dir+math.pi*0.15)*16,ep[2]+math.sin(dir+math.pi*0.15)*16,r,g,b)
    graphics.drawLine(ep[1],ep[2],ep[1]+math.cos(dir-math.pi*0.15)*16,ep[2]+math.sin(dir-math.pi*0.15)*16,r,g,b)
end

function drawoutlinetext(textpos,text)
    for x=-2,2 do
        for y=-2,2 do
            graphics.drawText(textpos[1]+x,textpos[2]+y,text,0,0,0)
        end
    end
    
    graphics.drawText(textpos[1],textpos[2],text)
end

function drawinstruction(text,point,dir)
    textwidth=graphics.textSize(text)
    arrowpos=lerp({314,212},point,0.5)
    textpos={arrowpos[1]-textwidth/2,arrowpos[2]-5}
    
    drawoutlinearrow(arrowpos,point,dir)
    
    drawoutlinetext(textpos,text)
    
end

function hide_all()
    for k,v in pairs(tpt.el) do tpt.el[k].enabled = 1 tpt.el[k].menu=0 end
end

function show_all()
    for k,v in pairs(tpt.el) do tpt.el[k].enabled = 1 tpt.el[k].menu=1 end
end

function init()
    tpt.register_mouseclick(function(mx,my,btn,ev)
        
    end)
end

function lvl01_fire()
    sim.loadSave(1558068,1)
    hide_all()
    tpt.el.plnt.enabled=1
    tpt.el.plnt.menu=1
    local hadplant=false
    stepfunction=function()
        if sim.elementCount(tpt.element("firw"))==0 then
            drawoutlinetext({314,212},"A winner is you!")
        else
            if sim.elementCount(tpt.element("plnt"))>1000 or hadplant then
                --500,218
                drawinstruction("burn",{500,218},270)
                hadplant=true
            else
                if tpt.selectedl=="DEFAULT_PT_PLNT" then
                    tpt.brushx=32
                    tpt.brushy=32
                    drawoutlinetext({314,212},"draw")
                    drawfreearrow({50,280},{50,0},{550,400},{550,280})
                else
                    if tpt.active_menu()~=9 then
                        drawinstruction("select the 'solids' menu",{610,302},180)
                    else
                        drawinstruction("select the 'PLNT' element",{588,370},270)
                    end
                end
            end
        end
    end
    
end

stepfunction=nil

do
    local modal=Window:new(16,171,596,80)
    interface.showWindow(modal)
    
    local b=tpt.el.dust.color%256
    local g=bit.rshift(tpt.el.dust.color,8)%256
    local r=bit.rshift(tpt.el.dust.color,16)%256
    local freeplaybutton=Button:new(4,4,96,32,"\15"..string.char(r,g,b)..string.char(208).." Free Play")
    modal:addComponent(freeplaybutton)
    freeplaybutton:action(function(sender) interface.closeWindow(modal) end)
    
    local freeplaytext=Label:new(52,4,540,32,"All elements are available from the start.")
    modal:addComponent(freeplaytext)
    
    local careerbutton=Button:new(4,44,96,32,"\15"..string.char(1,255,1)..string.char(207).." Career mode")
    modal:addComponent(careerbutton)
    careerbutton:action(function(sender) interface.closeWindow(modal) init() lvl01_fire() end)
    
    local careertext=Label:new(52,44,540,32,"Unlock elements as you discover them. reccomended for new players")
    modal:addComponent(careertext)
    
    tpt.register_step(function()
        if stepfunction~=nil then
            stepfunction()
        end
        end)
end