A question about timing in Pico 8

Sun, 06 Aug 2023 21:38:11 UTC

Heyo people!

So, I'm having some trouble getting my head around the timing of everything when it comes to Pico 8, Lua, and I guess programming in general. Something that troubles me is how for loops act when running a game.

Right now, I have a piece of code that displays several circles along a straight line, one circle being created for each pixel of distance between the player sprite and a mouse click location. Here is the code:

if band(mousebtn,1) > 0 then
 ropes={}
    mouseclick=true
end

if mouseclick==true then

    --get last mouse coords
    local lcursx=mousex
    local lcursy=mousey 
    --get last player coords
    local lpx=p.x+8
    local lpy=p.y

    local dist, angle = gettraj(lcursx,lcursy)

    for i=1,flr(dist) do
        local dirx=lpx+cos(angle)*i
        local diry=lpy+sin(angle)*i

        add(ropes, {x=dirx,y=diry})
    end

    mouseclick=false
end

Now, I've been messing around with this for loop for about 3 hours, trying to figure out how to create these 'rope' particles sequentially, one by one, over a specific span of time.

I've tried wrapping it in a timer...

t=time() -- upon button click get time

        for i=1,flr(dist) do
                if time()-t>1 then
                local dirx=lpx+cos(angle)*i
                local diry=lpy+sin(angle)*i

                add(ropes, {x=dirx,y=diry})
                        t=time()
                end
    end

I've also tried wrapping the timer around the add(ropes)... statement alone, doing all sorts of timey wimey stuff that I'm seeing in tutorials and in the forums, and nothing has worked. I wish I could post all of the iterations of failure but that would be very boring.

I've also considered creating each rope particle, and then having them move incrementally towards the mouse location, before freezing the entire table of particles in place. Perhaps that would give me greater control over the 'extending rope' effect.

So, I guess I'm just wondering, how does the for loop really work? Does placing a timer within the loop mean that one second should be passing each time the loop runs? Does the loop finish its full duration before continuing with any code below? And also, if you have any suggestions on how to get these little ropey fellas to spawn based on a timed sequence, please let me know.

-- I feel like I'll be posting a lot here since I'm just starting, apologies if my questions begin to grate.

Trajectory help?

Sun, 06 Aug 2023 02:20:54 UTC

Heyo people! I've been learning Pico 8 for a few weeks now, created a few little test games to learn the language, now I'm trying to start a game I intend to finish and polish - thought it might be useful to start interacting on the boards. I'm having some issues with the mathematics of this game I'm making.

Playing as a small turtle with a cactus on it's back, the main mode of interaction will be snatching other entities out of the air with rope-like tendrils that come from within the cactus. However, right now, I'm having a lot of difficulty trying to figure out why my tendrils are not lining up to the angle of the mouse's location (using mouse input). Sine, cosine, pi, all that stuff terrifies me, so if someone out there wouldn't mind taking a gander at the small amount of code I've written for this project so far, I'd appreciate any advice!

Thanks!

The I suspect the problem lies somewhere here...

function gettraj(mx,my)
    --get x/y distances
    local hdist=p.x-(mx+4)
    local   vdist=p.y-(my+4)

    --get diagonal distance
    local dist=sqrt(hdist^2+vdist^2)

    --get angle to cursor in degrees
    local angle=(atan2(vdist,hdist)*180/pi)+45

    return dist, angle
end

function update_game()
    mousex=stat(32)
    mousey=stat(33)

    mousebtn=stat(34)

    if band(mousebtn,1) > 0 then
        --get last mouse coords
        local lcursx=mousex
        local lcursy=mousey 
        --get last player coords
        local lpx=p.x+8
        local lpy=p.y

        local dist, angle = gettraj(lcursx,lcursy)

        for i=1,flr(dist) do
            local dirx=lpx+cos(angle*pi/180)*i
            local diry=lpy-sin(angle*pi/180)*i

            add(ropes, {x=dirx,y=diry})
        end

    end
end

turtgame

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A question about timing in Pico 8

Trajectory help?