TIC-80

Fantasy computer for making, playing and sharing tiny games. · By Nesbox

Add to collection

tic80 Community Devlog

TIC-80 community

Key Press

A topic by NobodysSon created Jan 31, 2020 Views: 1,195 Replies: 9

Viewing posts 1 to 4

NobodysSon4 years ago

I'm having a problem with the last button that was pressed remaining active after it is released so that it triggers things later in my code.

Here is an example of what I mean.

--script: lua
state = "one"
function TIC()
    cls(0)
    
    if btn(4) then
        if state == "one" then
            state = "two"
        end
        
        if state == "two" then
            state = "three"
        end
        
        if state == "three" then
            state = "one"
        end
    end    
    
    if state == "one" then
        print("First state",0,0)
    end
    
    if state == "two" then
        print("Second state",0,0)
    end
    
    if state == "three" then
        print("Third state",0,0)
    end
    
end

I've wrestled with this for awhile trying both btn and btnp but I haven't gotten anywhere. Any help would be greatly appreciated!

Paul594 years ago (3 edits)

The problem is the if statements - if you press button 4 the state becomes 'two' but then you're immediately checking the state again . As the state is now 'two' it becomes 'three' and so on. So, in a single pass of TIC() your state goes 1->2->3->1 so it always prints as state one. The fix is to use 'else' clauses like this:

state = "one"
function TIC()
    cls(0)
    if btnp(4) then
        if state == "one" then
            state = "two"  
        elseif state == "two" then
            state = "three"      
        elseif state == "three" then
            state = "one"
        end
    end    
    
    if state == "one" then
        print("First state",0,0)
    elseif state == "two" then
        print("Second state",0,0)
    elseif state == "three" then
        print("Third state",0,0)
    end
end

I guess you'd also want to use btnp() as I've indicated otherwise the program will cycle through the states very quickly (try it, using trace() instead of print to see the state changing) - probably not what you want!

NobodysSon4 years ago

Thank you that solved my issues! I understand now what I was doing wrong.

TIC-80 seems a good environment for learning how to code.

Paul594 years ago(+1)

You could make the code much more compact like this, it depends whether you really want to show the state names in text:

state = 1
statenames={'One','Two','Three'}
function TIC()
    cls(0)   
    if btnp(4) then
        state=state+1
        if state==4 then state=1 end
    end
    print(statenames[state],0,0)     
end

State names might be 'menu', 'play', 'game over' or 'attack', 'flee', 'defend' etc :D