Touch Zoom

Questions
1

Hello,

I want to zoom an image with two fingers. My problem is that I can not find the x, y of each touch separately, touch 1 and touch 2.

Can anyone tell me how to do this?

2

Hi @Georgian, check out the Multitouch example, it captures all the touches in a table, rather than using CurrentTouch.

3

I tried, but not working for me. Maybe an example would be helpful. No, maybe two examples: first example about coordinates x, y and second example about Touch Zoom using two fingers. If you help me, I’m very grateful for your help. :slight_smile: Some things seem a little strange such as Multitouch.

4

Not sure this is my best code, but it should get y started. Working “Pinch to zoom” here.

function setup()
    s = 0
    touches = {}
    dist = 0
    tcount = 0
end

function draw()
    background(40, 40, 50)
    pushMatrix()
    translate(WIDTH/2 * s * -1, HEIGHT/2 * s * -1)
    scale(s+1,s+1)
    sprite("Planet Cute:Star",WIDTH/2, HEIGHT/2)
    popMatrix()
end

function touched(touch)
    if touch.state == ENDED then
        touches[touch.id] = nil
        tcount = tcount - 1
    elseif touch.state == MOVING then
        touches[touch.id] = touch
        if tcount == 2 then
            local ct = 1
            for i,t in pairs(touches) do
                if ct == 1 then
                    firstpt = vec2(t.x,t.y)
                    ct = ct + 1
                else
                    secondpt = vec2(t.x,t.y)
                end
            end
            local newdist = firstpt:dist(secondpt)
            if newdist > dist and s < 6 then
                s = s + 0.1
            elseif newdist < dist and s > 0 then
                s = s - 0.1
            end
            dist = newdist
        end
    else
        tcount = tcount + 1
        if tcount == 1 then
            firstpt = vec2(touch.x,touch.y)
        elseif tcount == 2 then
            secondpt = vec2(touch.x,touch.y)
            dist = firstpt:dist(secondpt)
        end
    end
end

Hope that helps.

5

Good job, Vega! It works fine, thanks!

I feel like a beginner in Codea when I look at your code.

Thank you again!

6

No problem. Maybe someday I will clean that code up, it is more complex than it needs to be. Good luck with Codea, it is my new favorite toy.

7

If you want some more general touch handling stuff, I have some libraries for handling them. My code is available at http://www.math.ntnu.no/~stacey/HowDidIDoThat/iPad/Codea.html (a lot of it is out of date, though), specifically the file Touch.lua.

8

Just use my zoom library http://twolivesleft.com/Codea/Talk/discussion/550/zoom-library

9

I hadn’t seen this before, very nice. I will be using it in future projects I am sure.