Linear Impulse

Questions
1

Hey Guys, I’m really new at Codea and try to use it for a school project.
So my Idea is, to have an actor ( a physical (dynamic) actor ( like a sphere ) ) in the middle of the screen at the begining. Then, if you tap the screen once one the right side, the actor jumps in a bow a bit to the right side and falls down, like in flappy birds. And if you press the left side of the screen once the actor should jump in a bow to the left side. So you can jump around in the scene. But i’ve got no idea how to realize it :confused: I read something about linar impulse on the actor, but i don’t know, how to give my actor physical behavours.
Can you please help me with this, is there a good tutorial for my problem? :slight_smile: would be nice
Thanks

2

Here’s something to give you an idea. Tap the left or right side of the screen.

function setup()
    b=physics.body(CIRCLE,50)
    b.x=WIDTH/2
    b.y=HEIGHT/2
    b.gravityScale=0
end

function draw()
    background(40, 40, 50)
    fill(255)
    ellipse(b.x,b.y,100)
end

function touched(t)
    if t.state==BEGAN then
        if t.x<WIDTH/2 then
            b.linearVelocity=vec2(-20,0)
        else
            b.linearVelocity=vec2(20,0)
        end
    end
end
3

There’s a lot of ways to do what you want, but without knowing what else you’re going to do I can’t tell you more than what I showed you above.

4

Here’s a quick mod that includes some fake friction.

function setup()
    b=physics.body(CIRCLE,50)
    b.x=WIDTH/2
    b.y=HEIGHT/2
    b.gravityScale=0
end

function draw()
    b.linearVelocity = b.linearVelocity*0.99
    background(40, 40, 50)
    fill(255)
    ellipse(b.x,b.y,100)
end

function touched(t)
    if t.state==BEGAN then
        if t.x<WIDTH/2 then
            b.linearVelocity=b.linearVelocity + vec2(-50,0)
        else
            b.linearVelocity=b.linearVelocity + vec2(50,0)
        end
    end
end
5

Actually, you don’t need fake friction. linearDamping can be used to slow the object down. The higher the value, the faster it slows.

function setup()
    b=physics.body(CIRCLE,50)
    b.x=WIDTH/2
    b.y=HEIGHT/2
    b.gravityScale=0
    b.linearDamping=1
end

function draw()
    background(40, 40, 50)
    fill(255)
    ellipse(b.x,b.y,100)
end

function touched(t)
    if t.state==BEGAN then
        if t.x<WIDTH/2 then
            b.linearVelocity=b.linearVelocity + vec2(-50,0)
        else
            b.linearVelocity=b.linearVelocity + vec2(50,0)
        end
    end
end
6

yes, i imagined there would be a way, though i didnt see it in the physics writeup. i had some point but i don’t know what it was … :smile: