So, I'm making a game where you have to use the webcam to control something that hits stuff, and I was wondering how to make it go where my hand goes on the webcam. Please help, bye.

when green flag clicked
forever
say [HELP!!!!!!] for (2) secs
end

Thanks!

this doesn't work:

adsuri wrote:

when green flag clicked
turn video [on v]
forever
go to (video [motion v] on [this sprite v])
end

and this is literally impossible to do:

ScratchDiogoh wrote:

when green flag clicked
forever
turn video [on v]
if <(video [video v] on [Stage v]) > (...::grey)> then // hand size
...
end
end

also, i don't think this is actually possible unless you have a bunch of clones all over the stage, to basically make a grid, and even then, it can only go to motion, not your hand.

See if this helps. Wave on the left sensor and and on the right sensor.

https://scratch.mit.edu/projects/237906575/

Scratch can only detect *motion* on a sprite/clone (or stage). It cannot directly ‘follow’ some specific object.

You can use the motion detected on the stage as a simplistic form of controlling a sprite – something like this, for example:

when GF clicked
set [Scale v] to [0.4] // this seems to give a reasonable speed for me
set [Tolerance v] to [35] // this stops it moving when motion is small
go to x:(0) y:(0)
turn video [on v]
forever
set [Stop time v] to (timer) // see the "when timer" script below
move by ((Scale)*((video [motion v] on [Stage v])-(Tolerance))) with angle (video [direction v] on [Stage v])
end

define move by (dist) with angle (dir)
if <(dist)>[0]> then // only move if enough motion was detected
change x by ((dist)*([sin v] of (dir)))
change y by ((dist)*([cos v] of (dir)))
end

when [timer v] > ((Stop time) + (0.5)) // A trick to turn off video after stop clicked
turn video [off v]

Note that above is simply detecting *any* motion over the whole of the stage – you can move your head, your hand, or even pick up the laptop and move it around so the whole background moves!


As DerpyHead0 suggested above, it's possible to use the motion-detection across a grid of clones to try to do some very crude following of a slow-moving object (as long as it's the *only* thing moving in that region).

Here's my attempt at head-tracking, for example:

https://scratch.mit.edu/projects/72290026/

Note that it really has no idea if what it's following is your head, or your hand, or some other thing – it's just making huge assumptions that you've followed the ‘rules’, put your head where you're meant to, moving it around not too quickly, and not got anything else moving around there…


One thing to note about motion-detection on a sprite/clone is that it's more expensive for larger costumes because it has to look at motion across the pixels of the costume. (That's why I used very small costumes for the detector clones in my project above.)

Conversely, though, the accuracy of the direction of detected motion becomes bad as the costume gets smaller – since there are fewer pixels for it figure out what's happening. (That's why I ignore the motion direction in the detector clones in the above project – it's unreliable.)

Finally, note that motion-detection is an expensive operation, so it'll slow down the frame-rate of the project – especially so if the lighting is not high. It's a really good idea to tell users of your project to make sure they are very well lit before running the project.


Hope that gives some ideas – and good luck!

DerpyHead0 wrote:

this doesn't work:

adsuri wrote:

-snip-

and this is literally impossible to do:

ScratchDiogoh wrote:

-snip-

also, i don't think this is actually possible unless you have a bunch of clones all over the stage, to basically make a grid, and even then, it can only go to motion, not your hand.

I know it was the only idea I could think of then.