Re: [pygame] Pygame, cwiid and ode - movement

["Nathan Whitehead" <nwhitehe@xxxxxxxxx>]

On Thu, Aug 7, 2008 at 2:39 AM, flx <xf3l1x@xxxxxxxxx> wrote:
> I'm trying to make a foosball [1] game wth pygame, using the wiimote
> to control the bars.
>
> I've managed to control the rotation using the accelerometers, but i
> can't get the sliding part right. I've been asked to use the ir
> sensors for the sliding movement, but I just can't get it right.

I think you have two separate questions here:
* how to get IR working on the wiimote and get IR data
* once IR is working, how to interpret the data to make the paddle
slide around correctly

For the first part: which Wiimote library are you using?  Does it
support IR?  Is it buggy with your particular Wiimote/bluetooth
combination?  What operating system are you using?

For the second part: I recommend making a simple program that just
displays squares at the reported IR positions, setting the screen to
1024x768.  Then try moving the Wiimote around and take notes about
where the squares go.  Where do they go when you slide left?  What
about when you point downwards?  Rotate clockwise?  Then use those
notes to write code to control the paddle directly.  You might need
some calculations here (argh, math!).

Once you've got this down you will have control of the paddle but it
will be jerky and flickery.  Also when you move too far to the edge of
the screen the paddle will stop moving (one IR dot goes off screen).

To fix the jerkiness, a first step is averaging several values over
time.  A better but harder approach is a Kalman filter.

To fix the flickery problem: if there are 0 dots reported, use the
most recent positions.  That stops the input from disappearing for a
frame.  If there are too many dots (3 or more), then you want to pick
the 2 dots closest to the last reported IR positions.

To fix the edge-of-the-screen problem, a good approach I've used is to
guess where the missing IR dot should be.  I assume that the dot off
the edge of the screen moves just like the one that remains on the
screen.  This won't be strictly true if the wiimote is rotating or
changing distance to the sensor bar, but it will keep the paddle
responding to input rather than stopping abruptly at the edge of the
screen.

FYI: I'm working on a pygame library that supports the wiimote on all
platforms, it will be done Real Soon Now.
--
Nathan Whitehead