Re: [Billiards-devel] Programming experiments with Billiards

[Tadej Janež]

Hi,

just a quick reply because I'm currently stuck...

I'll reply to the other parts later.

On Wed, 2010-01-13 at 14:33 +0200, Dimitris Papavasiliou wrote:



>         Ok, perfect. This is what I needed.
>         
>         Now, I tried setting observer's position with something like:
>           bodies.observer.longitude = -1.42
>           bodies.observer.latitude = -0.71
>           bodies.observer.radius = 0.4
>           bodies.observer.elevation = math.pi / 2 -
>                           bodies.cue.elevation -
>                           math.rad (5)
>         
>         
>         but it didn't work. Basically, I want to change observer's
>         direction
>         like you do with holding down the left mouse in the looking
>         mode.

> Anyway your problem is probably caused by the fact that one of my own
> hooks fires after yours and resets the observer heading back to the
> way *I* like it.  Pretty annoying innit?  You'll have to sort that
> out... :)

Ok, I think I found the "offending" code in game.lua, lines 177-178. Now
I can set the observer longitude and latitude.

I also managed to set the observer's azimuth with this code
local oldnewshot = billiards.looking.newshot

billiards.looking.newshot = function ()
   -- First call the old function to setup the default
   -- behavior we don't want to change.

   oldnewshot()

   -- Now change what we don't like.
   bodies.observer.azimuth = math.rad(90)
   bodies.observer.elevation = math.rad(45)
   bodies.observer.longitude = bodies.cueball.position[1]
   bodies.observer.latitude = bodies.cueball.position[2]
end

> Well it calculates the length or magnitude of a vector.  So this would
> result in the speed of the ball in m/s regardless of its direction of
> motion.

Aha, thanks for explaining that.




>  There's currently no mechanism I know of that allows you to switch
> modes programmatically.  It shouldn't be hard to improvise one though.
> If you look inside ball.lua you'll see that there are some event nodes
> linked under each ball (with switch or button nodes on top of them)
> which catch the mouse clicks on the balls and either switch the active
> cue ball or enter aiming mode if the clicked ball already is the cue
> ball.  Just put the code that enters aiming mode in a function of your
> own and call it from wihtin your script to get rid of the need to
> manually click the ball.  Next move the cue as you already do to shoot
> the ball and then wait until you no longer are in waiting mode.
> Lather, rinse, repeat.  I'm not sure if this will work but it seems
> likely.  I'll have to try it out myself when I get the time.

Ok, I tried to implement the transition between looking and aiming mode
with the following:

if options.experiment2 then
   billiards.looking.experiment2 = function ()
      for i, ball in ipairs (bodies.balls) do
         local x = ball.position[1]
         local y = ball.position[2]
         if i == 1 then
            print (string.format ("White ball position: (%f, %f)", x,
y))
         elseif i == 2 then
            print (string.format ("Black ball position: (%f, %f)", x,
y))
         end
      end
      print ("Entering aiming mode...")
      bodies.observer.islooking = false
      bodies.observer.isaiming = true
   end

   billiards.aiming.experiment2 = function ()
      print ("Stepping into function 'billiards.aiming.experiment2'")
      joints.arm.motor = {arm_velocity, 1000}
   end
end

but it doesn't work. The console output shows the text:
"Stepping into function 'billiards.aiming.experiment2'", but the balls
don't move.
Can you help me with this?

Greetings,
Tadej

-- 
Tadej Janež <address@hidden>
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