Possible bug regarding lines in Breve 2.1

Hi!

I think I've might have found a small bug in Breve 2.1b. I have 
modified the RandomWalkers example to draw a line from any RandomWalker 
to its closest neighbour (in an inefficent way, just a quick hack). It 
seems to work just fine in Breve 2.0.1 but in 2.1b every random walker 
gets a line to every other walker. But, inspection of the walkers seem 
to indicate that they actually only have one line attached. Also, if I 
remove all attached lines (with self remove-all-lines) they are still 
left behind (altough inspection indicates that the walkers in fact have 
no lines attached).

This is the simulation I've used (the important change is in 
RandomWalker>>iterate):

#
# RandomWalker is a simulation in which small spheres do
# a random walk.  This is a very simple simulation which
# can be used as a skeleton for more complex simulations.
#

# include some required breve class files
@use Control.
@use Mobile.

# First tell the breve engine the name of our controller class

Controller myControl.

# Subclass "Control" and define our "myControl" object.

Control : myControl {
     # Here we define the class variables.

     + variables:
         walkerShape (object).

     # Next we define a method called init.  The init method is called
     # automatically when our class is created.  Since this is the 
controller
     # class, an instance gets created when we launch the simulation,
     # so this is the entry point for our simulation.

     + to init:
         print "Setting up the simulation.".

         self point-camera at (0, 0, 0) from (0, 60, 0).

         # set up a shape that all of the RandomWalker objects will use.

         walkerShape = (new Sphere init-with radius 1).

         # Create a bunch of RandomWalkers.  You can create as few or
         # as many as you want...

         10 new RandomWalkers.

     # The get-walker-shape is a method that allows other objects
     # to look at the walkerShape variable.  we do this so that
     # each RandomWalker object can reuse the same Shape object.
     # This is not strictly required--each RandomWalker could create
     # it's own copy of the same Shape, but fewer objects means
     # less memory used and more efficient simulations, so it's
     # a good programming practice.

     + to get-walker-shape:
         return walkerShape.

     + to iterate:
         #print "======".
         super iterate.
}

# The "RandomWalker" object is the physical object in the simulation
# that does the random walk.  It is a subclass of "Mobile".

Mobile : RandomWalker (aka RandomWalkers) {
     + to init:
         # During init, the object asks the controller for the shape
         # it should use.  It then sets itself to a random color.

         self set-shape to (controller get-walker-shape).
         self set-color to random[(1.0, 1.0, 1.0)].

     + to iterate:
         # Set a new random velocity at every timestep.

         self set-velocity to random[(60, 60, 60)] - (30, 30, 30).

         # Draw a line to the closest neighbour.
         # First remove all old lines.
         self remove-all-lines.
         # print "Closest neighbour to ", self, "is ", (self 
closest-neighbour).
         self add-line to (self closest-neighbour) with-color (1.0, 0.0, 
0.0).
         # self remove-all-lines.
         # print "Removed??".

     + to closest-neighbour:
         item (object).
         items (list).
         closestItem (object).
         distance (float).
         closestDistance (float).

         closestDistance = 1000000.

         items = all RandomWalkers.
         foreach item in items: {
             if item != self : {
                 distance = self get-distance from item.
                 if distance < closestDistance: {
                     closestDistance = distance.
                     closestItem = item.
                 }
             }
         }

         return closestItem.
}

-- 
Christoffer Karlsson
Väntar på Godot

_______________________________________________
breve mailing list
[email protected]
http://lists.spiderland.org/mailman/listinfo/breve