On-the-fly line slow update

[willpower2727]

I'm streaming x-y-z coordinates from a camera system (120 Hz) and using them to update the position of a small sphere (like a cursor for a mouse). I am attempting to show a trace history of where the cursor has been by using onthefly line vertex like this:

global tracer
viz.startLayer(viz.LINE_STRIP)
viz.vertexColor(viz.YELLOW)
tracer = viz.endLayer(viz.WORLD,viz.MainScene)
tracer.dynamic()

while TRUE:#while data is streaming in...
    cursor.setPosition(X,Y,0.98)
    tracer.addVertex(X,Y,0.98)
end

What I observe is the cursor keeps up with incoming data (it keeps up in real time). However the line exhibits periodic gaps of 2-4 seconds of missing data but the rest of the time it works well. I've tried two things to remedy:

1. I hoped that tracer.dynamic() would help, the documentation for this function has no elaboration so I don't even know what it does.

2. I've tried to reduce the sampling frequency down to 60 Hz, no change in behavior.

The real questions I have then are

1) Why can the sphere change positions quickly but adding line vertices cannot?

2) Why are there seemingly random gaps in adding vertices to the line? Any ideas?

Thanks!

[Jeff]

Try registering a callback function using vizact.ontimer that gets called on a regular interval. Then within the function draw the vertex.