Post Fri Apr 13, 2007 1:43 pm

What are a THN curve''s values?

As everyone who has looked into THNs a bit more extensively knows, curves for events are made up of points looking like this:

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The first two values are position coordinates, I know that much. The last two values somehow hold the curvature of the whole thing. I have found out that the third value is responsible for curvature in front of the point and the fourth value is repsonsible for curvature behind the point. I also know that positive values make the curve bulge out away from the point and negative values make the curve slimmer by moving it closer to the point. Also, the higher the values, the longer nothing happens while the curve approaches the point, but then the change happens more abruptly the larger the value.

Moreover I know that having curvature values of zero still maintains a slight bit of curvature. And the last thing I know is that by having extremly large values, you can create a kind of overshoot, with the value becoming larger that you originally wanted.

Now, I am at a loss what exactly these two curvature values give. I have looked for some relation to the smoothing tangents of the point, but found no logical connection in that direction, yet. I mean, the thing is that one value describes the curvature for one side of the point. So it can't simply be the tangent handle or something like that, since that would require two values a point.

I've considered it might be some form of NURBS or Bezier data, but I admit I haven't got a clue about those, other than that they don't need four values for a point. So I pretty much dropped the idea this could be a NURBS or Bezier format. But I could be wrong here.

The question is: Does anyone have only the slightest clue what values these two last numbers hold? Has anyone made some research into that direction? I'd be happy to recieve some inspiration here, since I really have no idead right now what this could be.