# 2D Fishing line simulation.

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Hi, I'm trying to roughly simulate a fishing line. Therefore I basically have some evenly spaces points which are connected by lines. To create the initial set of points, I "throw" the line at a given angle and speed. I then have a moving point. If the distance between the moving point and the last "fixed" points is greater than a given distance, I fix a point at that position and I go on with the movement. Now, that gives me a nice curve. But now, when the very end of the line hits the water level, I want to "sink" the last point into the water and to pull the line, which is "hanging" in the air, behind it. Normally, the final result would be a straight line between the end of the fishing rod and the fishhook. Does anyone know how to achieve the "pull the line into the water"? And perhaps also the how to achieve the fishing line calculation when the player pulls in the line? Best regards, Metron

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I'll take a guess at this. There's a paper by Thomas Jakobsen that a lot of people reference when getting started with verlet-based physics - you can find it here. One thing about this method is that, for better or for worse, you can get some very nice effects with very little effort and without necessarily having a thorough background in physics. (Or course this can also get you into trouble!) What you've described so far sounds like it could be pretty close to the verlet + stick constraint method already, and that perhaps it could be extended to include the additional behavior you describe.

The method basically involves linking a series of particles with contraints; the particles are then acted upon by various forces, and also 'relaxed' so as to maintain, as closely as possible, fixed distances between them. In your case the particles would have an initial velocity due to the cast, and a constant downward acceleration due to gravity. The missing ingredient here is probably buoyancy, which you could implement 'correctly' as a force acting on the particles, or perhaps just hack in by decreasing gravity when the particle is below the water line. You may also choose to have the 'lure' end of the line (or whatever) have greater mass so that it sinks whereas the rest of the line floats.

To pull the line in, you would move the first particle, which is attached to the end of the rod. For more realism, the rod itself could be a series of particles constrained towards colinearity. It seems that with the proper application of fluid drag on those particles on or in the water, the rod would bend realistically as the line was pulled in.

Those are just ideas - I should make it clear that I only know a little about physics, and even less about fishing! :)

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Ah thanks... that looks good. I'll give it a shot.

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