Tckgen iFOD1 fix max angle at seed master#3335
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Mostly indentation changes, but also minor cleanup in handling of init() method.
With iFOD1, the second half of a bidirectional streamline starts in the opposite direction from the first half. The seed direction is determined first, and then used as the initial direction of tracking for both halves. But the actual direction of the first step is taken as a random sample within the angular constraint about that seed direction, and because this happens both ways, and with the same seed direction, it is possible for the angle between the two line segments either side of the seed point to be up to twice the max angle. The solution here involves setting the initial direction of tracking for the second half of the streamline to the (opposite of the) *actual* direction of the first step of the first half, rather than the seed direction initially determined. This ensures that the first step of the second half of the streamline is taken within the max angle constraint of what is effectively the incoming direction of tracking. To achieve this, the reverse_track() method was extended to perform the actual track reversal and set the position and initial direction of tracking, and overridden in the iFOD1 method to set things appropriately.
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Supersedes #2325 by targeting
master.I'm initially creating this as a draft PR.
My instinct is that this requires a little bit more tweaking.
Desired behaviour for both first-order and intrinsically second-order methods RE tangent at track reversal:
method.dirafter the completion ofinit()that needs to be loaded in as the content ofmethod.dirafter reversal, but the direction of the first step.It seems that the behaviour of iFOD1 vs. iFOD2 with a user-specified seed direction is quite different.
next()is called it's doing the same thing again. So the actual tangent of the first step could be outside of the permissible angle from the user-specified initial direction.Perhaps the correct behaviour is to check whether it's feasible to find a direction at the seed point relative to the user-specified seed direction, and if a suitable direction can be found, then the seed point is accepted, but
method.dirremains equivalent to the user-specified seed direction. That way, on the first call tonext(), the direction of the first step remains within the permissible angle relative to the user-specified seed direction.