If it has bones then pretty sure you could use a rigid body constraint to connect them together
The gangway bends so I need it to move around and the bones to move when the train turns corners, not to be fixed in place.
Look at some other constraints then. but just try it out
I have thought of an idea that ‘could’ work.
I’ll get back to you soon.
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Never mind, I was working on some silly math formula but I don’t think it was right.
I think it would be something similar to “Quad Curve” but I don’t know how I’d get the control point.
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im pretty sure the control points are something you define yourself
Yeah, I think so too but I want to make it so the game would figure it out itself because the position will change depending on how far it’s turned.
You can possibly get the Control Point by using the same methods as in this topic.
Though this might be over-complicated to just get a curve.
Looks promising but, I’ll probably have to spend a few days working on this. I’m about to go to sleep now so people may have other solutions that are easier.
This is something I just asked chatGBT
To find the control point (also known as a Bezier control point) between two points, you need to specify how you want to create the curve between those points. In most cases, you’ll be working with quadratic or cubic Bezier curves. Here’s how to find the control point for both cases:
-
Quadratic Bezier Curve:
- Given two points: P0 (start point) and P2 (end point), and you want to find the control point P1.
- Calculate P1 as follows:
P1 = (P0 + P2) / 2 - P1 will be the midpoint between P0 and P2.
-
Cubic Bezier Curve:
- Given two points: P0 (start point) and P3 (end point), and you want to find the control points P1 and P2.
- Choose two other points P0’ and P3’ that are close to P0 and P3, respectively.
- Calculate P1 and P2 as follows:
P1 = P0 + (P0’ - P0) / 3
P2 = P3 + (P3’ - P3) / 3 - P1 and P2 should be placed one-third and two-thirds of the way between P0 and P3, respectively.
The choice of P0’ and P3’ can depend on your specific requirements, but typically they are chosen to create a smooth curve. You may experiment with different values to achieve the desired curve shape.
Keep in mind that the control points determine the shape of the Bezier curve, so the placement of P1 and P2 will affect the curve’s behavior between P0 and P3.
Does anyone have any other solutions I can try?
I can’t seem to get it to work.
Get the center of position between both positions, 2 Vector3s so that’s easy:
local center = (position1 + position2) / 2
Pretty simple, then you would need to push this point on X/Z axis depending on the movement of the train, say you have the direction in which the train is turning as a vector3, we can do this:
local offset = turnDirection.Unit * curvature
And the final position of the center point is just
center + offset
For the side that’s closer to the center of rotation you will use -offset as it needs to go inwards and not outwards. I came up with the math right now so it may or may not work lol, it theoretically should though… After u have this “center” point you should be able to move the mesh, you said you had bones so afaik it’s easy to do it with that, I’ve never worked with bones though.
I didn’t tell you how to calculate curvature so I’ll guess you don’t know and tell you, in case you already knew u can ignore this part.
We first need start and end of the curve, Y-axis is ignored as we don’t need that, the train won’t drive upwards or downwards, will it?
local curveStart = Vector3.new(x1, 0, z1)
local curveEnd = Vector3.new(x2, 0, z2)
We need to calculate the slop, m, now, it’s the same as 2D graphs, our 2D plain is X and Z (X and Y in normal 2D) so it’s pretty easy, instead of doing (y2 - y1) / (x2 - x1) we will do (z2 - z1) / (x2 - x1)
local m = (curveEnd.Z - curveStart.Z) / (curveEnd.X - curveStart.Y)
We now need to calculate the perpendicular bisector, it’s pretty easy. Perpendicular bisector is the line that intersects the original line at a right angle and passes through the midpoint of the line segment between the two points.
local midpoint = (curveStart + curveEnd) / 2
local perpendicularSlope = -1 / m
local perpendicularBisector = midpoint.Z - perpendicularSlope * midpoint.X
Now we calculate the center of curvature on each of our axes.
local centerOfCurvatureX = (midpoint.Z - perpendicularBisector) / (2 * perpendicularSlope)
local centerOfCurvatureZ = perpendicularSlope * centerOfCurvatureX + perpendicularBisector
And now the the radius of curvature (distance from the curveStart to the center of curvature).
local radiusOfCurvature = math.sqrt((curveStart.X - centerOfCurvatureX) ^ 2 + (curveStart.Z - centerOfCurvatureZ) ^ 2)
And last but not least we calculate the actual curvature
local curvature = 1 / radiusOfCurvature
Full code:
local curveStart = Vector3.new(x1, 0, z1)
local curveEnd = Vector3.new(x2, 0, z2)
local m = (curveEnd.Z - curveStart.Z) / (curveEnd.X - curveStart.X)
local midpoint = (curveStart + curveEnd) / 2
local perpendicularSlope = -1 / m
local perpendicularIntercept = midpoint.Z - perpendicularSlope * midpoint.X
local centerOfCurvatureX = (midpoint.Z - perpendicularIntercept) / (2 * perpendicularSlope)
local centerOfCurvatureZ = perpendicularSlope * centerOfCurvatureX + perpendicularIntercept
local radiusOfCurvature = math.sqrt((curveStart.X - centerOfCurvatureX) ^ 2 + (curveStart.Z - centerOfCurvatureZ) ^ 2)
local curvature = 1 / radiusOfCurvature
Too long? I’m just as surprised as you are! Lmao
Uhm, my eyes hurt from this… I’m not too good at math (not this sort of stuff at least). Could I give you like a model of the thing and get you to do it for me? lol (Not being lazy… well, maybe I am but this is too much for me lol)
Lmao, can’t blame you. As I mentioned before I haven’t worked with bones so I don’t know how to make them bend or all of that. Just copy the last code at the end and read the start and you should be good to go.
Lol.
I haven’t worked with bones either so its something I’ll have to learn and this might not even work for it but I think it might but I think bones are just the exact same as attachments (which I’m using as a test) but maybe with some changes.
Ok, I’ll try lol
Wait, how exactly do I position all 12 attachments on each side?
U can use lerping between center and start for 6 then center and end for the other 6
Lol, I’ll come back tomorrow or something because I’m too tired for this now lol (Its 9PM for me so that’s why).
Aha, it’s 11:30 am for me so that’s a really lovely time zone difference lmao. Good luck.
One idea can average the right vector to get your control point p3 for a curved line.
Another idea is to use a circular arc like beam bending and look to other similar curvature problems like curved roads
Wait, are you any good with bones in blender? If so then would my little idea of adjusting the bones positions like the way im going to for the attachments the best idea?
For circular arc, is this using a completely different method for the gangway or is this another way for positioning the attachments?
You asked me on another topic whether or not using Vector3Curves was a good idea to be used here. Don’t want to veer off topic there so I’ll add a reply here, but I wouldn’t use Vector3Curves for this personally.
It might be more worth it to just use a quadratic bezier, and use an average point as your control point as @dthecoolest said, or you could use a line intersection algorithm to find where the two points would intersect and use said intersection point as your control point.
Creating a whole spline is going to overcomplicate things, and you will not get the result you expect because Vector3Curves pass through each control point while bezier curves do not.
Your conveyor would end up more or less looking pretty, uh, wiggly I guess for lack of a better word, because the spline has to pass through each control point.
It would look even worse the more acute the angle is