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# SOS_What is the meaning of the "tangent" in Spline? and what about the relation between tangent and curvature?

I am working on my own train-simulation project

I tried to use spline to definite the railway, and use the spline mesh component to do the visual job.

In order to prevent the mesh of the rail from being overstretched, I want a series of spline meshes to be covered with a control spline with a fixed length, but in practice, I find that if I use the tangent of the control spline as the tangent of the spline mesh, the spline mesh will be greatly distorted.

I want spline meshes to cover the control spline with the same curvature. I don’t know what to do. Maybe I need to find the relationship between the tangent of spline and the curvature of spline in UE4

(Sry for the broken English…

Hi all,

I have a very simple construction spline of 6 control points with a spline mesh component. This gives me a nice smooth mesh that follows the spline but unfortunately since the spline points are not evenly distributed the mesh components are stretched at different lengths. So to fix this I created another spline from the construction spline with more points that are evenly distributed then again applied a spline mesh component to get a mesh that follows the spline. This gives spline mesh components that are equally sized (not stretched) but unfortunetly it introduces “pinching” and “warping” in each mesh. Hopefully the images below explain better…

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The reason I think this is happening is due to the tangents, basically I am not sure how to get correct tangents for the new subdivision points created? I have tried getting a normalised tangent at point/distance and multiplying it with the length of each section and that give me the results above, I have tried setting the points to curve, curve clamped, curve custom tangent, etc.

If any maths/programming experts know the correct way to do this, I would greatly appreciate it.