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1. ## Cant / superelevation and Path3D normals on a helix/spiral road/rail

Hi all, This may be an easy question but I cannot seem to solve it myself after several attempts. For my Model Train Simulator in BabylonJS I'm creating a helix/spiral track, allowing trains on a lower section to quickly gain altitude within a short area (e.g. climbing a mountain). This is often used in 'hidden' sections on model train displays to have a train pass a valley track and next pass a mountain bridge which is position much higher (Y position) in the scene. When I construct the points of a helix/spiral using the formula from the docs https://doc.babylonjs.com/babylon101/parametric_shapes https://www.babylonjs-playground.com/#165IV6#61 And then use Path3D on these points to get the normals see the docs https://doc.babylonjs.com/how_to/how_to_use_path3d https://www.babylonjs-playground.com/#2DLXYB#1 https://www.babylonjs-playground.com/#8ICWNU Then I get an ever increasing cant/superelevation of my track, see the blue arrows in the picture which indicate the 'up' vectors. The result is that the track at the top has a cant. I use the Tangent, Normal and Binormal from the Path3D of the line/points to set the track rail and bed geometry, and position the train always perpendicular to the track (that is: up). But I want to have the Up vector always Vector3.Up(), or at least that there is no cant/superelevation and I can continue placing 'flat' track with it's normal Vector3.Up() on the top. The big blue arrow indicates Vector3.Up(). Current 'vector up' results from Path3D in my game: Blue = up vector (from Path3D). Large blue with _ = helix direction (Y axis) Yellow line through track = Line through the spiral center points (radius * cos t, radius * sin t, ascentfactor * t) Desired 'vector up' on the spiral/helix: (image found at http://www.easyhelix.com) Hope someone knows how to 'alter' the results from Path3D so I get the helix point orientation but without the cant/superelevation. So that I can 'lay the track' properly without trains 'falling off the track' because of cant/superelevation. Bonus questions: - the yellow marked area in the skybox marks another bug that is caused with a reflection texture intersection with the skybox. the default background color comes through on the waves. - the red box marks a mesh (air balloon) with a physics impostor that is already moving, but I want the physics computation to be paused until the user presses some 'start to play'-button, instead of physics computation right from the moment the scene is loading Happy coding, Q