Rollercoaster is killing me

Hi Everybody,
I need Help, Script, Plugin or any Suggestions for technical Approach to achieve the following Task:

A Rollercoaster with very chaotic Curves and Loopings(not realistic) , which is building itself (growing / appearing), while a camera is following from the side.

I modelled the Mesh of the Rollercoaster and formed the Track with a Spline.
With the Pathdeform modifier i put the Geometry on the Spline that was easy.
The Camera following the Rollercoaster is also set up and everything is fine

The Problem is i dont know how to make the Rollercoaster "grow" while the camera is flying by its side.
My Approach so far:

1. Slice modifier, following a Dummy that is also running along the Rollercoasters Track. Problem, the Slice Plane has infinite Dimensions and is also Cutting away parts that have already been revealed (especially in Curves) and is very difficult to control
Seems this Method is only suited for straight long Objects with no Curves at all.

2. Black White Gradient as Texture in Opacity Slot, that is animated with a UVW XForm Modifier along the Rollercoaster, Problem: i would need the whole Rollercoaster as one piece of Geometry to give working UV Coordinates. That is not possible because i have to chop the Rollercoaster in many pieces to controll the rotation and orientation of the Rails in the Curves

3. Not tested yet, another Geometry (eg. Cylinder is covering/blocking the whole Rollercoaster like a Tube or Hose and is animated to reveal the Trails as the Camera is moving along. The Material would be a matte shadow that doesnt create an Alpha, so i would get the Alphachannel of the Trails only which i could use as Mask in Compositing. Problem here also, the Tube would block out Pieces of already revealed trails when the Camera is moving in some angles.

I wonder if there is no better Method because i think its more like a basic Task....nothing to crazy ?!?
Just animating the Rollercoaster itself with pathdeform is not the Solution because the Trails should not move itself.

i would really appreciate any kind of help or suggestions an believe me i searched an googled a lot already. Maybe im to Stupid to find the right Script or Tutorial and if you know that "right one" please let me know

Thx alot if you read this far!


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br0t's picture

Hey thanks for posting this.

Hey thanks for posting this. It is definetely the right place to post here, as I, for example, find myself searching in old posts for something specific quite often and I am happy when I find a solution, no matter if it is a script or a description like yours. Glad you solved your problem, cheers!

Never get low & slow & out of ideas

Caliber762's picture

Got the Solution

Ok seems like nobody cares or nobody knows, i guess first :)...anyway just in case someone is stuck in a similar Situation here is how i did it.
I wonder if i should put it here because its not script related at all but maybe it helps

1. Model Geometry Rollercoaster (does not have to be one piece, mine consists of 9 Parts)

2.Put Tracks on Spline with Pathdeform, adjust rotation and twist as you need in the modifier. When the whole thing looks like you want, note all parameters:Percent along spline, rotation , twist etc for each piece of the Rollercoaster as a backup

3.Deactivate Pathdeform mod.(not delete), Place , rotate track pieces so you can apply an unwrap modifier (cylindrical).

4. Make a Material with Gradient Ramp (black n white) in Diffuse and apply to Track pieces. Tweak the uw offsets so you have one side of the track black the other white. Adjust the transition of the ramp according to the way the Track should appear (soft/hard). If you like the look, drag the material from Diffuse slot to Opacity slot and make it an Instance. Now the Black parts of the Ramp should cut off the track.

5. Adjust and tweak the Texture with an uvw Xform modifier for each track piece (maybe turn opacity on again for better judgement) so its possible to make one piece complete white or complete black (you have to try settings, tiling and offset in the uvxform modifier, not in the material itself.

6.Make a new Blend Material. Put the Material that you want for the track in Slot 1. Make a standard Material with 0 Opacity for slot 2 and use your created Ramp Material as the Mask.

7. Reactivate Pathdeform modifier reenter the correct settings for percent along Path, rotation, twist etc (in case you changed them for unwraping)
Important! Click on "move to path" again for each track piece after reactivating the Modifier or you will have a slight offset. Now your Rollercoaster should look like at the beginning

8. Animate the growing Process with the uvw xform modifier "offset" For better judgment apply only the ramp Material and set your Keyframes, when everything is fine switch to the real Track Material and Render.

Also works if Track consists of different Materials u have to use Mat ids and put the different materials in a multi sub material.

Of course u could first apply uvs and then put on track with pathdeform, but in my case i had to first figure out how long the pieces of the track would be. Also maybe not the best way to achieve this but it worked for me and was not to much trouble.


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