Part A. Trail Rig:
1. Create the trail Geo with 20 segments on a polygon.
2. Put 21 joints on both sides, hirarchy from top to bottom. Name them accordingly.
3. Weight the Geo to both joint groups. (select those 2 joint group roots and then select the geo, smooth bind)
4. Create CV curves for both joint groups, with 5 CVs respectively snapped on the 1st, 6th, 11th, 16th, 21th joints.
5. Select the first joint and the last joint, then select the curve, create Spline IK with "auto create curve" UNCHECKED, do it for both sides.
6. create a cluster for each CV, in total 10 clusters on both sides (select CV, create deformers -> cluster)
7. create 10 locators and snap them on all 10 clusters respectively. Name them accordingly.
8. Select the locator then the cluster at the same location, hit Point Constraint with "offset" unchecked.
9. You might have found that this rig has to be strechy and squashy, people would do it differently since there are so many ways to achieve it. The way I did is create curveInfo node on the spline curve, then set expressions to make all the joints scaled on Z according to the times the spline curve length is modified.
Part B. Trail Texture:
- This is the ramp1.
- conect fractal1 to the gray part on ramp2.
- conect ramp2.outColorR to blendColors1.blender
- conect ramp1 to blendColors1.color2
- blendColors1.color1 has to be white.
- conect blendColors1.outColorR to lambert2.transparencyR, do the same to G and B channels
- the Ambient Color on lambert2 has to be white.
- the Color on lambert2 can be any color you like to see on the Trail.
Part C. Animation:
- before getting into this part, save the trail file as a reference, then import to the scene with the animated paint roller.
1. go to the first frame of the scene, create 2 locators and snap them at the points that look generating the Trail. Name them properly.
2. point-constrain all locators in each row to either locator on the roller-head. Do the same to the other side.
3. bake the animations of all channels on all locators of the Trail.
4. offset the keys of those locators 1 frame after the previous ones, so all 5 keys on each side will be at the 1st, 2nd, 3rd, 4th, 5th frame respectively. As a result, the Trail Geo will track in the same way.
