View Full Version : spiral path around a hill - How?

Mr Mouse
04-11-2005, 05:11 PM
I've been trying to create a spiral walkway, cut into and running around the outside of a hill.

How can I cut walkway/path into a hill and then indent the path so it looks like it's worn down into the hill.

I'd ideally wish to subpatch it also.

Any advice would be greatly appreciated.

Yours Mr Mouse

04-11-2005, 05:45 PM
Hmmm... What if you created an L shaped object and lathed it as a spiral around your hill. Use this to boolean subtract part of the hill. This peace may need to be tapered to make smaller towards the top of the hill.

Mr Mouse
04-11-2005, 07:41 PM
Dear Silkrooster,
Many thanks for your reply.

I tried your suggestion with lathing the shape into a spiral and tapering it to the hill but seemed to run into a problem when attempting to boolean the hill.

The picture below shows that error on my part and also a wee sketch of the effect I'm trying to replicate.

Ideally I'm hoping to cut in a path and clone trees along the spiral of the pathway.


04-11-2005, 08:06 PM
Try to model it in layout.
Use a texture displacement map on a plane well subdivided.
In Photoshop (or other paint program), you can make a gradient of white hill and black bottom, then make another with a slightly lighter gradient on the bottom to a slightly darker one on top (so your base layer is 255,255,255 (white) in center of pic and 0,0,0, (black on outer edges) your second gradient will go something like 240,240,240 and 10,10,10 (play with these numbers)), draw your spiral on another layer, and use that to 'Take away' everything but what is under your drawn spiral in the lighter gradient, so you end up with a spiral path that goes from dark (bottom of hill) to light (top of hill).
Now overlay that spiral on the original gradient, flatten image.

in Layout, bring in the well divided plane, use the pic as a displacement map.
You'll see a hill form with the trail spiraling around it to the top.

depending on how the difference is between your original hill and the spiral, will be the depth of the trail. So you may have to play with the spiral gradient a bit to get the right shade of gradient.
But it will give you a trail that has steep sides on the uphill side of trail and a falloff on the downhill side and a flat pathway.

The more the plane is subdivided, the better the results.

A slighht edge blur on path layer in photoshop will roung off the edges some (depending on the blur used).

But it will work and get you what you want.

04-11-2005, 08:46 PM
Ok I tested to make sure of what I speak ;)

So here is what I had
Base Layer
Secondary gradient
drawn spiral
removed trash
merged layers
then layout test

as you can see it will woprk, giving you flat trails spiraling up the hill.

Now this was extremly roughed out, with no care taken anywhere, so pic is well pixelated (72dpi I think)

So take your time in Photoshop and get good pic to work with, then subdivide greatly in modeler (you can go back and do a lessen polys later in modeler on your object).
Anyways here thay are.
ARGG only 5 pics at once...........

04-11-2005, 08:47 PM
And the hill

04-11-2005, 08:53 PM
just thought that if you ALSO do a color map of the spiral with a totally black line with white stripes or yellow dots down the middle for the full lenght and saved it, you 'COULD' have the roadbed texture for a 'Pikes Peak' type hill with road winding around to the top.

Also don't forget that if you invert the pic in layout, it will give you a road down into a crater too.

04-11-2005, 09:17 PM
I guess theories don't always work. Oh well, I didn't even think about doing a height map. That's why prospector, is da man. :D

04-11-2005, 09:20 PM
....... :D

04-11-2005, 09:38 PM
Boolean subtraction almost works, but it has to be a flat plane instead of L shaped and it must be perpendicular to the hill. It also needs to be high enough so it does not have a ceiling once subtracted. The problem that I did run into using this method is there is a wall at the start of the slope. Oh I was so close. :p

04-11-2005, 11:27 PM
Also you end up with nasty numbers on the polys like 3s and greater than 4s
whereas on the above it's all quads

04-12-2005, 05:20 AM
My first thought is "Use the Seashell Tool" (Multiply->Extend->Seashell) because it extrudes geometry in a diminishing spiral.

I'm not sure how it would be best used, though. I'd have to experiment.


UPDATE -- Yeah, Seashell can create the geometry you described. Attached below is a screenshot of what I created in Modeler with the Seashell tool, and a layered object showing each step I took to get to that point, with the finished model in layer 10. Steps taken:

1) Create a 2-point polygon

2) Use the Seashell tool to extrude a diminishing spiral

3) Flatten the results with Set Value, Y=0

4) Merge all near-overlapping points with the Merge tool at a "Fixed" setting

5) Fill in the hole in the middle

6) Split the polygon formed in the middle into 3 and 4-point polygons

7) Use the Pole Evenly tool to scale the points outwards, so that it looks a little bit more like a flattened hemisphere.

8) Use the Magnet Tool to push these points upwards into a hill-shape.

9) Select the points around the "hem" that aren't touching the "floor," and use Extender Plus + Set Value to create new geometry that does touch the "floor"

10) Hit Shift-I to Unify the redundant polygons created in step 2 (any time you extrude a 2-point polygon, you get a redundant duplicate of the 4-point polygon(s) generated). Use the Bandsaw tool to add extra geometry for your path, and use Select Loop (if you need to) to select these points and Stretch them outwards from the center in the Top view, to form the path. Then use Bandsaw again to add strips of geometry at the edges of the path. This will keep 'em sharp for SubD's. Then hit Tab to turn everything into subpatches.

The trickiest part for me was the Bandsaw part, because if I didn't watch it the Bandsaw would down the side of the hill after running up the spiral. This was because I didn't pay attention to the geometry at the end of the "road" that Bandsaw had to travel -- and there was a four-point polygon at the end of the path that "aimed" Bandsaw down the side of the hill after Bandsaw got to the top. Tripling that four-point poly marked the end of where I wanted Bandsaw to go, and it stopped that problem.

I hope this post proves useful.

Mr Mouse
04-12-2005, 06:38 AM
prospector - many thanks indeed for taking the time out to offer your assistance. The screenshots are most welcome and always make understanding so much clearer.

I hope to try your method this evening and see what I can come up with it certainly seems like the method that may offer the most soft and organic feel. Much appreciated.

Celshader - many thanks for your advice. As I'm writing this I see you've posted an updated description of your technique so I'm keen to give this a whirl also . I'd just tried your initial method described using "seashell" on a single 4 point poly and must say that it gave very passable results particularly as landscape geometry in a background scene as opposed to foreground detail. Some hand tweakings I'm sure would improve upon my very simple test that I've attached here.
Many thanks.


Celshader - wow!
just posted this and then spotted your image update. That's exactly the effect I was after! Most exciting - I hope I can retrace your steps.

04-12-2005, 10:02 AM
Good one Celshader!
Forgot Seashell was there (tho I don't think I ever used it cept when it first came out, said "that's cool" and forgot about it).

So many different ways to do stuff in LW................ :)