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View Full Version : Divide Spline / Get Step Point Position?

 Kickflipkid68712-04-2010, 09:20 PMHello again, I'm trying to find a way to either: A - Get the Position of each Step Point in a spline or B - Divide a Spline so that the knots match the step count so I can get those positions. Anyone have any ideas? Thanks! -Matt
denisT
12-04-2010, 11:51 PM
A - Get the Position of each Step Point in a spline
B - Divide a Spline so that the knots match the step count so I can get those positions.

my simple question is why do you need it? if you want to know where the vertices will be after conversion the spline to the mesh you can just to convert. if you want to know the best linear approximation you can do it yourself.
well... what is your ultimate goal?

Kickflipkid687
12-05-2010, 01:41 AM
I was trying to figure out a way to most easily let the user make a spline of sorts, and then use that to align a plane that was segmented to each of those spline steps.

Basically like if u turned on render in viewport on a spline, and made the spline with the rectangular option, so you have the mesh flowing along the spline.

I need to get that mesh, but only have the top faces left over at the end, so I can work with those faces to do insets and such. But I'm not sure how I could say to delete the other faces and keep the top ones....

So that's why I was going to use a plane that was segmented based on the spline steps, then align each segment on the plane to the spline segment, if that makes sense.

Edit: Trying to get only these top faces left over after converting to an EPoly Mesh.

http://dl.dropbox.com/u/6895456/leftOver.jpg

thanks

Kickflipkid687
12-05-2010, 05:25 AM
Actually I think I solved that issue.. with selecting the top faces :).

It seems like Face #1 is always on top, which is good to know.

So then what I decided to try was , get that face Normal, since the other faces normal Z axis should be almost identical across the top, no matter if they are rotated or not.

So to make sure I select all of them, I just used a dotnet function to round those Normal.Z Values collected, to .1 decimal places , and then I collect those faces into an Array that match that value.

So ... so far it's working as expected :D

denisT
12-05-2010, 04:32 PM
probably I don't understand the problem well.
To convert the spline to mesh is easy. Top faces are based on only N (number of sides) first vertices. It's easy to find them. The normal of a top faces has to be the same as tangent of the spline in this position. If you set Thickness(Radial) or Length and Width(Rectangular) to 0, you will get sets of N verts in position of every step.

What extra information do you need?

jonahhawk
12-05-2010, 08:48 PM
I know this is a scripting forum, but it seems you are looking to create a single ribbon type geometry from a drawn spline. You can use a sweep mod with a custom profile that is simply one line segment. Or even Loft if you want to change the scale or twist over the length of the path.

Also, Ghost Trails (http://www.ghosttrails.net/index.php/gallery.html) will create geometry like this.

Honestly I would love to see the scripted solution here. Denis' comments about the top faces in relation to the spline tangents are interesting. I'd like to learn more about that in an attempt to control spline twisting on sweep or loft paths... some time... when I'm not working on a Sunday.

Kickflipkid687
12-05-2010, 09:46 PM
hmmm... Thanks for the info dudes. I will look into that stuff for sure :).

I achieved what I wanted to do however. Although it may end up being I need to change some methods, but so far so good.

http://www.matthewlichy.com/strip/rumbleStrip.html

Edit: That sweep mod is awesome :D. I've used max for like 10 years and have never used that before. Very cool stuff :)

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