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View Full Version : How to Extrude a Curve?


CrimsonGT
02-05-2009, 02:10 PM
I imported a doorway I made in hammer editor as an object into XSI. I drew the doorway face with curve CVs, but now I need to extrude it back. All I have used is extruding a curve along another curve, so im not really sure what I need to do. This is what the doorway shape looks like (its just the inner face I am doing with CVs) then I am going to extrude it back, then scale it up a bit to make the entire doorway.

*Edit*

On a different note, 1 Hammer unit = 1 XSI grid unit. I am curious just so I can make sure my models exact, if theres anyway for me to specify for it to be like 256 grid units wide, or 512 grid units thick, or whatever.

http://imagenouch.com/images/2009/Feb/11233842896.PNG

Ohmanoggin
02-05-2009, 07:05 PM
You want Create / Polymesh / Curves to Mesh. An Extrusion Along Axis will work, but will not "cap" the ends. This command also allows you to round the corners of edges.

Scaling:
A trick I use for scaling is to make a cube 1,1,1. Then type in a scale that fits something your need. For example maybe the overall width of the doorway is 27.356 units. Make the cube that scale and then scale your object until it matches the cube width. Then freeze the scaling on the doorway object. Now anything you create will be the proper scale.

Hope this helps,
Ohmanoggin

CrimsonGT
02-05-2009, 10:11 PM
Oh awesome, that helped immensely. I sketched the inner line of the doorface with CVs, then dragged them away from the door and extruded them which gave me the exact shape I wanted. Got a couple questions pertaining to using it though.

1) It seems it will only work if the CVs are closed, when I left it open it did not convert it to polymesh, and when I closed it, it didnt look right (There shouldnt be a bottom on it, which closing the curve creates). The curve was still there on the back of the polymesh, and when I deleted it, the entire polymesh disappeared. Anyway to get rid of the curve without losing my new polymesh?

2) This is the main question that is really posing a problem. Basically I want to have the doorway model to look something like this

http://imagenouch.com/images/2009/Feb/11233871877.JPG

but when I duplicate the current mesh, and scale it out, it gets all wacky and I cant get it right. Is there any decent way to do this (to make sure its the right distance all the way around from the inner mesh). Im extremely anal about things being the right size, and lining up, and so on. I tried holding control, but theres never really a good median when using that, it instantly jumps up massively in size when using it to scale.

I assume once I have these two meshes, I can just merge them, then bridge the edges between them to close it off.

CrimsonGT
02-06-2009, 05:39 AM
I made a little video of my troubles if anyone cares to watch it and tell me what im doing wrong >.>

http://www.tf2rocketarena.com/extrudesucks.avi

Ohmanoggin
02-06-2009, 02:16 PM
I don't have the codec you are using to play the movie.

However, you can't use Curves to Mesh if your curve isn't closed, because it wants to cap and an unclosed curve can't be capped. If you want the curve open, then use extrude along axis.

After you create your polymesh hit Freeze (bottom right of screen). When you create an object from a curve, a relationship is setup so the object keeps updating as you change the curve. Freezing kills this relationship so you can delete the curve.

It sounds like you are trying to build a closed shape from pieces. Look at Create / Curve / Blend and also Merge. You'll also neede Modify / Curve / Close to close the last two end points.

Personally for cuves that are not freeform (especially anything mechanical looking), I recommend using a 2D sketching program like Adobe Flash or Illustrator.

Or better yet, you can get a free 2D CAD program called Solid Edge. They make a highend 3D CAD modeler, but give away their 2D sketching tools for free, which I find is very useful for artists. I recommend giving it a try if you are doing much architectual stuff and don't have a CAD product. Just google "Solid Edge" and you'll find the free 2D software. The program is pretty simple to use. You just draw circles and lines and the software seems to always know what you want. Trims everything pretty easy too.

Hopethis helps,
Ohmanoggin

bravmm
02-06-2009, 03:38 PM
What about switching from extruding curves to modeling it directly with creating a polygon and extruding that?
Just pick the viewport that shows the front of the object, press N to start off a new polygon, and draw the shape as you would with a curve.
After creating the polygon, extrude it to a solid block.

Or start of with a cube, and split, extrude parts of it to get the doorway. Shouldn't take more than 10 minutes to get it done. It's a symmetrical shape, so build half of it, duplicate, mirror and merge. Done. Or drawing half a polygon shape, or...

Just look outside the box you're trying to get it done now, reread the manual about curve extrusion, and try some other modeling methods as well. It will help you understand different ways of creating things. There's no best way, it's a mix of things.

Go find the thread on the free distribution of the 3DTutorial.com videos hosted by letterboxanimationstudios. It's all hosted on www.redi-vivus.com, they're offering tons of tutorials on XSI, there's stuff on modeling as well.

Good luck,

rob

3DRtist
07-05-2009, 08:50 PM
I don't have the codec you are using to play the movie.

However, you can't use Curves to Mesh if your curve isn't closed, because it wants to cap and an unclosed curve can't be capped. If you want the curve open, then use extrude along axis.

After you create your polymesh hit Freeze (bottom right of screen). When you create an object from a curve, a relationship is setup so the object keeps updating as you change the curve. Freezing kills this relationship so you can delete the curve.

It sounds like you are trying to build a closed shape from pieces. Look at Create / Curve / Blend and also Merge. You'll also neede Modify / Curve / Close to close the last two end points.


Hopethis helps,
Ohmanoggin

I'm trying just to extrude a circle along a spiral (neither are hand drawn). I choose the circle as the profile object and spiral as the guide object. (This is from the XSI Help). Then when I choose extrusion along curve, I get this error message "Cannont connect spiral to port group_1". I made sure that I only have those 2 curves selected and also select the profile object first.

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