Is there something like Geometry- and Attachment constraint??

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  10 October 2009
Originally Posted by vauric: Am I doing something wrong here? The non blended geometry constaint script works fine.

I should have made it clearer in the video. Sorry about that. Anyways, Here's how to do it...

Select the object to be constrained, click the menu item, left mouse click on the constraining surface, then middle mouse click on the constraining object.

It should work then. PM me if you're still having problems.
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  10 October 2009
Ah great, works fine. I should have noticed at the bottom of the screen, that middle click was needed.

Thanks for the clarification.
 
  10 October 2009
Mohammad, this is wonderful! Thank you so much for doing this! If you ever find yourself in the mood to take it a step further, any chance we could get the option to instance the to-be-constrained object so we can scatter them across the surface? (I'm assuming this would require the use of Softimage "models.") I'm thinking either random placement, like we'd see in a forest of trees, or uniform placement as we'd see by constraining rivets to a curve. (If we could constrain to a mesh's edge, and have those objects move accordingly when sub-divided, I'd fall over with happiness!)

If you can do all this, you could release it as Softimage 2010 SP1 as far as I'm concerned.
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  10 October 2009
Originally Posted by SFDD: Mohammad, this is wonderful! Thank you so much for doing this! If you ever find yourself in the mood to take it a step further, any chance we could get the option to instance the to-be-constrained object so we can scatter them across the surface? (I'm assuming this would require the use of Softimage "models.") I'm thinking either random placement, like we'd see in a forest of trees, or uniform placement as we'd see by constraining rivets to a curve. (If we could constrain to a mesh's edge, and have those objects move accordingly when sub-divided, I'd fall over with happiness!)

Thanks David

I did a quick little test to make sure, and yes, it is possible to use this constraint on a cloned object. And since cloned objects have their own kinematic state, they can move independently of the original.

So in principal, it can be done, but I'm not too sure about the specifics of your request. Would you mind elaborating a bit?
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  10 October 2009
Originally Posted by ShaderOp: Thanks David

I did a quick little test to make sure, and yes, it is possible to use this constraint on a cloned object. And since cloned objects have their own kinematic state, they can move independently of the original.

So in principal, it can be done, but I'm not too sure about the specifics of your request. Would you mind elaborating a bit?


Here's the workflow I was thinking about:

Say, for example, you have an airplane fuselage and you want to put some rivets along the various section seams. It would be great to be able to select one of the edges as a path, then invoke your tool, select a rivet model and have your tool create instances of that along the edge. Options would include total number divided evenly, number per point span, or something like that.

The second with was to be able to do the same thing on a surface. In that case, you'd select the surface, invoke your tool, choose the model and then choose setting with regard to number of instances and placement randomization. Say, for example, 0% randomization places the instances in a perfect array, whereas 100% places them totally randomly. (Of course no two instances would ever be placed at the same point.)

Does that make more sense?
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  10 October 2009
Originally Posted by SFDD: Here's the workflow I was thinking about:
.
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Does that make more sense?

It does make a lot of sense actually.

I think I have an idea. It's not exactly what you want, but it would probably be more general, and hopefully more useful. I'll see if I can run a few tests this weekend.
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  10 October 2009
I have a feeling that something very usefull will come from this.

Thanks again ShaderOp...for all your effort.
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  10 October 2009
Originally Posted by SFDD: Here's the workflow I was thinking about:

Say, for example, you have an airplane fuselage and you want to put some rivets along the various section seams. It would be great to be able to select one of the edges as a path, then invoke your tool, select a rivet model and have your tool create instances of that along the edge. Options would include total number divided evenly, number per point span, or something like that.

The second with was to be able to do the same thing on a surface. In that case, you'd select the surface, invoke your tool, choose the model and then choose setting with regard to number of instances and placement randomization. Say, for example, 0% randomization places the instances in a perfect array, whereas 100% places them totally randomly. (Of course no two instances would ever be placed at the same point.)

Does that make more sense?

That's exactly the kind of stuff that ICE does really well at And would be a lot leaner than generating a ton of geometry or N instances instead of a single point cloud of size N.
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  10 October 2009
Quote: Say, for example, you have an airplane fuselage and you want to put some rivets along the various section seams. It would be great to be able to select one of the edges as a path, then invoke your tool, select a rivet model and have your tool create instances of that along the edge. Options would include total number divided evenly, number per point span, or something like that.


An offset value would be good also.

That is my number one issue...how to have the best of Nurbs, Solids and Polygons(SubD's) modeling in one place.
In several CAD packages it is possible to use a line to do that easily , even with History and follow any later change in surface topology.
 
  10 October 2009
Originally Posted by Werner: I have a feeling that something very usefull will come from this.

Thanks again ShaderOp...for all your effort.

Don't thank me yet. I already have one failed idea under my belt

Anyways, the idea I had in mind was trying to find a way to constrain an object to a mesh, but use the UV coordinates of the mesh to control the constrained object's position. Sort of like the built-in surface constraint, but for polygonal meshes.

To better illustrate my point, here's what can already be done with the built-in surface constraint:

http://vimeo.com/6930811

If the same thing can be done with polygonal meshes, then it would be a lot more flexible, since a polygon mesh can have multiple UV maps and you can lay them out however you please.

So if this hypothetical constraint existed, you would need to specify the constraining geometry and the UV map, and then just animate or position objects by changing the UV coordinates on the constraint.

That's the idea I had in mind, but it's not easy to implement. Biggest issue is mapping a point on the UV map to the corresponding position on the mesh's surface. There's away to obtain the UV coordinates from the XYZ coordinates on a surface (sort of at least), but not the other way around. At least none that I could find in the SDK.

Thoughts? Ideas?
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  10 October 2009
I have no thoughts on how to achieve that, but if you can pull it off you'll be my hero of 2009.
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  10 October 2009
I think an issue could be that it's not a 1-to-1 relationship between uv and xyz .
an xyz coordinate maps to only one uv coordinate per uv set, but not the other way around.

Then again, you could just pick the first xyz the inverse lookup finds, assuming the uv has been built in a way anyway that no multiple xyzs are intended

The inv. lookup will be surely tricky to write though, especially when it comes to subdivs!

ps- ShaderOp I hope U don't mind I added your addons to my resource listing website rray.de/xsi. Let me know and I'll remove them right away!
ps I' ve just read about curvature in your post, this reminded me some curvature related stuff can be found here too rray.de/xsi

ray
 
  10 October 2009
Originally Posted by ray: ShaderOp I hope U don't mind I added your addons to my resource listing website rray.de/xsi. Let me know and I'll remove them right away!

Of course I don't mind! If anything, I'm grateful for all the work you're doing to keep that list up to date.
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  10 October 2009
Originally Posted by ShaderOp: So if this hypothetical constraint existed, you would need to specify the constraining geometry and the UV map, and then just animate or position objects by changing the UV coordinates on the constraint.


Wouldn't this approach limit the "randomness" to only where a UV existed? It seems to me that unless the mesh was extremely dense, it might be pretty easy to spot the UV pattern. Imagine a grid of 8 by 8. If you then applied some rivets to that based on the UV map, would they end up scattered along the UV lines only?
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  10 October 2009
Originally Posted by SFDD: Wouldn't this approach limit the "randomness" to only where a UV existed? It seems to me that unless the mesh was extremely dense, it might be pretty easy to spot the UV pattern. Imagine a grid of 8 by 8. If you then applied some rivets to that based on the UV map, would they end up scattered along the UV lines only?

No, that shouldn't be an issue. At least it wouldn't be if things work out.

The only feature I will not attempt to touch is having it work with live subdivided surfaces. The workaround would be the same one suggested with the geometry constraint plug-on, and that is to apply the "mesh subdivide with center" operator to the mesh, and then use the resulting object as the constraining mesh. I hope that would be a reasonable compromise.
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