Modifying The Origin Of A Model

[Springheel]

Anyone know how to do this in Lightwave? The model's origin determines how it will rotate (and I think comes into play in physics collisions as well) but some of our models have origins that are outside of the model itself. Ish mentioned recently that some crates need to be changed, and I know the weapons do too.

 

But moving the origin isn't in the (very) small list of things I know how to do with LW. Is it something that's fairly easy to do? Dram, have they got to this in your course yet?

[sparhawk]

In Blender you switch to vertex mode and then select all vertices. When you move them the origin of the model stays the same, because this is a property of the model as a whole. You can try and see if this also works in LW like that.

[Springheel]

So you reposition the model, not the origin? I could try that, though at the moment I don't know how to even SEE the origin in LW (like I said, very small list of things I know how to do).

 

Another question while we're on the subject--should the origin be directly in the center of the object? That would seem to make sense for rotation, but I thought a mapper posted that the origin also determines how easy it is to make objects sit properly on the grid, so there may be more to it.

[Ishtvan]

I think there's also a "model_offset" key that will let you just edit the def of the item and move the model relative to the origin, but that would be a pain in the ass trial & error thing.

[OrbWeaver]

So you reposition the model, not the origin? I could try that, though at the moment I don't know how to even SEE the origin in LW (like I said, very small list of things I know how to do).

 

You can do either in Blender, so I presume you can do either in LW. Having no experience with the latter I cannot advise how to do this, but it is a common enough operation so should be documented somewhere.

 

Another question while we're on the subject--should the origin be directly in the center of the object? That would seem to make sense for rotation, but I thought a mapper posted that the origin also determines how easy it is to make objects sit properly on the grid, so there may be more to it.

 

Yes, it is the origin of the object that is "snapped", so it should always be positioned such that when the origin is snapped the edges and faces are in an appropriate position (e.g. on another gridline).

[sparhawk]

The origin of on object should be wherever it makes most sense for that particular object. Regarding the movement of the origin in Blender. I think there is not special key for this or it was added later after I asked about this. Since this seem to be quite a common function I can imagine that it works the same in most other 3D apps.

[Springheel]

Yes, it is the origin of the object that is "snapped", so it should always be positioned such that when the origin is snapped the edges and faces are in an appropriate position (e.g. on another gridline).

 

Sorry, I have no idea what that means. Snapped?

 

The origin of on object should be wherever it makes most sense for that particular object.

 

That's only helpful if you know what the origin actually does.

[oDDity]

THe origin doens't do much for most models, but for somehting like a door, you want the edge where the hinges go to be in line with vertical axis on the grid, not have it in the middle. For a bucket, it would be better to have the origin line up with the base at the edge, at the fulcrum point where it tips over. It makes it easy to rotate in the editor, if the origin was in the middle of the bucket, you'd have to rotate and move it in turns to try and have it perfectly tipped over on it's side.

So basically, if a model has an obvious fulcrum point, have the origin there, or lined up with it. THe origin in lightwave becomes the rotational fulcrum in the editor.

[sparhawk]

The origin determines where the object rotates around and where it's position will be. So for objects like a bucket, as Oddity said, the origin is best at the base, because if you put the bucket down and the origin is somehwere else, you need an offest to align it with the floor. For a ball it is obviously in the center. For a book or door it would be at the hinge and for furnitures it would also be at the base most of the time.

Just try to think about how to tip the object over. From this you should be able to determine a good centerpoint.

[Dram]

Actually we're starting LW in two weeks lol.

 

As for origin moving, you have to move the model, as was said.

[OrbWeaver]

I think there is not special key for this or it was added later after I asked about this.

 

Select the object. Position the 3D cursor with left-mouse where you want the origin to be. Hit F9 to show the Editing buttons and click the Center Cursor button in the Mesh panel.

[Springheel]

Ok, I think I understand where the origin should go...now how do I modify it in LW? So far I can't even FIND it, let alone move it.

[Solis]

If you're just modifying the LWO object in the modeler, I believe simply move the model so that the place you want to be the origin is at the 0-0-0 coordinates along the X, Y, and Z axis. Although I've only used Lightwave up to version 5.6 mostly, so it might be different in your version (although I think they kept the same layout the same). You should just need to line up the model so that the origin is in the center of the larger lines in each viewpoint.

[Domarius]

Yeah that's usually the case - look for world position 0,0,0 in the 3D views - that's probably your origin. (Usually the very center of the grid on the floor) Select the entire model and move it till position 0,0,0 is where you want the center to be.

[sparhawk]

If you can enter numbers you should do that instead of moving it. if you have tiny fractions off in the position this can cause troubles when the model is repeatedly rotated or handled. Normally an 3D app has a way to enter exakt numbers, so use these instead. Then you can also be sure that you really have the positioning and angling that you want it.

 

You also may have to bake the new position. At least in Blender this is required and it may be needed in other apps as well. What this mean is, that you reset the vertices such, that they new positioning is now the default 0,0,0 position.

As an example: If you create an object at 1,0,0 and move it to 0,0,0 then of course your object is positioned at 0,0,0 at the moment, but the origin is now at -1,0,0. In this case you must tell the app that this new position is indeed now the default position, so that it really is a 0,0,0 when you position it at 0,0,0. Hope I exlpained this in an understandable way.

[Domarius]

That's true. In 3DS Max you have to go to the heirachy tab and click "Freeze position" (can't remember exactly).

 

Basically all your movements, and resize operations, are all relative to the original mesh. They are applied on top of it - the actual vertex positions aren't modified - they are, but only when rendered. The way they're stored is the same way as when it was created. I am assuming this is because of the innacuracies since the positions aren't infinetly precise, if you kept rotating and resizing the actual vertices, the mesh would slowly go out of shape.

[sparhawk]

Yeah. "Freeze" was the term. Baking applies to the textures.

[ascottk]

For Lightwave 9, at least, you move the origin by actually moving the model so if you want the origin to be in the center, move the model to the world(?) center. That's one way of doing it.

[oDDity]

That's what everyone has already said.

WHy resurrect a month old thread to repeat that.