I am pretty big on Geometry and Math. My questions for this posting are largely hypothtical.

To what extent can I control where a point is placed. I mean to say that some of the objects I want to create will need to have exact control of where i place my points. Of course, You always know where a point will be placed, but I don't want to import some object from another software which uses all kinds of parametric modelling to create a rather abstract shape. Would it be easier to do that than to right some intense formulas for point creation within actionscript? I would like to be able to do object modeling such as offsetting planes, placing lines at intersections of planes, and the3 same for points. Can I use graphing formulas to calculate intersections in actionscript?

That leads me to my next question. Is there any way to move a reference point to a given location my world orientation instead of position from the center of the object. Also, is the center referred to as 'center' actually at the object center or the center of the bouding box. That can be a huge difference. I suppose I could request the position of the point so that I can move it a certain distance, but I want to simply move a point or reference point using the world coordinate system instead of local. How can that be achieved?

I plan to create objects in loops while changing the positon and rotation of the object based on grouping them and following the same pattern all the way up a heirarchy structure to the top level. Should i then be able to control each subgroup in turn by using the Dot Notation from the top level all the way down to the Object3D itself? My aim here is to be able to manipulate an object to the degree of a skeleton system, but I will not be using it for this purpose.

Thank you for any help or inspiration you can give me.

If I want to move something, I wrap it in a translation tranform, then set the position of the translation transform.

Petit's tutorials show how to do this in Sandy 1.1.

I'm using Sandy 1.2. It may differ in other versions, but I think 1.1 and 1.2 are the same in this regard. I don't know about Sandy 3.0.

You can do anything you want that is possible in actionscript. You may have to extend the core, but you havent listed anything that requires that yet.

For instance, manipulation of points on a plane? Check this out!

http://www.onlinekarma.net/flash3d/index.p...&id=16&Itemid=1

See the examples.

I hope this answers your question. If not bounce back and I or someone will clarify.

I do have some questions about the point reference. If I understand it so far, you can only move this from object center using locl coordinates? You cannot use the world coordinates at all?

So, what is considered object center? Is the absolute center mass considered the center or is it the center of the bounding box?

Is it possible to connect the point of reference to a vertex by name, effectively moving the reference point in a free form object? Would you have to actually write formulas to calculate the offset of the center to you reference vertex so you can move the reference point?

After all that is figured, can I group and move, group and move, group and move? I mean here to building something of a hierarchy and transform the groups, not the objects. Can I do that ,too?

I just thought of another type of question. Can you animate the vertex points of an object in real time?

I'm not sure if this is what you're asking, but....

Yes, you can group two objects together by making them children of a transform group. Then any transform you apply, such as a translation, causes both objects to move in unison. I imagine you could do this in a hierarchy, but I haven't tried it.

thank you for your input!

what do you know about the reference point question or animating the vertex points?

Each object has a different "center", known as its registration point, which is not the geometric center. For pyramids, I think it is the bottom. For other objects such as spheres, I think it is the center.

You can move an object in the world using a Transform Group to translate it in space.


See Petit's excellent tutorials for more info.

I knew that the pyramid had a reference point in the the center base. I modified the primitive to build part of my model (wedge unit).



I know about the object translations. My interest lies more with the registraion point. Since the center base of a pyramid is neither center mass or center of the bounding box, is the registration point specified? When I modify a Pyramid primitive, can I place the registration point at the tip. Will that point always be at origin? Doesn't that conflict with saying that the reference point is center object by default?

I only want to be able to place my reference point where I want to, no matter what the shape I make. I also want to be able to move the reference point of groups, but I am still unclear as to which center you mean for reference point defaults.

I think I can add this centerPoint property at the primitive generation!
That my be a nice new feature.

going to check that, and hopefully implement it quite soon

++

If I understand correctly, it should be the registration point property, not the center point.

Of course, the registration point might default to the center point, but if the registration point is settable, it should be called regPoint, not centerPoint. Of course, you might want both properties in cases where they differ.


The center point would be read-only, based on the geometry.

The registration point would default to the center point (or some other logical choice, depending on the object) but be read/write.


For example, for text fields in Flash, I think the reg point is the upper left, but for movie clips, I think it is the center.

Bruce

Yes Bruce, I meant that.
To be able to change the center of rotation of the shape to clarify. As you clarified this, I would name it the registration Point, unless there's a more appropriate name english that that I don't know hat fits better.

So, is this a feature now, in verison 1.2? Text feilds and MovieClips have registration points. I believe I know what you mean. When I create a button in Flash, I can set where I want that point to be for placement. How does that work with Sandy and 3D. Is there a 3D registration point that I can use for this effect, and I do know that the center point is fixed. My questions about that are related to the where the center is located. Is it center mass or center of the bounding box of an object? The two of those can be quite different. Thanks for any help.

Well the center point if generally the mathematical one. I must say that when I created primitive with symetry I choosed the center (you can consider this as center of bounding box), but for those that are not symetric, the center isn't very clearly positioned. Simply because I don't have the feeling that there's a better place than another.

If I introduce the registration position thing, it would allow to change it in order to fit your needs! That's the good point.


I'll do that for 3.0 and 2.0 versions, still in development, but it would be easy to port back, if somebody wants to.

Best,
Thomas

Currently, version 1.2, where is the center point placed? From what you mentioned, the center point is defualted to the center of the bounding box and is considered fixed. It's the registration point that is movable. So, would that actually be the reference point or are the different as well? Where do I specify the registration point? If the reference point is linked to the center point, can I move it to the registration point by name reference so that I will know where it is exactly to move it where I want? Is that too confusing?

Well you can't change it easily, that's why I would like to add this feature.

For the moment, you'll need to apply a transation to the object. The traslation can be interpreted as a registration modfication if you use it correctly.

Thomas

I believe you can also set the axis of rotation, which effectively changes the center point about which an object is rotated