Coordinate system.

[SheepFactory]

well global is always aligned to the world axis. which means y is always pointing up. Local on the other hand depends on the normal of the surface.

example:

extrude one face of a cube and rotate it. Now select the extrude tool again , you'll see it rotated itself to match the normal's direction. If you click on the blue circle it'll switch to global mode and you'll see the difference.

hope this helps.

Ali

[Peace455]

I get it.


So nomal the axies would be based on the direction of the selected faces let say. and World would be the world set opf Axies (the X,Y,Z) that is in the bottom left of the perspective viewport.

then what is "Object" and "Local"? Local is selected by default so when I move objects around its on local mode.

the Help says

Object:

"Moves an object in object space coordinate system. Axis orientation includes rotations on the object itself. If several objects are selected, each object moves the same amount relative to its own object space coordinate system."

I opened Maya, created a bunch of poly primitives, and one of the objects, I rotated the local rotation axis . . .. ohh its call LOCAL rotation axis . . :D its just clicked there. So its based on rotation not translation, I get it now, I see what object is now. but

Local

"Aligns the object to the rotation of the parent object. Movement is constrained to those axes in the local space coordinate system. The object is aligned to the rotation of the parent object and does not include the rotations on the object itself. If several objects are selected, each object moves the same amount qrelative to its own object space coordinate system."

I kinda get local but I'm missing it, I don't feel as though Ive fully grasped it, so is local based on parented objects?


thanks for the help

Peace
M.:D

[playmesumch00ns]

Yep you're right, local is based on parenting.

The way Maya (or any other 3d software) represents objects, is with a list of vertices in object space. This is just saying that the object is defined about the origin. Now if you move the object or rotate it around, it's vertices will move in world space but still stay the same in object space, otherwise the object would have changed shape! So the vertices are still defined around 'their own' origin -- the object's pivot -- and are just transformed back into world space when they need to be drawn. (well technically, the GL is transformed into object co-ordinates, but this means exactly the same thing and is not worth worrying about).

So you've got a co-ordinate system for each object. As I'm sure you're aware you arrange objects in a heirachy. This just means stacking their co-ordinate transforms. The 'world', 'object' and 'local' tool modifiers just correspond to which co-ordinate system your points are transformed into before the move, scale or rotate is applied, and then the points are transformed back. For example you might have this arrangement in the outliner:

->WORLD
.......|
........--->OBJECT1
..................|
..................--->OBJECT2

So if you do a 'world' transformation on Object2, Maya transforms the points of your object into world space, does the transform, and then transforms them back. If You do a 'local', Maya transforms the points into the co-ordinate system of whatever's one level up the heirachy (in this case Object1), then transforms back. If you do 'object', then no co-ordinate system transformations are required, and Maya just does the move, scale or rotate on the points in Object2's co-ordinate system.


Sorry if any of this is patronising, just thought it might help your understanding:thumbsup:

[CGTalk Moderation]

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.