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Co-ordinate Systems:
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Page 4
E-mail Billy.
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We have already discussed what a co-ordinate system
is, so now you need to be aware of the different co-ordinate systems and what
they do. The different co-ordinate systems are:
- View
- Screen
- World
- Parent
- Local
- Grid
- Pick
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View:
We have already touched on the View co-ordinate
system. It is relative to the whichever View is currently active. If you rotate
the object, the View co-ordinate
system remains unchanged. However, if you rotate the View, the
co-ordinate system rotates with it.
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Screen:
The Screen Co-ordinate System is very similar to
the View Co-ordinate System, except that when the
View is rotated, the Screen Co-ordinate system
remains unchanged.
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World:
The World co-ordinate system begins from a point in space called
the Origin. This is defined as x:0,y:0,z:0,
and represents the centre of our 3D universe. From this point, our 3 axis
extend as follows:
- x axis
Horizonal plane with increasingly positive values moving toward the
right.
- y axis Depth
plane, with increasingly positive values moving away from the front
view.
- z axis
Vertical plane with increasingly positive values moving up.
The
World Co-ordinate System is shown in
the bottom left hand corner of each view. You may have noticed that in
relation to the View Co-ordinate System,
the Y and Z axis have swapped. This can be confusing, but it's just
the way it is. The World Co-ordinate System is
unchanging, and is relative to nothing but it's own origin. The
World Co-ordinate System is used to calculate the position of
all objects in the scene. When
we describe things in relation to the World
Co-ordinate System, we refer to Absolute
Values.
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Parent:
This option uses the local co-ordinate system of the objects parent, as
defined by the hierarachy. This will be covered in a later chapter.
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Local:
A Local Co-ordinate System is generated for
every object when it is created, based on the View in which it is created. If
the object is rotated, the Local Co-ordinate System will
rotate with it.
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Grid:
This uses the axis of the active grid. User
grids can be created and positioned in the scene. We don't need to worry
about this option as we wont be using it.
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Pick:
This option allows you to pick and use the co-ordinate system of another
object. This is useful for moving an object along the surface of another object.
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The following exercise allows you to try out these co-ordinate systems. Don't
worry if you get confused, it will all make much more sense when you start using
Max more. Although it is possible to muddle through without really understanding
these concepts (I know I did!), I can't emphasise enough how much easier it all
becomes once you understand them.
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