9/6/2007
Morphic 3.0: The Future of the Graphic User
Interface
2. Coordinate Systems
2.1 Each morph has a Coordinate System
As I said before, each morph defines a coordinate system. The
appearance of the morph, as well as the location of the sub morphs
inside it are specified in this coordinate system. This means that if
the morph is moved, rotated or resized (actually "zoomed"), there is no
need to do any adjustment to the drawing logic or to the sub morphs:
The
drawing of the morph and its sub morphs will be done properly by the
rendering engine, as it does the conversion between coordinate systems.
Take a look at the map projections below: No matter which one you
chose, the latitude and longitude of your city are the same in all of
them.
2.2 Coordinate Systems are objects
There are many possible coordinate systems. Many of them are
non-linear. This means that drawing with them does a geometric
deformation on the object being drawn. These are some examples from Wikipedia:
(You can read more at http://en.wikipedia.org/wiki/Map_projection)
We should not be limited on which coordinate systems are possible.
Besides, for simplicity, coordinate system handling should not be a
responsibility for morph themselves. Therefore we need an expandable
hierarchy of CoordinateSystem objects. They specify a rule for
assigning
a pair of numbers, called coordinates, to each point in some space.
This
rule depends on the kind of coordinate system and its bounds, but it
also depends on where (and how) the coordinate system is located in
some
containing space. This Location information is not a defining property of the coordinate
system, as it could change anytime. A Location object specifies how a
morph (and its coordinate system) is located in some container morph
(and its coordinate system). A location includes a position (expressed
in the container coordinate system), an extent (also expressed in the
container coordinate system) and an angle of rotation.
Location information is external to the morph, and could perhaps
be stored elsewhere. I chose to store the Location in the morph because
it is the morph that controls it. This means that a morph may decide to
move around or rotate by itself.
All the numbers in Locations and CoordinateSystems are Floats, as they
are computer representations of real values.
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