On 9/22/06, Eric Maslowski <[EMAIL PROTECTED]> wrote:
These weren't general purpose scene graphs then, perhaps not scene graphs at all.
A scene graph is princply about uses a directed graph to "compose" a scene, both logically and spatially. It is an embodiement of the composite design pattern, where functionality is set up using "has a" relationships.
This is different from the approach above where entities are setup via "is a" relatioships.
In OO programming the "has a" is well know to be much more flexibility. However, with the flexibility that loose coupling brings the downside is that some operations require more work to obtain the effective state of subgraph.
Robert.
Thanks guys and thanks for the example, Don. With some of the past engines
I've worked on, an entity/node had access to everything that defines its
current state (xform, mat, etc.) and would just be derived from the
components that it needed.
class Door: public Animatable, public Drawable, public Entity {};
These weren't general purpose scene graphs then, perhaps not scene graphs at all.
A scene graph is princply about uses a directed graph to "compose" a scene, both logically and spatially. It is an embodiement of the composite design pattern, where functionality is set up using "has a" relationships.
This is different from the approach above where entities are setup via "is a" relatioships.
In OO programming the "has a" is well know to be much more flexibility. However, with the flexibility that loose coupling brings the downside is that some operations require more work to obtain the effective state of subgraph.
Robert.
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