Re: Core Data vector modeling query
Re: Core Data vector modeling query
- Subject: Re: Core Data vector modeling query
- From: Paul Tomlin <email@hidden>
- Date: Mon, 1 Dec 2008 17:30:33 +0200
Thanks Erik,
On 01 Dec 2008, at 4:59 PM, Erik Buck wrote:
Vector3DReference is abstract. I have derived Vector3DReference for
all of the cases where I have other entities with relationships to
Vector3DReference. For example, I have a Billboard entity that has
a "to one" relationship to BillboardAnchorVector3DReference which
has a reciprocal "to one" relationship back to Billboard.
As I understand it, your model is equivalent to the example I gave of
using distinct entity types for each 'endpoint' (as I described it).
I'm still pondering if that's going to work for me, I suspect I should
just try it and see what becomes a problem.
That old adage "every problem in computer science can be solved with
another layer of indirection" comes to mind.
It is common in 3D systems to have a large collection or database of
points/vectors and then reference the points/vectors for index or
ID. E.g. consider multiple triangles that all share a vertex. When
the vertex changes, all of the triangles that share the vertex are
updated. Sharing vertex data also reduces the storage required vs.
lots of copies of the vertex.
Thomas Davie wrote:
It's most common for 3D apps to pack the vertecies into arrays, and
then create index arrays that index into the vertex/normal/tex coord
arrays to get at the data. These can then be uploaded so that all
the lookups etc happen on the graphics card, and no data need be
fetched from system memory when you try to draw.
You should look at glVertexArray and related functions.
I seem to have completely made a muck up of using an analogy. I'm not
dealing with 3D data at all, though I can see the similarities between
that and my domain. Vector may have been then wrong term to use, I'm
really dealing with a directional, anchored-at-both-ends, link between
two entities.
Thanks for the help guys.
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