[Bf-python] Geometry Data

[McCracken, Andrew]

This sounds like a good idea.

There are many c/++ libraries out there for geometry, none of which I am familiar with.

www.cgal.org looks pretty awesome. Maybe too huge tho.

Would it be a better idea to choose a particular library to wrap, and distribute it as a recommended extension to the blender python api?



-----Original Message-----
From: bf-python-bounces at projects.blender.org on behalf of Gilbert, Joseph T.
Sent: Tue 8/1/2006 2:18 AM
To: cbarton at metavr.com; Blender Foundation Python list
Subject: RE: [Bf-python] Geometry Data
 
This should be divided into more logical groupings.
Geometry should be split into Line, polygon, etc. with associated
methods. 

A Polygon object would be more appropriate I think then a VectorArray in
the Geometry module. Also a Line object, etc. for testing intersections.
Calculating bounds is only useful on something with a volume....

-----Original Message-----
From: bf-python-bounces at projects.blender.org
[mailto:bf-python-bounces at projects.blender.org] On Behalf Of Campbell
Barton
Sent: Sunday, July 30, 2006 9:47 PM
To: Blender Foundation Python list
Subject: [Bf-python] Geometry Data

Hi Guys,

Iv been thinking about having more abstract geometry data types.

I posted this before but here are some more details,

First, Id like to impliment a vector array type - basicly an iterator 
that provides wrapped vector access to a C array. it would have the same

malloc problems ans Mesh but youd just need to define the size to begin 
with.

once you had this data you could operate on it as a blob, apart from 
being faster it would be easier to read and reuire a lot less looping in

python.

va= Geometry.VectorArray(200, 3) # 3d vec init as (0,0,0) 200 items

or it could be initialized from a a list of vectors

va=Geometry.VectorArray(me.verts)

now you could transform it just like a mesh
va.transform(matrix)

or get the bounds (annoying to do in Python)

bounds=va.bounds() # possibly have a function to intersect bounds also

Other functions could be

.removeDoubles() # remove points
.convexHull() # return indicies
.nearest(someVec) # finds the closest point to a vector
if Vector in VectorArray  #  would search for the point in the array.

It could also be  used to define a poly line 2d or 3d

va_poly2d.area() #area of the poly
va_poly2d.PolyPoint(pt) #is the point inside the 2d poly
va_poly2d.PolySelfIntersec(pt) # does the poly intersect its self
va_poly2d.PolyIntersectPoly(poly2d)
and of course the existing poly fill ;)


I think this could also save memory too- how much memory does a BPy 
vector take up by its self?

Theeth, respect your opinion (that this isnt a bottlenack) but Id like 
to prove myself wrong before assuming these functions would not be much 
faster in C /python
also depends on the scripts you write I suppose.

I could make some tests and use a Mesh  as an example of a python array 
(pretend of course) - then compare with a list of vectors.

Maybe we should look an numarray first?
Pygame had some examples of pixel operations in in numarray - Realtime 
image distortion, that you could no way do in Python, so I think there 
may be a use for this.

-- 
Campbell J Barton

133 Hope Street
Geelong West, Victoria 3218 Australia

URL:    http://www.metavr.com
e-mail: cbarton at metavr.com
phone: AU (03) 5229 0241
_______________________________________________
Bf-python mailing list
Bf-python at projects.blender.org
http://projects.blender.org/mailman/listinfo/bf-python
_______________________________________________
Bf-python mailing list
Bf-python at projects.blender.org
http://projects.blender.org/mailman/listinfo/bf-python



-------------- next part --------------
A non-text attachment was scrubbed...
Name: winmail.dat
Type: application/ms-tnef
Size: 4506 bytes
Desc: not available
URL: <http://lists.blender.org/pipermail/bf-python/attachments/20060801/434156a2/attachment.bin>