[Gdal-dev] OT: Shapefile's multipatch

Frank Warmerdam warmerdam at pobox.com
Sun Oct 29 11:34:41 EST 2006

Paul Selormey wrote:
> Please I need help in understand some aspect of the multipatch format
> of the shapefile.
> In particular, I want understand some points on
> 0. triangle strip
> 1. triangle fan
> The question is: Does the "NumParts" includes the number of triangles
> in the strip or fan? (my own understand is that it does NOT, but wish
> to confirm, just in case!).


 From reading the specification it seems the NumParts does not
address the number of triangles in a strip or fan.  Rather it
indicates the number of parts, each part potentially being a
triangle strip, triangle fan, outer ring, inner ring, first
ring or plain ring.

I don't actually have much first hand experience with multipatch
data.  When I have encountered it I think it was typical for each
shape to be a single part, either a triangle strip or a triangle
fan.  But I don't recall details.

If you have a couple not too large, but "real world" multipatch
examples that are redistributable, I'd love to have a copy.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org

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