Monday, May 2, 2005, 18:56:01, Stefan Gerlach wrote:
> Hi,
> Is it possible to change the range of a surface plot without changing the data
> every time?
No (but see below). Some early version of qwtplot3d implemented a set of
cutting planes. The problem was, that people tend to have very different
requirements (more than one cutting plane per coordinate, non-planar
cuttings etc.). For the very same reason (in principle wishable)
incremental updates are not supported straightforwardly. As soon as data
have been loaded, the model becomes more or less static. This has some
advantages regarding OpenGL optimization (e.g. you couldn't do more or
less real time movements also with relatively large data sets).
So, I outsourced the responsibility to the user to prepare the data
sets in a suiting way.
Nevertheless I see your point and it is also one reason for not giving
public access to the libraries internal data structures. This way I'm
able to claim the ground for other implementations in the future (to
mention - not for the next versions).
Anyway, it might be possible to mimick the behavior of your problem with
Enrichments in implementing the usage of OpenGL clipping planes in
Enrichment::drawBegin() (setting the plane(s)) and Enrichment::drawEnd()
(removing). It should be efficient, because it can utilize hardware
clipping.
I still had to give them a try in code to be sure, though.
Micha
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