Dear Brian, dear mesa3d-team,

attached is the promised example to reproduce the slow execution of
trimmed NURBS with mesa7.03.

I actually used and modified "trim.c".
Either changing the u-knot-vector ("trim_slow.c") or the
v-knot-vector ("trim_slow_2.c") to a larger number range is causing
the decribed slow execution/ slow display.

The example "trim_test.c" has both the knot-vectors u and v set to
larger values, and then the execution is (almost ?) as fast is the
original "trim.c".
I think: almost (hard to notice). But it may be worth too, to take
a look at it.

After doing some other work, I may look at the reason of the above
mentioned slow execution in mesa 7.03.
Let's say; starting in about two weeks.

Comments and questions are welcome,
- Ruediger.


ruediger janecke wrote 05/03/2008 04:15 PM:
Dear Brian, dear mesa3d-team,

as promised, I did some more testing with the example
of a trimmed NURBS surface (half sphere - rational b-spline),
that was executed/ displayed very slow - a lot of paging was
going on.

The reason seems to be:
  the parameterization of u and v of the surface (to be trimmed)
  has to be in a "close" number range.

In my example
the parameterization of u is in the range from  0.0 to 400.
while in v, it is in the range fromm 0.0 to 3.14  .

I changed the parameterization and my example was executed/
displayed as fast as "trim.c" from the "red book".

I think, this a good news to get an idea about a fix in
mesa3d, but also to be able to adapt the application to that
matter in the meantime.

I will come up with the examples showing the difference next
week.

Have a good weekend,
- Ruediger


Attachment: trim_slow.tar
Description: Unix tar archive

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