Another angle: a kernel is a software module that takes instructions to
make
a solid model and outputs solid properties, derived geometric data, and
graphics data.
In Pro/E and other 3D parametric modelers, this means it takes the sketch
geometry for each feature (which is just coordinate values) and evaluates
it
into a set of surfaces. The resulting surfaces are evaluated to ensure
they
all match up along edges to form a valid solid. (Solid models are really
just surface models with extra restrictions). From this surface
representation the kernel can translate into other formats, output
graphical
data for the OpenGL display, calculate mass properties and measurements,
etc. Anytime that basic geometry is added or changed, the kernel
regenerates the model to keep it up-to-date.
Older non-parametric kernels do the same thing, except they aren't
designed
to efficiently repeat and re-create the generation process. For example,
the V12 AutoCAD 3D kernel (AME) did not allow you to edit definition of
the
solid, but each time you made a change (e.g. a hole) it calculated
everything again. It was really slow. In v13, AutoCAD switched to ACIS,
and ACIS calculated the new shape directly from the existing shape. Much
faster, but still not parametric. In Mechanical Desktop they finally got
parametric, using ACIS again I think.
When a company sells the use of their kernel, it allows another developer
to
work only on interface issues and interactivity issues. Also, it makes
applications based on the same kernel interface better.
Dave
"yogesh" <ypjofficial@[EMAIL PROTECTED]
> wrote in message
news:f88a27e4.0307290744.137c0fa2@[EMAIL PROTECTED]
> hi all,
> and sorry to interrupt you like this.!!!
> actually i have lot of doubts and lot of confusion about the role of
> solid modeling kernel inside a solid modeler.
> i am cad cam student and worked on packages like solidworks, ideas and
> cadmax.
> and also i have a little bit of programming background(half knowledge
> is dangerous indeed!!!) and that's why this confusion.
> could someone please tell me what is the exact role of a kernel??(i
> also heard of an operating system kernel)
> and what is the difference between apis like java3d, opengl and
> kernels like parasolid and acis?? or is opengl also a kernel???
> also if possible i want to see some sample kernel code..where can i
> get it from...
> i will be very grateful to you if you manage to clear my confusion and
> doubts..
> and also i am interested in knowing the history about the kernel
> phenomenon..how come it started..which was the first kernel
> developed..etc ..
> thank you and have a nice day....
> regards,
> yogesh
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