Re: I Want An Easier, Faster, Better CAD Tool

Cliff wrote:
> 
> I'd sort of expect something like that as a NURBS curve or surface
> will map to an IGES file & IGES needs no kernels to be IGES. 
> And Rhino started out as a surface modeler, not a solids modeler 
> (which use kernels to produce BREP solids from such as NURBS 
> surfaces). You don't need a kernel to create curve or surface 
> either.
> 
> But what of the current Rhino solids "kernel"?
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I don't know what to think OpenNURBS is.  It appears, to me, to simply
be a library of functions that will read / write native Rhino 3dm.  A 
tool or hook for 3rd party developers?  I don't know.  The extent of 
my knowledge ends with what I posted.
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  "Rhino started out as a surface modeler, not a solids 
   modeler (which use kernels to produce BREP solids 
   from such as NURBS surfaces). You don't need a kernel 
   to create curve or surface either."

What is a "kernel"? 

Seriously. 
Is that wino bait?
Are we just playing with semantics?
It looks like a serious statement, with which I can't agree, so I'm
lacking some knowledge or the terms used mean something inconsistent 
with my understanding of them or the statement is incorrect. 

First: What is a "solid"?  
It's a concept, a database entity.

Unless something's changed since I last looked Rhino (v3) can create 
and manipulate nonmanifold boundary representations, it can boolean 
add or subtract two closed shells where there is an intersection.  It 
can calculate and re****t the volume represented. It can not create a 
"solid" with an internal void. It can create the closed shell 
representations.  It does not have a database structure to contain 
them, call it a "solid" and manipulate it as such; i.e. re****t the 
"solid" volume or boolean subtract its volume from an encompassing 
volume yielding two disjoint "solids".   

In my mind THAT is what makes Rhino a "surface", vs. "solid", modeler 
more so than its lack of all the typical Solid Modeler sequential 
function call macros that create surface geometry, perform intersect, 
trim, join operations consistent with the user defined boolean 
operator and validate the manifold solid b-rep object without 
additional user input.

To create a curve you need functions that accept two or more user 
defined points at minimum, possibly tangent direction, curvature and 
rate definitions and from that input return; usually, a graphic 
representation and coordinate values for any point on that curve.

To create a surface you need functions that extend curve creation, 
query and manipulation from one (U) dimension into the second (V) 
dimension.

To create a shell you need a database entity to contain one or more
surfaces, their sup****ting (curve) entities or pointers to discrete 
database entities that define them and any additional attributes that 
may be associated with the object, and you need functions that will 
manipulate the shell entity as a single object.

To create a solid you need a database entity to contain ... yadadada
.... and functions to manipulate the entity as a single object.      

So what is a kernel?
Parasolid, ACIS, Granite, ...
Is C(atia) A(pplication) A(rchitecture) a kernel?
Is Rhino's geometry engine, e.g. it's core creation, query, 
manipulation function library a kernel?
_ _ _ _ _ _

"But what of the current Rhino solids "kernel"?"

Obviously I can't answer that question.  

To the best of my knowledge, the extent of which was gleaned from
the previously mentioned and presumably lost forum discussions which 
McNeel tech and development personnel participated in; their geometry 
and database creation and manipulation functions are their own and 
were written 'in house'.    

If they have "solid" capabilities in addition to what I've described 
above I have no idea if they are 3rd party add-on, core product, 
licensed, owned, ...

I'd be tickled if I knew if they have a "kernel". 
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