2004-march.txt

acis说明文档

api_sweep_with_options(pface,path_dir,swOpt,m_pAcisShape);


							ENTITY *sweep_result
= NULL;
							if(m_pAcisShape)
							{
								sweep_result
= m_pAcisShape;
							}
							else
							{
	
check_outcome( api_get_owner(pface,sweep_result));
							}

}
                        pface = pface->next_in_list();

					}while (pface);
                    ps = ps->next();

				} while(ps);
                pl = pl->next();
			}while (pl);
		}
	}



thank you very much for your help,



Juergen
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From nfarnsworth at web.de  Thu Mar  4 10:44:07 2004
From: nfarnsworth at web.de ([e-mail])
Date: Thu Mar  4 04:46:19 2004
Subject: [Acis-alliance] creating relative coordinate systems
Message-ID: <[e-mail]>

Hello,

I want to create two cuboids in each case relative to a WCS. I do this in the following
source code:

BODY* block1 =NULL;
BODY* block2 =NULL;
outcome result; 
SPAtransf wscT = translate_transf(SPAvector(10.0,0.0,0.0));
WCS* wcs1 = NULL;
wcs1 = ACIS_NEW WCS(wscT);
result = api_wcs_set_active(wcs1);
process(result);
//create a block which is relative to wcs1
result = api_solid_block(SPAposition(0.0,0.0,0.0),SPAposition(10.0,10.0,10.0), block1);
process(result); 



WCS* wcs2 = NULL;
result = api_wcs_create(SPAposition(25.0,0.0,0.0),SPAposition(1.0,0.0,0.0),SPAposition(0.0,1.0,0.0),wcs2); 
api_wcs_set_active(wcs2);
process(result);
//create a Block which is relative to wcs2
result = api_solid_block(SPAposition(0.0,0.0,0.0),SPAposition(10.0,10.0,10.0), block2);
process(result);


//unite the two bodies to one body
result = api_unite(block1,block2);
process(result);


To examine the result block2 I store it in a file and view the file in an ACIS Viewer.

ENTITY_LIST list;
list.add(block2);
FileInfo info;
info.set_product_id("ABC Application");
info.set_units(1.0);
result = api_set_file_info(FileId, info);
result = api_set_file_info(FileUnits, info);
process(result);
FILE* pf;
pf = fopen("..\\output.sat","w");
result = api_save_entity_list(pf,TRUE,list);
process(result);
fclose(pf);

But the result is not as I expect because there is only one cuboid and it should be two cuboid with a distance of 10 points in x-direction.  The problem is, that the relative positoin to the wcs is disregarded.

Could you tell me  what the mistake in the source code is and how I can create bodies relative to a WCS?  Is it posible to modify a body which is relative to a wcs but disregard the absolute position.

Thanks for your support
Niklas
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From zz_zxc123 at cims.sjtu.edu.cn  Sun Mar  7 14:59:13 2004
From: zz_zxc123 at cims.sjtu.edu.cn (zhang xuechang)
Date: Sun Mar  7 01:56:37 2004
Subject: [Acis-alliance] 
	help: How to use the function:  HA_Compute_Entity_Pointer(key,
	FACE_TYPE)
Message-ID: <000a01c40411$b5b8d180$c300a8c0@zxc>

Hello! 
  I use ACISR11+HOOPS800 to develop my program. I want to get a face entity when I pick a face in screen. Because every entity in acis has a key mapping from hoops database,I use the function HA_Compute_Entity_Pointer(key, FACE_TYPE) to solve it.The value of return is always 0. I had added api_initialize_hoops_acis_bridge() in my BOOL CHoop3App::InitInstance(). I don't know why it doesn't work.
  Any help is my appreciate!

zhang xuechang.
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From muthler at bv.tum.de  Thu Mar 11 09:41:40 2004
From: muthler at bv.tum.de (Alexander Muthler)
Date: Thu Mar 11 03:40:23 2004
Subject: [Acis-alliance] Reparam Spline Faces
Message-ID: <[e-mail]>

Dear Acis-Alliance,

I have several spline surfaces in an ACIS-BODY. Some of them are
arclength-paramtrized and I can reparametrize them by the corresponding
member-function.

But some surfaces are parametrized by u=[0,1] v =[0,1] and when I try to
reparametrize them, the program crashes.

What could be possible reasons for this?

Any help would be appreciated.

Best Regards,
Alex

From nfarnsworth at web.de  Sat Mar 13 17:02:56 2004
From: nfarnsworth at web.de ([e-mail])
Date: Sat Mar 13 11:03:23 2004
Subject: [Acis-alliance] Modify ACIS Shapes
Message-ID: <[e-mail]>

Hallo,
I am using the ACIS C-api functions and I want to create a sphere with 
the following source code:

outcome oc = api_solid_sphere(SPAposition(0.0, 0.0,0.0), m_dRadius, m_pAcisShape);

Is there a posibilty to modify the radius of the sphere after creation.
Thanks for your support
Niklas
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From luo at irs.fzk.de  Mon Mar 15 09:56:34 2004
From: luo at irs.fzk.de (Luo, Yue-Tong)
Date: Mon Mar 15 03:59:04 2004
Subject: [Acis-alliance] inconsistent containment of intersection curve
Message-ID: <[e-mail]>

Hi, All
 
I'm writing an application with ACIS 7.0MFC and I need to do regular
Boolean operation.
Sometimes I get an ACIS error "inconsistent containment on intersection
curve" during this operation.
I suppose it is because of tolerance limits, but I am not sure. Does
anybody tell me what the really reason, and how to avoid such error?
Any suggestion is welcome. Thank you in advance.
 
 
Yuetong Luo
 
 
 
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From alames at sandia.gov  Mon Mar 15 09:01:05 2004
From: alames at sandia.gov (Ames, Arlo)
Date: Mon Mar 15 11:01:49 2004
Subject: [Acis-alliance] Modify ACIS Shapes
Message-ID: <[e-mail]>

3 solutions:

1.  You have a body.  Walk its LUMP->SHELL->FACE, get the face's SURFACE.
The SURFACE can be cast as a SPHERE, which has a sphere which has the
parameter you're interested in.  Change the sphere's radius and move on.
You might have trouble if the body has cached info (e.g. box information)
that needs updated, I think if you use the right functions to make the
change the cached info goes away.

2.  A cheap hack is to create an appropriate scaling transf (note that
scaling also scales the position of the center of the sphere), do
api_apply_transf to the body, then api_change_body_trans(body,NULL) and the
parameter will change.  This transf approach changes the ENTIRE model -- it
isn't a local change.  It will get the job done.  Note that if you have a
more complex model (involving faces adjacent at edges) scaling the model
opens up or closes down gaps in the model that occur at intersections, which
can later cause problems with geometric operators like booleans.  If you
only have surfaces, or if you have simple quadric (non NURBS) surfaces
intersecting in simple (non NURBS) curves, you can also get away with this.

3.  The LOPS husk permits a wide range of mods to be made to models having
intersection edges; its limits are cases where you have topology changes.
Portability of your application to other geometric engines might be a
problem if you use LOPS (I've not yet found LOPS in other geometry kernels).

Of the three, I'd use 1 or 2 if I had a very simple model and needed it
quickly.  LOPS isn't at all difficult to learn, though, and is general
enough that for a model of any complexity it's the thing to do.

Arlo




-----Original Message-----
From: [e-mail] [mailto:[e-mail]] 
Sent: Saturday, March 13, 2004 9:03 AM
To: [e-mail]
Subject: [Acis-alliance] Modify ACIS Shapes


Hallo,
I am using the ACIS C-api functions and I want to create a sphere with 
the following source code:

outcome oc = api_solid_sphere(SPAposition(0.0, 0.0,0.0), m_dRadius,
m_pAcisShape);

Is there a posibilty to modify the radius of the sphere after creation.
Thanks for your support Niklas
______________________________________________________________________
Extra-Konto: 2,50 %* Zinsen p. a. ab dem ersten Euro! Nur hier mit 25
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From alames at sandia.gov  Mon Mar 15 09:15:35 2004
From: alames at sandia.gov (Ames, Arlo)
Date: Mon Mar 15 11:16:06 2004
Subject: [Acis-alliance] inconsistent containment of intersection
 curv e
Message-ID: <[e-mail]>

ACIS computes booleans by first constructing all the intersections
conditions (surface/surface, curve/curve, ...), then deciding how to limit
the intersections (what portions of the intersection curve are really on the
face), and resolving the model's topology.  The inconsistency you're finding
is that ACIS is getting conflicting (inconsistent) information about how the
curve is contained in the model.  It can think, for instance, that both
sides of a curve are present in a surface.
 
Fundamentally, boolean operations are not robust over the entire possible
space of geometric objects you might construct.  There really has never been
a complete theory developed, especially where we permit the models to have
gaps at edges.  Grazing cases, and models exhibiting inaccuracies, tend to
show such problems.
 
A variety of hacks exist, once you've trapped the error.  You can scale the
parts down (sometimes up) to close up gaps (or to make previously too-close
points distinct).  You can translate the parts closer to the origin to get
into the sweet spot of the floating point numbers.  You can simplify your
parts so they don't have so much unimportant (and generally destabilizing)
geometry.  You can locally adjust the positions of the offending faces/edges
so they aren't close to one another (this approach isn't so outlandish as it
seems -- look at Mulmuley, Computational Geometry for a scholarly treatment
of Randomized Algorithms; hacking the problem is a standard technique).
 
Understand that the most complete testing on booleans has been done in cases
of DESIGN operations, rather than arbitrary computer-generated operations.
Building CAD systems so designers can add holes, slots, etc is
bread-and-butter for most geometry engine writers, so that works a lot
better than, say, slicing a model with an arbitrarily located set of planes
(say for a rapid prototyping application).  So, expect a bit of brittleness
if you're automatically constructing your geometries, and think about little
tweaks that work around the brittleness.
 
The concern here isn't about ACIS vs other geometry representations.
Everybody has the problem.  Some work has been done in trying to implement
absolutely robust booleans, but even good theory on the problem is hard to
come by.  Even exactly representing the intersection curves would help, but
runs the computational and development burdens through the roof.
 
Arlo Ames
[e-mail]
 
-----Original Message-----
From: Luo, Yue-Tong [mailto:[e-mail]] 
Sent: Monday, March 15, 2004 1:57 AM
To: [e-mail]
Subject: [Acis-alliance] inconsistent containment of intersection curve


Hi, All
 
I'm writing an application with ACIS 7.0MFC and I need to do regular Boolean
operation.
Sometimes I get an ACIS error "inconsistent containment on intersection
curve" during this operation.
I suppose it is because of tolerance limits, but I am not sure. Does anybody
tell me what the really reason, and how to avoid such error?
Any suggestion is welcome. Thank you in advance.
 
 
Yuetong Luo
 
 
 
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From afxyang at tom.com  Wed Mar 17 10:47:44 2004
From: afxyang at tom.com (afxyang)
Date: Tue Mar 16 21:48:30 2004
Subject: [Acis-alliance] intersections between EDGE and FACE
Message-ID: <4057BC50.00007B.08082@bjapp8>

hello all:

I am using ACIS 5 and I am trying to get the intersections between the edge and the trimmed face by using api_edfa_int.

But I can't get the right results for two reasons. The first reason is the API always fails and the other one is the redundant intersections returned, that is, there are many unwanted intersections lying on the trimmed region.

With a EDGE and a trimmed FACE, how can I get their intersections locating on the untrimmed region of the trimmed FACE. How can I get rid of the redundant intersections.

thanks

afxyang
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From NFarnsworth at web.de  Wed Mar 17 17:34:47 2004
From: NFarnsworth at web.de ([e-mail])
Date: Wed Mar 17 11:35:32 2004
Subject: [Acis-alliance] create an ellipsoid
Message-ID: <[e-mail]>

Hello,
is there a posibilty to make from an ACIS Sphere an ellipsoid?
Thanks for your support
Niklas
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From juergen.wehr at stz-wuerzburg.de  Sun Mar 21 21:51:35 2004
From: juergen.wehr at stz-wuerzburg.de ([e-mail])
Date: Sun Mar 21 21:58:04 2004
Subject: [Acis-alliance] Mesh identify mesh geometry
Message-ID: <[e-mail]>

Hello,

I use the faceting algo to create mixed meshed (triangles and quads)
out of faces.

How can I identify if the mesh is a triangle, a set of triangles or a
quad or set of quads?

e.g.
I created a torus and meshed it. 99% are size 0f 4 vertices -> quad 
some breach exist, which are not size 4 or 3. (e.g. torus->5,
cylinder->6)

If I create a sphere and mesh/facet it, there's no problem -> only face
meshes size of 4 and 3 :-)


thank you very much for your support