yang686526

acis 3d solids questions
acis 3d solids questions
hi,
we are developing a 2d/3d cad system, which uses in some parts the dwgdirect software.
we would like to support also 3d solids and boolean operations on them and not only polygon and polyface meshes. one of the ways to achieve it seems to be using of 3d solids (widely used in autocad), which are parts of the acis modelling system. in autocad objectarx you cannot query a 3d solid directly for being cube, sphere, etc. rather you take a void* to the internal acis data and pass this to the acbr library to do some traversals. the questions are:
1. is the odbr library fully implemented?
2. what is needed to support the boolean operation over 3d solids?
3. how to access the full geometry of an acis object - we need to draw them but not with the dwgdirect rendering capabilities.
4. is there some acis library we can buy, which is not the full acis version? (the full version seems to support too many things and is too expensive for us).
5. if possible, can someone of the dwgdirect guys explain the way you use to draw the 3d objects in the odgs system?
thanks in advance for any help.
regards
chudomir
best regards
chudomir

>>>in autocad objectarx you cannot query a 3d solid directly for being cube, sphere, etc. rather you take a void* to the internal acis data and pass this to the acbr library to do some traversals.
this is because real mechanical (or other) parts usualy are not a cube or sphere but a result of a number of boolean operations. they have a number of faces each defined by specific surface type: plane, sphere, cone, ..., nurbs surface.
>>>1. is the odbr library fully implemented?
at least most functionality is implemented. dwgdirect rendering code uses br interface to parse the data while calculating wireframe or mesh.
>>>2. what is needed to support the boolean operation over 3d solids?
you need to implement it or to use some library. currently dd does not have any functionality to perform boolean operations.
>>>3. how to access the full geometry of an acis object - we need to draw them but not with the dwgdirect rendering capabilities.
currently you can get
- sat data
- geometry via br interface
- wireframe or mesh via worlddraw()
in next release it will be possible to get sab data too.
>>>4. is there some acis library we can buy, which is not the full acis version? (the full version seems to support too many things and is too expensive for us).
i have not heard about such libraries.
>>>5. if possible, can someone of the dwgdirect guys explain the way you use to draw the 3d objects in the odgs system?
sat data is parsed into internal structure. rendering code traverses it via br interface and calculates wireframe or mesh (to send it to worldgeometry via shell primitive)
sergey slezkin

thank you very much for your reply, sergey.
so i suppose we can use the rendering functionality if we want to convert a 3d solid to a mesh with some approximation. i mean inheriting some odgs class which do not render but stores mesh in the database - its better than nothing.
thank you once again.
regards
chudomir
best regards
chudomir