This is not a "simple" question!
Now, having screamed a bit, let me be more helpful. In the way you have phrased your question I assume, you are assuming, that CAD-drawings can be handled easily in .net. it's not easy, and 3D is ten times harder. It would be helpful to know what kind of application you are working on.
Now, you are in luck... AutoCAD has API's for .net, but it seems is more for plugins and similar, it looks like it could lead you to what you need.
AutoCAD .net Dev Guide[
^]
If you only need a 2D CAD-system, look at this:
OpenS-CAD, a simple 2D CAD application[
^] - It's a codeprocject article.
Take a look at these other codeproject articles, they may help you:
SolidGraph CAD System[
^]
WPF 3D Dome Creator[
^]
WPF 3D Primer[
^]
Plot 3D surfaces[
^]
DXF Import .NET: Read and View AutoCAD Format Files[
^]
A 3D Plotting Library in C#[
^]
This is semi-relavant:
ColladaLoader[
^] - Sourcforge project
Have a look, maybe you'll find that perfect snippit of code to solve your problem :-)
Good Luck!
-Frank
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