[quote user="quasi_modo"]
I have got the following details:
- slope angle
- angle of the slant edge
- width of the roof
- width, length, height of the beam
[/quote]
When dealing with 3D geometry, work with vectors, transformations and matrices. MicroStation VBA is well furnished with methods that operate on a variety of 3D data types, including Vector3d, Transform3d, Matrix3d and others.
Use linear algebra to perform 3D manipulations and calculations. Convert to angles and linear metrics for human consumption when you've finished the 3D stuff.