The Complex Pitched Roof
Algorithm builds off of the Geometric
Boolean Operation Algorithm Suite to allow the creation of a
multi-wing pitched roof building structure with minimal user inputs.
The user only needs to define the shape of the gutterline, select
the a point on each gutterline, and select a point on the ground.
With these inputs the algorithm generates a full volumetric pitched
The algorithm operates
in two stages, first the gutterline is drawn. This gives the algorithm
the general shape of the building. The shape is interpreted and
the algorithm determines where the ridgelines are likely to be located.
For this E-shaped building, the algorithm finds four potential ridgelines
from the gutterline shape.
guess locations are coplanar with the building gutterline. Depending
on the heights of each ridgeline, the building shape can change
in structure, so the ridgeline guesses are not drawn in the ambiguous
zones (i.e. the intersection zones between orthogonal wings). The
user then must select the height and skew of the ridgeline. The
initial guess of the ridgeline peak is in the middle of the wing,
but may be located skewed to the left or right. The user also selects
the distance to the ground.
allows the ridgeline structure to be determined. For this algorithm,
the lower ridgeline peaks are always assumed to terminate at the
taller ones and same height ridgelines always form a hip roof intersection.
This is a good assumption for most buildings, but more complex roof
structures (like Dutch Gables) can still be drawn manually added
using the Boolean tool suite. The wing path sections are shown below.
are used to create primitve sections of the building. The red and
orange paths represent simple extrusions, the cyan path is a swept
(non-linear extrusion) path. Note: the paths are centered
in each wing, but if an offset is inserted into the ridgeline location,
the primitive will be drawn with the rooftop asymmetric.
are finally unioned into a composite object. Because the orange
and green ridgelines were selected to be at the same height, those
wings create a flat hipped roof intersection. The higher ridgeline
in the red wing causes the ridgeline to extend all the way to the
back of the building and the green ridgeline to terminate inside
the red wing.
can be used to generate many pitched roof variants.