This paper describes a precise geometric method for the inscription of
structural constraints into architectural form. Based on techniques from graphic statics, the force distribution in building structures is visualized using geometric diagrams. This diagrammatic representation allows a formal description that shows the relationship between the force flow and the structural form. The formal character of this description enables the direct implementation of a parametric
truss geometry that maintains major structural behavioral characteristics under deformation. An interactive model of a structural freeform roof is developed through this link between a parametric truss definition and a design-driving NURBS surface. This allows for an intuitive exploration of the constrained design space in real time. Formal explorations and the comparison with built examples
demonstrate the effectiveness of this approach.