Fabrication: between C and rhino scripting

1
Fabricationbetween C and rhino scripting

• Offset surface planar ?solid tiles
• Exploit connectivity information of voronoi cells
• Unrolling
• Rotation arbitrary position orientation ?
  common ground plane
• Bolt placement
• Record features for bolted edges
• Vertex merging
• Remove seams from lofted surfaces

2
User Interfacecreating and visualizing tiles
- tile depth - unroll - save as - visualize

3
User Interfacecreating and visualizing tiles
- tile depth - unroll - save as - visualize

4
User Interfacecreating and visualizing tiles
- tile depth - unroll - save as - visualize

5
Voronoi Propertiessmart cells ? connected and
planar

• Cells planar
• Constraint
• All vertices lie on a plane
• General case
• Always true for 3 vertices
• Rarely true for gt3 vertices
• Only 3 cells meet at a point
• 2 planes intersect on a line
• 3 planes intersect at a point
• gt 3 planes do not
• Intelligent each cell knows
• Neighboring cells
• Plane normal
• Edges and vertices

6
Voronoi Propertiessmart cells ? connected and
planar

• Cells planar
• Constraint
• All vertices lie on a plane
• General case
• Always true for 3 vertices
• Rarely true for gt3 vertices
• Only 3 cells meet at a point
• 2 planes intersect on a line
• 3 planes intersect at a point
• gt 3 planes do not
• Intelligent each cell knows
• Neighboring cells
• Plane normal
• Edges and vertices

7
offset surfaceexploit connectivity of voronoi
cells

• back face vertices
• give all cells constant thickness
• back face also planar
• for (every cell)
• for (every vertex)
• // find 3 neighbor cells sharing vertex
• // offset planes along normal vector
• // create new vertex at intersection pt
• Special case cell on surface boundary
• only 2 neighbor cells
• new vertex along line intersection
• Offset along average of 2 normals

8
unroll tilesarbitrary orientation ? common
ground plane

• Rotate each cell
• ? align normal with z-axis
• the math
• axis of rotation
• ( z-axis ) x ( normal )
• vector perpendicular to both
• angle of rotation
• angle between z-axis, normal

9
Bolt placementembedding edge information for
rhino scripting

• Extra geometry in obj file
• Triangle on each bolted edge
• Vertex 1 midpoint
• Vertex 2 normal to tile face
• Vertex 3 normal to tile edge
• Size ¼ edge length
• Boundary of surface
• Test number of neighbor cells to recognize
  boundary
• No bolt, no triangle

10
Seam removalmerging vertices on loft surfaces

Lofted surfaces create copied vertices ? 2 copies
of each vertex Case 1 Start and end curve Case
2 Curve midway through loft Result Interpreted
as a boundary
11
Seam removalmerging vertices on loft surfaces

Obj file format list of vertices ? each with
x,y,z coordinate list of faces ? References
vertex index v 0.2761 1.1840 0.5920 v
0.2546 1.0462 0.5291 f v v
v f 10 24 15 f
11 24 15