Thursday, 25 March 2010

Force Density Relaxing Roofs

Arthur Mamou-Mani posted on the Grasshopper forum ( ) about tensile membranes and Rhino plug-ins that can compute shapes and forms.

I thought the problem looked interesting, and thought I'd see what I could achieve with the new mesh minimal surface tools I've been improving in StructDrawRhino.

You need the latest version of BullAnt ( ) and a license file, but you can try this for yourself.
Note, if you altering the inputs such as the control curves, I'd recommend disabling the Grasshopper meshing component temporarily, and then reconnecting it when you want to recompute.

Rhino Model
Grasshopper Definition             

What you find in the basic definition, is that the isolated mesh restraint points produce a very pointed roof, in reality we wish to strength the links along the ridge line.

Here's a revised definition that produces a more desirable result
Strengthened Ridge Line Grasshopper Definition 

Note that the image shows the mesh baked, which helps identify the isocurves or underlying mesh.  Toggling the preview update input can give some insight into how the algorithm is working, at the expense of a slower result.

Sunday, 21 March 2010

Costa Minimal Surface

Force Density (Using the Mesh Vertex Repel command)

Grasshopper Definition     

This definition calls on the ggForceDensity Relax functionality to compute a minimal surface discovered by Costa.  This command doesn't compute minimal surfaces for all mesh, but at least seems to give a reasonable impression for Costa Minimal Surface.

Here's a generic model to also test it.

Grasshopper Definition     

Note, that unless you have a quick computer (or a lot of patience), it's probably worth disconnecting at the Mesh component (or disabling) and previewing the surface if you wish to adjust the sliders for variations.

Arc Poly Curve Extrusion boundary Minimal Surface

Grasshopper Definition

There is also capability to restrain mesh vertex to nominated points, curves and surfaces.  Some examples demonstrating this will be posted soon.

Tuesday, 16 March 2010

Cell Filleting a Curve Network

Files :
Rhino Model  
Grasshopper Model   -  Previous  Grasshopper Model

Files : 

Note that you will need an approved, valid license file for these commands to work.  The BullAnt plug-in can be downloaded from 

If you find any unexpected results in your own models, please let me know and I will review them.

Monday, 8 March 2010

BullAnt GrassHopper Geodesic Dome

This example file demonstrates calling on the BullAnt Geodesic dome function from within Grasshopper, as well as sweeping structural profiles including member orientation. Try for yourself, but you'll need a valid license (or free trial license) file to do so.
Previous Versions