Format of shape-files

Definition of a shape

A shape-file is a library of shapes, which is in fact a file with a number of shapes defined between brackets (starting with < and ending with >). To run a simulation, we need that all required shapes are defined in a single shape-file. The keywords are given here after:

  • name (string) shapeName

    The name of the shape (without space). When the particles are listed in a conf-file, its shape is referred to as this defined keyword

  • radius (double) MinskowskiRadius

    The radius of the rounded edges (so-called Minskowski radius) of the shape (there is only one radius per sphero-polyhedron)

  • preCompDone y or n

    If yes, the computation of mass properties will not be run at the beginning of a computation in Rockable or in the program shapeSurvey

  • OBBtreeLevel (int) number

    (deprecated) set the number of levels for building an OBB-tree

  • nv (int) numberOfVertices

    Then repeat numberOfVertices times:
    (double) x (double) y (double) z

  • ne (int) numberOfEdges

    Then repeat numberOfEdges times:
    (int) from (int) to

  • nf (int) numberOfFaces

    Then repeat numberOfFaces times:
    (int) numberOfVertices [(int) V1 (int) V2 …]

  • obb.extent (double) extent1 (double) extent2 (double) extent3

    The 3 components of the extents in the 3 directions defined by obb.e1, obb.e2 and obb.e3

  • obb.e1 (vec3r) e1

    Extent unit vector in the first direction

  • obb.e2 (vec3r) e2

    Extent unit vector in the second direction

  • obb.e3 (vec3r) e3

    Extent unit vector in the third direction

  • obb.center (vec3r) center

    Position of the OBB center relative to the mass center of the shape, given in the framework (principal direction of inertia) of the shape

  • volume (double) V

    Volume of the shape

  • I/m (double) I1/m (double) I2/m (double) I3/m

    Eigenvalues of the moment of inertia divided by the mass. It supposes that the positions of the vertices are given in the eigen-frame of the shape

  • position (vec3r) pos

    A position that can be stored for processing purpose. Most of the time, it is not useful to define this position, but it is actually a position reminder generated by an automated pre-computation

  • orientation (quat) Q

    As the position defined previouly, an orientation can also be stored for processing purpose

As an example, this is how a cube with unit side can be defined (radius of 0.1):

<
name Cube_r0.1
radius 0.1
preCompDone y

nv 8
0.4 0.4 -0.4
-0.4 0.4 -0.4
-0.4 -0.4 -0.4
0.4 -0.4 -0.4
0.4 0.4 0.4
-0.4 0.4 0.4
-0.4 -0.4 0.4
0.4 -0.4 0.4

ne 12
0 1
1 2
2 3
3 0
4 5
5 6
6 7
7 4
0 4
1 5
2 6
3 7

nf 6
4 0 1 2 3
4 4 5 6 7
4 0 1 5 4
4 2 3 7 6
4 1 2 6 5
4 0 4 7 3

obb.extent 0.5 0.5 0.5
obb.e1 1 0 0
obb.e2 0 1 0
obb.e3 0 0 1
obb.center 0 0 0

volume 0.975587
I/m 0.166667 0.166667 0.166667
>