Mark Stock

Rocktools

Rocktools is a collection of command-line tools for the creation and manipulation of open or closed triangular meshes in 3D space. It is especially adept at detailing triangular meshes according to three-dimensional random walks. It is written in ANSI C and only requires libpng and the standard C libraries to compile. Thanks go to Steven Pigeon for his program POVRockGen 1.0, which gave me the idea for creating rocktools. There is also a program called MacRock that uses the above code.

Files

Rocktools is now being hosted at https://github.com/markstock/rocktools. On a Unix system, you should be able to run the following commands:

git clone https://github.com/markstock/rocktools.git
cd rocktools
make


Most tools take the -h option and will echo usage and a list of available options.

Features

Rocktools includes the following programs

• rockconvert can convert obj, raw, msh, or tin files into raw, rad, pov, obj, tin, or rib files; surface normals and texture coordinates are not always preserved
• rockcreate creates rock-like triangle meshes from the convex hull of a distribution of points, it is ideal for creating starter meshes; see the rockcreate options page; program is now self-contained and includes new options for point initialization
• rockdetail recursively roughens a triangular mesh by splitting each triangle into three or four new triangles; see the rockdetail options page; new spline-fitting and perturb-all-nodes schemes result in much higher-quality meshes, see images below
• rockdice recursively split a (large) trimesh file into smaller files using rocksplit and convert them all to Radiance triangle mesh files (Perl script)
• rockerode iteratively erode a triangular mesh file, moving mass from hills and elevated areas, and creating valleys and watersheds
• rockinfo dumps node and triangle counts, and min/max bounds of tri mesh
• rockmarker is designed to write out simple markers (spheres or rectangles) aligned to and upon a triangle mesh
• rockpng creates a trimesh from a greyscale PNG heightfield
• rocksmooth removes sharp corners via a Laplacian smoothing filter and calculates surface normals; see the rocksmooth options page
• rocksplit splits a trimesh into two meshes along an axial plane
• rocktrim selectively removes triangles from a triangle mesh file based on bounds in global x, y, and z directions
• rockxray will create a PGM or PNG "x-ray" or density image of a mesh

Images

An 8-level detailing of an icosahedron illustrating the distance-dependent detaling option; the command was rockdetail icosahedron0.obj -d 8 -dt .1 1 0 0 -oobj > partial8a.obj

A 7-level detailing of a hexagon using the edge-clamping feature; the command was rockdetail hex0.obj -seed 12 -ce -d 7 -n 0.2 -b 0 -oobj > hex7b.obj

A 7-level detailing of a simple rock

Here's a view of the results of the rockerode tool. The erosion algorithm still needs work.

This image is a preview of the threshholding feature in rockdetail. It shows selective triangle splitting based on distance from an arbitrary viewpoint.

A MPEG animation made by varying the rockdetail parameters (1.6 MB), thanks to Jeff Balcerski

Output of rockxray with the "-s" (surface) option

Output of rockxray with the "-v" (volume) option

Future plans

Future versions of Rocktools may include the following:

• More realistic erosion behavior (lakes, waterfalls, landslides)
• Reading multiple input files, and reading from stdin
• More tools and input/output formats
• Volume-conserving smoothing
• Shattering a closed mesh into properly-fitting pieces

Please e-mail me if you'd like to see some particular feature in Rocktools, or if you use it to make something creative.

References

Rocktools has been used in the following research:

C.L. Lin and J.D. Miller, 3D characterization and analysis of particle shape using X-ray microtomography (XMT), Powder Technology 154 (1) 61-69, (2005) [link]