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Voxel Generators and Editors
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This list was generated with the goal of making a 3 dimensional torus.  Not
just aligned but rotated in two axis (not axially aligned)

Getting a voxel torus aligned with an axis is easy, using basic math formula.
Getting a foruma for one that has been rotated -- Near impossible!

ASIDE: I ended up storing and processing 3D voxel shapes in a sequence of 2D
'layer images'.  Shapes can be created and images saved using perl scripts to
write PBMPlus images.  ImageMagick scripts could take those image sequences to
hollow out the shapes, contanted in the images.

Later I discovered you can use mathematical expressions in WorldEdit //g
command, and but rotating the x,y,z coordinates before applying the torus
formula you can rotate it so as to directly generate a slanted (or otherwise
distorted) toruses, and much much more.  I created a sequence of YouTube videos
explaining that process.

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MinecraftStructurePlanner  (Java)
  http://minecraftstructureplanner.com/

  Not really a voxel generator but specialised minecraft structure generator

  Generate many different pre-defined structures
    arch, suspended, viaduct  bridges
  Basic objects  (even diameters only - integer pixels)
    spheres, torus

  A little clunky in processing, but bridge templates are good.
  Level images shows the level below, but does not show the one above.

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WorldEdit in Minecraft

  Best Voxel Editor for generating shapes I have seen is using the //generate
  command.  This not only can do basic math shapes, but can also warp space so
  as to distort those shapes.

  For example...
    * Spheres, cylindars, cones, funnels, planes and, intersections of them
    * Rotate a torus to any angle (during generation not afterwards)
    * Arch a cylinder to shapes like the Dallas Airport Sky Arch
    * Twist and distort a cylinder into a true helix (tileable)

  Combine it with the UNDO, and saving or modifing equations in a notepad.
  This lets you incrementally adjus the expression until you get exactly
  what you are looking for.

  The best guide is the videos in
    Ant's Minecraft, World Edit Series
      https://www.youtube.com/playlist?list=PLk6dEnwETd5_9lFuBv-c-NkI_LH6GU_C5

Plotz (www only)
  http://www.plotz.co.uk/

  Spheres, ellipsoids, torus and a few other simple pre-defined structures

  Display is great with 2d, and even 3d both with cross sections
  torus can be axis rotated for generating cross sections!

  But no random rotations or other shapes.

  For 90 degree Rotated toruses, with printouts use...
    http://www.plotz.co.uk/plotz-flash.php

binvox
  http://www.patrickmin.com/binvox/

  binvox is a straight-forward program that reads a 3D model file,
  rasterizes it into a binary 3D voxel grid, and writes the resulting
  voxel file.

  A slow viewer is provided a viewvox

  input formats: nearly 100% VRML 2.0 support
    Wavefront OBJ, Geomview OFF, Autocad DXF,
    PLY and STL,
    if they contain polygons only VRML 1.0 support added in version 1.08
      Unigrafix UG, VTK, XGL, PovRay POV, BREP, and JOT (disabled)
  output formats:
    .binvox, HIPS, MIRA, VTK, a "raw" file format, minecraft .schematic format,
    Gmsh .msh format, and nrrd format

  runs fast if you have a current graphics card
  rasterizes to a cube grid of up to
     1024x1024x1024 (if you have enough memory...)

  See info/apps/binvox.txt  for how to use.


UVOX
  http://tox.land/uvox/vendors.html

  Voxel File Format converter

MagicaVoxel (win only)
  https://voxel.codeplex.com/

  Can rotate voxels over any axis
  Also dilate/erode, and remove/fill invisible pixels
  can generate spheres, ellipsoids, cylinders, cones, pyramids, and perlin
  But NOT a torus!


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