Python OpenGL program to generate triangle meshes of various scalar fields using the marching cubes algorithm.

The program requires pyopengl, glfw, pyglm, and numpy. For help setting up a new Python environment and downloading the packages, check out my beginner PyOpenGL tutorial, Hello Triangle!

The program is divided into two modules to optimize performance:

marching_cubes.py

Generates triangle meshes and saves the data to a PLY file

render.py

Opens the triangle mesh data from a PLY file and renders the result

Triangle meshes are generated with the marching cubes algorithm. To generate a triangle mesh of a scalar field, execute

python marching_cubes.py filename scalar_field isovalue volume_min volume_max
stepsize

filename

Filename of the PLY file to write triangle mesh data to.

scalar_field

Name of the scalar field defining the object to generate a triangle mesh for.
Options:
 wavy : Scalar field f(x, y, z) = y − sin (x) ⋅ cos (z)
 hyperboloid : Scalar field f(x, y, z) = x² − y² − z² − z

isovalue

Boundary value used to define which points are considered to be inside of the object.
  If f(x, y, z) < isovalue, then the point (x, y, z) is considered to be inside of the object. If f(x, y, z) > isovalue, then the point (x, y, z) is considered to be outside of the object.

volume_min

Minimum value of x, y, and z to use in the algorithm.

volume_max

Maximum value of x, y, and z to use in the algorithm.

stepsize

Side length of each cube in the algorithm. A smaller stepsize will result in more vertices in the triangle mesh.

To render a saved triangle mesh, execute

python render.py filename volume_min volume_max colour

filename

Filepath to the PLY file containing the triangle mesh's attributes.

volume_min

Minimum value of x, y, and z in the marching volume. For best results, this should match the value used to generate the triangle mesh.

volume_max

Maximum value of x, y, and z in the marching volume. For best results, this should match the value used to generate the triangle mesh.

colour

Name of the object's base colour. Used as the diffuse component of the lighting model.
Options: turquoise, lime, orange, purple, fuchsia
 If not specified, turquoise is used by default.

To render the object, the program uses a Phong-like shader which combines the the ambient, diffuse, and specular components of light to compute the object's colour. A box is drawn around the marching volume, with the x, y, and z axes indicated in red, green, and blue respectively. Once the scene is rendered, the cube can be rotated in place by clicking and dragging the mouse. The camera can be zoomed in and out using the up and down arrow keys respectively.

Example PLY files that can be used to experiment with the program have been provided in the directory Example-Files. The parameters used to generate each triangle mesh are included as a comment in the file. The following images show each triangle mesh rendered. The code to generate and render each triangle mesh is included in the caption.