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Simple OpenGL Renderer

This is a very basic OpenGL renderer written in Python.

It currently requires PyOpenGL and Python 2.7+. It should be Python 3 compatible, but PyOpenGL currently does not work with Python 3 so Python 2 is required.

Usage

Current usage is as follows: $ python draw.py test.ply

Once the OpenGL window has appeared, the controls for the window are:
  • +/- zooms in/out
  • Arrow keys rotates
  • Shift+Arrow keys translates

The only supported file format right now is the Stanford Polygon Format. The file's extension must be .ply. It must contain two element types, 'vertex' and 'face'. vertex must at minimum have properties 'x', 'y', and 'z', and face must have a 'vertex_indices' property of type list. This matches the nomenclature used by blender's ply export script.

Extension

Adding support for new file formats is relatively easy. Add a file in the filetypes directory. This must contain a special function called 'register' taking one argument. Its argument will be a dictionary mapping file extensions to parsing functions. These parsing functions take a file name (string) as an argument and return a Mesh object. As an example:

import Mesh

def parse_myformat(fname):
        m = Mesh()
        for line in open(fname, 'r'):
                pass #parse file
        return m

# The name of this function must be 'register':
def register(handlers):
        handlers['myformat_extension'] = parse_myformat

The Mesh class has two significant methods. addVertex() adds a vertex to the Mesh (see the Vertex class - it's fairly simple). addFace() adds a face to the Mesh (see the Face class - again, simple). Note that faces' vertex members are currently indices into the array of vertices stored by the Mesh object. So a face (0, 1, 2, 3) is a quad defined by the first four vertices added to the mesh.

TODO

The code has practically no error handling. Everything works if the filename exists and parses correctly. However, it does not fail gracefully.

The Mesh object should create a vertex buffer (at least of quads and tris) in order to optimize drawing the object. This is unimplemented right now because it's a performance improvement, not a correctness improvement.

Lighting should be configurable.

The ply parser is not currently robust at dealing with attribute names that are not the same as those expected (i.e. those output by blender's export script). This should be easy to deal with, but one needs to know what other commonly-used attribute names are 'out there' in the wild. If the parser encounters unknown attributes, it should give the user the opportunity to define which slots these correspond with at runtime.

It would be nice to have a nice wxPython GUI, while preserving the ability to render from the command line. Perhaps the command-line could become a non-interactive renderer?