GLNebula is a system designed for the real-time visualization of planetary nebulae models (and in general, any static one-component scalar field, provided that the data is in the correct form). produced by three-dimensional photoionization codes such as Cloudy 3D.

GLNebula is free software and is licensed under the GPL

It uses three files: each one represents the emission values of one ionized element inside the nebula. The files are arranged in a cubical grid with one scalar per cell (see the File structure section of the manual), by using particles to represent each cell, real-time framerates can be achieved with large grids while keeping the appearance of being a full volume.

Each file is assigned to a particular color channel, so the scalar values of every element correspond to a certain color intensity, which coupled with color blending, transparency and texture support, preserve realism (see the screenshots section).

Due to the fact that the models tend to be of a very high resolution and that the program is using some OpenGL extensions not supported by integrated GPUs, a relatively modern video card is most recommended (a GeForce 2mx or equivalent is the minimum).

GLNebula is written in C/C++, using OpenGL and fltk for the user interface.