Python script to generate skybox image maps in rectangular format from equirectangular images, as well as a setup for Blender to render equirectangular image maps.
With the Blender setup, an equirectangular HDRI can be rendered from a 3D environment, like the following:
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.. to then convert this into a cubemap with the Python script…
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… so that this can be used in game engines like Verge3D or Goldsource.