Add cubemap template images to Importing images

[Calinou]

Images were generated using https://github.com/Calinou/godot-cubemap-generator.

I have two questions though:

• The X axis seems to be inverted when I display the cubemap using a sky shader. In the project linked above, I've had to swap the X+ and X- images' positions for the cubemap display to look correct in example_cubemap_display.tscn (the image is included in the repository).

• The whole cubemap texture is also flipped (for the X and Z axes) when displayed as a sky shader. You can notice this if you set the shader parameter in the sky shader of example_cubemap_display.tscn to display one of the cubemap template images; letters will appear flipped.

Once I figure out these issues, I can look into adding more documentation and templates for cubemap arrays. (I've already started by mentioning that they only work with Forward+/Mobile, not Compatibility, due to OpenGL not supporting cubemap arrays until OpenGL 4.x.)

[skyace65]

How standardized are cubemaps across engines/3D software? If they are standardized it seems odd to add templates.

[Calinou]

How standardized are cubemaps across engines/3D software? If they are standardized it seems odd to add templates.

They aren't really standardized as far as I can tell. It was common for engines to use 6 separate images back in the day (Quake 2/3 with its _rt, _lf, _up, _dn, _ft and _bk suffixes, which the Cube Engine also adopted).

Godot expects a single image, which makes file organization easier, but you need this template if you're converting a cubemap from another engine to make sure the orientation of all faces is right.

Basis Universal does have this comment which matches Godot's ordering: https://github.com/godotengine/godot/blob/c73ac74c4a44ccfed158b3603f809a24590bac0a/thirdparty/basis_universal/transcoder/basisu_file_headers.h#L77

However, it does not specify in which layout the source texture should be specified (it can be 1×6, 2×3, 3×2 or 6×1).

I suppose this can only get less standardized as I investigate cubemap array importing 🙂

[mhilbrunner]

cc @clayjohn :)

[mhilbrunner]

Merged. Thanks! 🎉