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Add information about 3D asset direction conventions to "Importing 3D scenes" #7406

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merged 1 commit into from
May 29, 2023

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aaronfranke
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@aaronfranke aaronfranke commented May 24, 2023

This PR adds a note to the documentation to explain the different conventions and specifications about orienting 3D assets in Godot. It explains Godot/OpenGL camera directions, Godot/Blender/glTF asset directions, and Godot/Blender cardinal directions. It links to the glTF specification for +Z being codified as asset front. I tried to be careful where I use the words "forward" vs "front" to make things clear.

Why not open this PR earlier: Before we were not certain what would end up in the engine, but now it is fairly certain so now seems like a good time. For example initially there was some push from @TokageItLab to add GLTF_* constants and document how glTF works in the core engine. I fully agree that this information must be documented, I just disagreed on it being in the core engine's constants and documentation, so now it can live in the docs repo :)

I'm fully open to feedback on any ways we can make this documentation more clear, concise, and comprehensive. I think we can all agree that coordinate systems are a confusing topic.

The third paragraph in this PR refers to the use_model_front option and the MODEL_* constants, so it expects that godotengine/godot#75875 and/or godotengine/godot#72842 is merged into the engine.

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I thinks it's fine. However, as mentioned in godotengine/godot#75228, there is often confusion in the handling of coordinates in Blender, so I would like to add another troubleshooting page separate from this.

Comment on lines +36 to +40
the camera's forward direction. This is the same as OpenGL. This implies
that +Z is back, +X is right, and -X is left for a camera.

The convention for 3D assets is to face the opposite direction as the camera,
so that characters and other assets are facing the camera by default.
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This part is confusing me (and making me realize my 3D teachers in college taught even less than I thought, which wasn't much). What exactly is "the camera" that you're referring to here? I assume it's not one you would attach to a player character

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@aaronfranke aaronfranke May 25, 2023

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@skyace65 Does this image help you understand?

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It may be paraphrased as a viewpoint of the viewport.

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So the camera in this case would be the viewport camera when you a open a blank scene?

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In most cases, yes.

@skyace65 skyace65 added the area:manual Issues and PRs related to the Manual/Tutorials section of the documentation label May 25, 2023
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mhilbrunner commented May 29, 2023

@aaronfranke Any part of this that still needs to be discussed? (i.e., the discussion label) - it seems like a good improvement from my POV

@aaronfranke aaronfranke merged commit fee03be into godotengine:master May 29, 2023
@aaronfranke aaronfranke deleted the 3d-asset-directions branch May 30, 2023 04:41
mhilbrunner pushed a commit that referenced this pull request Aug 1, 2023
Add information about 3D asset direction conventions to "Importing 3D scenes"
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4 participants