Robert Swain bdef86ea6e Generate vertex tangents using mikktspace (#3872) ... # Objective Models can be produced that do not have vertex tangents but do have normal map textures. The tangents can be generated. There is a way that the vertex tangents can be generated to be exactly invertible to avoid introducing error when recreating the normals in the fragment shader. ## Solution - After attempts to get https://github.com/gltf-rs/mikktspace to integrate simple glam changes and version bumps, and releases of that crate taking weeks / not being made (no offense intended to the authors/maintainers, bevy just has its own timelines and needs to take care of) it was decided to fork that repository. The following steps were taken: - mikktspace was forked to https://github.com/bevyengine/mikktspace in order to preserve the repository's history in case the original is ever taken down - The README in that repo was edited to add a note stating from where the repository was forked and explaining why - The repo was locked for changes as its only purpose is historical - The repo was integrated into the bevy repo using `git subtree add --prefix crates/bevy_mikktspace git@github.com:bevyengine/mikktspace.git master` - In `bevy_mikktspace`: - The travis configuration was removed - `cargo fmt` was run - The `Cargo.toml` was conformed to bevy's (just adding bevy to the keywords, changing the homepage and repository, changing the version to 0.7.0-dev - importantly the license is exactly the same) - Remove the features, remove `nalgebra` entirely, only use `glam`, suppress clippy. - This was necessary because our CI runs clippy with `--all-features` and the `nalgebra` and `glam` features are mutually exclusive, plus I don't want to modify this highly numerically-sensitive code just to appease clippy and diverge even more from upstream. - Rebase https://github.com/bevyengine/bevy/pull/1795 - @jakobhellermann said it was fine to copy and paste but it ended up being almost exactly the same with just a couple of adjustments when validating correctness so I decided to actually rebase it and then build on top of it. - Use the exact same fragment shader code to ensure correct normal mapping. - Tested with both https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/NormalTangentMirrorTest which has vertex tangents and https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/NormalTangentTest which requires vertex tangent generation Co-authored-by: alteous <alteous@outlook.com>		2022-05-31 22:53:54 +00:00
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regression_test.rs	Generate vertex tangents using mikktspace (#3872)	2022-05-31 22:53:54 +00:00