bdef86ea6e
# 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>
260 lines
6.9 KiB
Rust
260 lines
6.9 KiB
Rust
#![allow(clippy::bool_assert_comparison, clippy::useless_conversion)]
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use glam::{Vec2, Vec3};
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pub type Face = [u32; 3];
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#[derive(Debug)]
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struct Vertex {
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position: Vec3,
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normal: Vec3,
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tex_coord: Vec2,
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}
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struct Mesh {
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faces: Vec<Face>,
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vertices: Vec<Vertex>,
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}
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fn vertex(mesh: &Mesh, face: usize, vert: usize) -> &Vertex {
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let vs: &[u32; 3] = &mesh.faces[face];
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&mesh.vertices[vs[vert] as usize]
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}
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impl bevy_mikktspace::Geometry for Mesh {
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fn num_faces(&self) -> usize {
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self.faces.len()
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}
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fn num_vertices_of_face(&self, _face: usize) -> usize {
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3
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}
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fn position(&self, face: usize, vert: usize) -> [f32; 3] {
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vertex(self, face, vert).position.into()
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}
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fn normal(&self, face: usize, vert: usize) -> [f32; 3] {
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vertex(self, face, vert).normal.into()
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}
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fn tex_coord(&self, face: usize, vert: usize) -> [f32; 2] {
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vertex(self, face, vert).tex_coord.into()
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}
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fn set_tangent_encoded(&mut self, tangent: [f32; 4], face: usize, vert: usize) {
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println!(
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"{face}-{vert}: v: {v:?}, vn: {vn:?}, vt: {vt:?}, vx: {vx:?}",
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face = face,
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vert = vert,
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v = vertex(self, face, vert).position,
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vn = vertex(self, face, vert).normal,
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vt = vertex(self, face, vert).tex_coord,
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vx = tangent,
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);
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}
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}
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fn make_cube() -> Mesh {
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struct ControlPoint {
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uv: [f32; 2],
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dir: [f32; 3],
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}
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let mut faces = Vec::new();
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let mut ctl_pts = Vec::new();
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let mut vertices = Vec::new();
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// +x plane
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{
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let base = ctl_pts.len() as u32;
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faces.push([base, base + 1, base + 4]);
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faces.push([base + 1, base + 2, base + 4]);
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faces.push([base + 2, base + 3, base + 4]);
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faces.push([base + 3, base, base + 4]);
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ctl_pts.push(ControlPoint {
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uv: [0.0, 0.0],
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dir: [1.0, -1.0, 1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 1.0],
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dir: [1.0, -1.0, -1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [1.0, 1.0],
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dir: [1.0, 1.0, -1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [1.0, 0.0],
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dir: [1.0, 1.0, 1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.5, 0.5],
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dir: [1.0, 0.0, 0.0],
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});
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}
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// -x plane
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{
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let base = ctl_pts.len() as u32;
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faces.push([base, base + 1, base + 4]);
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faces.push([base + 1, base + 2, base + 4]);
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faces.push([base + 2, base + 3, base + 4]);
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faces.push([base + 3, base, base + 4]);
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ctl_pts.push(ControlPoint {
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uv: [1.0, 0.0],
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dir: [-1.0, 1.0, 1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [1.0, 1.0],
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dir: [-1.0, 1.0, -1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 1.0],
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dir: [-1.0, -1.0, -1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 0.0],
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dir: [-1.0, -1.0, 1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.5, 0.5],
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dir: [-1.0, 0.0, 0.0],
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});
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}
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// +y plane
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{
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let base = ctl_pts.len() as u32;
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faces.push([base, base + 1, base + 4]);
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faces.push([base + 1, base + 2, base + 4]);
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faces.push([base + 2, base + 3, base + 4]);
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faces.push([base + 3, base, base + 4]);
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ctl_pts.push(ControlPoint {
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uv: [0.0, 0.0],
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dir: [1.0, 1.0, 1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 1.0],
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dir: [1.0, 1.0, -1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 1.0],
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dir: [-1.0, 1.0, -1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 0.0],
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dir: [-1.0, 1.0, 1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 0.5],
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dir: [0.0, 1.0, 0.0],
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});
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}
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// -y plane
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{
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let base = ctl_pts.len() as u32;
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faces.push([base, base + 1, base + 4]);
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faces.push([base + 1, base + 2, base + 4]);
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faces.push([base + 2, base + 3, base + 4]);
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faces.push([base + 3, base, base + 4]);
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ctl_pts.push(ControlPoint {
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uv: [0.0, 0.0],
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dir: [-1.0, -1.0, 1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 1.0],
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dir: [-1.0, -1.0, -1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 1.0],
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dir: [1.0, -1.0, -1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 0.0],
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dir: [1.0, -1.0, 1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 0.5],
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dir: [0.0, -1.0, 0.0],
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});
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}
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// +z plane
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{
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let base = ctl_pts.len() as u32;
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faces.push([base, base + 1, base + 4]);
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faces.push([base + 1, base + 2, base + 4]);
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faces.push([base + 2, base + 3, base + 4]);
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faces.push([base + 3, base, base + 4]);
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ctl_pts.push(ControlPoint {
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uv: [0.0, 0.0],
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dir: [-1.0, 1.0, 1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 1.0],
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dir: [-1.0, -1.0, 1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [1.0, 1.0],
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dir: [1.0, -1.0, 1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [1.0, 0.0],
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dir: [1.0, 1.0, 1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.5, 0.5],
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dir: [0.0, 0.0, 1.0],
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});
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}
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// -z plane
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{
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let base = ctl_pts.len() as u32;
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faces.push([base, base + 1, base + 4]);
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faces.push([base + 1, base + 2, base + 4]);
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faces.push([base + 2, base + 3, base + 4]);
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faces.push([base + 3, base, base + 4]);
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ctl_pts.push(ControlPoint {
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uv: [1.0, 0.0],
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dir: [1.0, 1.0, -1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [1.0, 1.0],
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dir: [1.0, -1.0, -1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 1.0],
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dir: [-1.0, -1.0, -1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.0, 0.0],
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dir: [-1.0, 1.0, -1.0],
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});
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ctl_pts.push(ControlPoint {
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uv: [0.5, 0.5],
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dir: [0.0, 0.0, -1.0],
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});
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}
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for pt in ctl_pts {
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let p: Vec3 = pt.dir.into();
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let n: Vec3 = p.normalize();
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let t: Vec2 = pt.uv.into();
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vertices.push(Vertex {
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position: (p / 2.0).into(),
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normal: n.into(),
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tex_coord: t.into(),
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});
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}
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Mesh { faces, vertices }
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}
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fn main() {
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let mut cube = make_cube();
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let ret = bevy_mikktspace::generate_tangents(&mut cube);
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assert_eq!(true, ret);
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}
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