Make bevy_mikktspace optional (#21390)

# Objective

- allow users to cut unneeded deps

## Solution

- feature gate

## Testing

- clearcoat example uses generated tangents, still works.

Author: atlv24

Cargo.toml

@@ -149,6 +149,7 @@ default = [
   "bevy_scene",
   "bevy_image",
   "bevy_mesh",
+  "bevy_mikktspace",
   "bevy_camera",
   "bevy_light",
   "bevy_shader",
@@ -272,6 +273,9 @@ bevy_image = ["bevy_internal/bevy_image"]
 # Provides a mesh format and some primitive meshing routines.
 bevy_mesh = ["bevy_internal/bevy_mesh"]
 
+# Provides vertex tangent generation for use with bevy_mesh.
+bevy_mikktspace = ["bevy_internal/bevy_mikktspace"]
+
 # Provides camera and visibility types, as well as culling primitives.
 bevy_camera = ["bevy_internal/bevy_camera"]
 

crates/bevy_internal/Cargo.toml

@@ -222,6 +222,7 @@ bevy_text = [
 bevy_ui = ["dep:bevy_ui", "bevy_text", "bevy_sprite"]
 bevy_mesh = ["dep:bevy_mesh", "bevy_image"]
 bevy_animation = ["dep:bevy_animation", "bevy_mesh"]
+bevy_mikktspace = ["bevy_mesh?/bevy_mikktspace"]
 bevy_window = ["dep:bevy_window", "dep:bevy_a11y", "bevy_image"]
 bevy_winit = ["dep:bevy_winit", "bevy_window"]
 bevy_camera = ["dep:bevy_camera", "bevy_mesh", "bevy_window"]

crates/bevy_mesh/Cargo.toml

@@ -17,7 +17,7 @@ bevy_math = { path = "../bevy_math", version = "0.18.0-dev" }
 bevy_reflect = { path = "../bevy_reflect", version = "0.18.0-dev" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.18.0-dev" }
 bevy_transform = { path = "../bevy_transform", version = "0.18.0-dev" }
-bevy_mikktspace = { version = "0.17.0-dev" }
+bevy_mikktspace = { version = "0.17.0-dev", optional = true }
 bevy_derive = { path = "../bevy_derive", version = "0.18.0-dev" }
 bevy_platform = { path = "../bevy_platform", version = "0.18.0-dev", default-features = false, features = [
   "std",

crates/bevy_mesh/src/lib.rs

@@ -7,6 +7,7 @@ mod components;
 mod conversions;
 mod index;
 mod mesh;
+#[cfg(feature = "bevy_mikktspace")]
 mod mikktspace;
 #[cfg(feature = "morph")]
 pub mod morph;
@@ -20,6 +21,7 @@ use bitflags::bitflags;
 pub use components::*;
 pub use index::*;
 pub use mesh::*;
+#[cfg(feature = "bevy_mikktspace")]
 pub use mikktspace::*;
 pub use primitives::*;
 pub use vertex::*;

crates/bevy_mesh/src/mesh.rs

@@ -2,10 +2,10 @@ use bevy_transform::components::Transform;
 pub use wgpu_types::PrimitiveTopology;
 
 use super::{
-    generate_tangents_for_mesh, scale_normal, triangle_area_normal, triangle_normal, FourIterators,
-    GenerateTangentsError, Indices, MeshAttributeData, MeshTrianglesError, MeshVertexAttribute,
-    MeshVertexAttributeId, MeshVertexBufferLayout, MeshVertexBufferLayoutRef,
-    MeshVertexBufferLayouts, MeshWindingInvertError, VertexAttributeValues, VertexBufferLayout,
+    triangle_area_normal, triangle_normal, FourIterators, Indices, MeshAttributeData,
+    MeshTrianglesError, MeshVertexAttribute, MeshVertexAttributeId, MeshVertexBufferLayout,
+    MeshVertexBufferLayoutRef, MeshVertexBufferLayouts, MeshWindingInvertError,
+    VertexAttributeValues, VertexBufferLayout,
 };
 #[cfg(feature = "serialize")]
 use crate::SerializedMeshAttributeData;
@@ -942,8 +942,9 @@ impl Mesh {
     ///
     /// Sets the [`Mesh::ATTRIBUTE_TANGENT`] attribute if successful.
     /// Requires a [`PrimitiveTopology::TriangleList`] topology and the [`Mesh::ATTRIBUTE_POSITION`], [`Mesh::ATTRIBUTE_NORMAL`] and [`Mesh::ATTRIBUTE_UV_0`] attributes set.
-    pub fn generate_tangents(&mut self) -> Result<(), GenerateTangentsError> {
-        let tangents = generate_tangents_for_mesh(self)?;
+    #[cfg(feature = "bevy_mikktspace")]
+    pub fn generate_tangents(&mut self) -> Result<(), super::GenerateTangentsError> {
+        let tangents = super::generate_tangents_for_mesh(self)?;
         self.insert_attribute(Mesh::ATTRIBUTE_TANGENT, tangents);
         Ok(())
     }
@@ -955,7 +956,8 @@ impl Mesh {
     /// (Alternatively, you can use [`Mesh::generate_tangents`] to mutate an existing mesh in-place)
     ///
     /// Requires a [`PrimitiveTopology::TriangleList`] topology and the [`Mesh::ATTRIBUTE_POSITION`], [`Mesh::ATTRIBUTE_NORMAL`] and [`Mesh::ATTRIBUTE_UV_0`] attributes set.
-    pub fn with_generated_tangents(mut self) -> Result<Mesh, GenerateTangentsError> {
+    #[cfg(feature = "bevy_mikktspace")]
+    pub fn with_generated_tangents(mut self) -> Result<Mesh, super::GenerateTangentsError> {
         self.generate_tangents()?;
         Ok(self)
     }
@@ -1414,6 +1416,21 @@ impl Mesh {
     }
 }
 
+/// Correctly scales and renormalizes an already normalized `normal` by the scale determined by its reciprocal `scale_recip`
+pub(crate) fn scale_normal(normal: Vec3, scale_recip: Vec3) -> Vec3 {
+    // This is basically just `normal * scale_recip` but with the added rule that `0. * anything == 0.`
+    // This is necessary because components of `scale_recip` may be infinities, which do not multiply to zero
+    let n = Vec3::select(normal.cmpeq(Vec3::ZERO), Vec3::ZERO, normal * scale_recip);
+
+    // If n is finite, no component of `scale_recip` was infinite or the normal was perpendicular to the scale
+    // else the scale had at least one zero-component and the normal needs to point along the direction of that component
+    if n.is_finite() {
+        n.normalize_or_zero()
+    } else {
+        Vec3::select(n.abs().cmpeq(Vec3::INFINITY), n.signum(), Vec3::ZERO).normalize()
+    }
+}
+
 impl core::ops::Mul<Mesh> for Transform {
     type Output = Mesh;
 

crates/bevy_mesh/src/mikktspace.rs

@@ -1,5 +1,4 @@
 use super::{Indices, Mesh, VertexAttributeValues};
-use bevy_math::Vec3;
 use thiserror::Error;
 use wgpu_types::{PrimitiveTopology, VertexFormat};
 
@@ -127,18 +126,3 @@ pub(crate) fn generate_tangents_for_mesh(
 
     Ok(mikktspace_mesh.tangents)
 }
-
-/// Correctly scales and renormalizes an already normalized `normal` by the scale determined by its reciprocal `scale_recip`
-pub(crate) fn scale_normal(normal: Vec3, scale_recip: Vec3) -> Vec3 {
-    // This is basically just `normal * scale_recip` but with the added rule that `0. * anything == 0.`
-    // This is necessary because components of `scale_recip` may be infinities, which do not multiply to zero
-    let n = Vec3::select(normal.cmpeq(Vec3::ZERO), Vec3::ZERO, normal * scale_recip);
-
-    // If n is finite, no component of `scale_recip` was infinite or the normal was perpendicular to the scale
-    // else the scale had at least one zero-component and the normal needs to point along the direction of that component
-    if n.is_finite() {
-        n.normalize_or_zero()
-    } else {
-        Vec3::select(n.abs().cmpeq(Vec3::INFINITY), n.signum(), Vec3::ZERO).normalize()
-    }
-}

docs/cargo_features.md

@@ -29,6 +29,7 @@ The default feature set enables most of the expected features of a game engine,
 |bevy_log|Enable integration with `tracing` and `log`|
 |bevy_mesh|Provides a mesh format and some primitive meshing routines.|
 |bevy_mesh_picking_backend|Provides an implementation for picking meshes|
+|bevy_mikktspace|Provides vertex tangent generation for use with bevy_mesh.|
 |bevy_pbr|Adds PBR rendering|
 |bevy_picking|Provides picking functionality|
 |bevy_post_process|Provides post process effects such as depth of field, bloom, chromatic aberration.|