add a bevel gear blank

src/bevel_gear.rs

@@ -0,0 +1,110 @@
+use std::f32::consts::PI;
+
+use glam::{Mat3A, Vec2, Vec3, vec3};
+
+use crate::{profile::Profile, render::mesh::MeshIndexed};
+
+#[derive(Debug, Clone, Copy)]
+pub struct BevelGearDesc {
+	pub profile: Profile,
+	pub teeth: u32,
+	pub cone_halfangle: f32,
+}
+
+impl BevelGearDesc {
+	pub fn cutter(&self) -> crate::crown_gear::CrownGearDesc {
+		crate::crown_gear::CrownGearDesc {
+			profile: Profile {
+				addendum: self.profile.dedendum,
+				dedendum: self.profile.addendum,
+				pressure_angle: self.profile.pressure_angle,
+			},
+			pitch_radius: self.pitch_radius() / self.cone_halfangle.sin(),
+		}
+	}
+
+	fn pitch_radius(&self) -> f32 {
+		0.5 * self.teeth as f32
+	}
+
+	fn pitch_distance(&self) -> f32 {
+		self.pitch_radius() / self.cone_halfangle.tan()
+	}
+}
+
+#[derive(Debug, Clone)]
+pub struct BevelGearShape {
+	points: Vec<f32>,
+}
+
+impl BevelGearShape {
+	fn new_raw(r: f32, n_points: usize) -> Self {
+		BevelGearShape {
+			points: vec![r; n_points],
+		}
+	}
+
+	pub fn new_blank(desc: &BevelGearDesc, n_points: usize) -> Self {
+		let r = 0.5 * desc.teeth as f32 + desc.profile.addendum + 0.1;
+		Self::new_raw(r, n_points)
+	}
+
+	pub fn to_points(&self) -> impl Iterator<Item = Vec2> {
+		let angle = 2.0 * PI / self.points.len() as f32;
+		self.points
+			.iter()
+			.enumerate()
+			.map(move |(k, r)| Vec2::from_angle(k as f32 * angle) * r)
+	}
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum BevelGearCap {
+	Flat,
+	Conical,
+	Spherical,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct BevelGearVisual {
+	pub inner_distance: f32,
+	pub outer_distance: f32,
+}
+
+pub fn make_mesh(
+	desc: &BevelGearDesc,
+	visual: &BevelGearVisual,
+	shape: &BevelGearShape,
+) -> MeshIndexed<Vec3> {
+	let inner_scale = visual.inner_distance / desc.pitch_distance();
+	let outer_scale = visual.outer_distance / desc.pitch_distance();
+
+	let sides = shape.points.len();
+	let mut mesh = MeshIndexed::new();
+	mesh.vertices.reserve_exact(2 * sides + 2);
+	mesh.faces.reserve_exact(4 * sides);
+	for pt in shape.to_points() {
+		let pt = vec3(pt.x, pt.y, desc.pitch_distance());
+		mesh.vertices.extend([inner_scale * pt, outer_scale * pt]);
+	}
+	let caps = mesh.vertices.len();
+	mesh.vertices.extend([
+		vec3(0., 0., visual.inner_distance),
+		vec3(0., 0., visual.outer_distance),
+	]);
+	for k in 0..sides {
+		let base1 = 2 * k;
+		let base2 = 2 * ((k + 1) % sides);
+		mesh.faces.extend(
+			[
+				[base1, caps, base2],
+				[base1, base2, base1 + 1],
+				[base2 + 1, base1 + 1, base2],
+				[base2 + 1, caps + 1, base1 + 1],
+			]
+			.map(|face| face.map(|index| u16::try_from(index).unwrap())),
+		);
+	}
+
+	mesh
+}

src/lib.rs

@@ -2,6 +2,7 @@ use std::error::Error;
 
 use glam::{Mat4, UVec2, Vec3, Vec4, vec3, vec4};
 
+mod bevel_gear;
 mod camera;
 mod crown_gear;
 mod profile;
@@ -80,6 +81,7 @@ impl Core {
 
 		let depth = Self::create_depth_buffer(&device, pixel_size);
 		let mesh_pipeline = render::mesh::Pipeline::new(&device);
+
 		let crown_gear_mesh = crown_gear::make_mesh_simple(
 			&crown_gear::CrownGearDesc {
 				profile: Default::default(),
@@ -95,7 +97,25 @@ impl Core {
 		.to_mesh()
 		.to_standard_mesh(vec3(0.5, 0.5, 0.5))
 		.into_indexed();
-		let mesh_gray = render::mesh::GpuMeshIndexed::new(&device, &crown_gear_mesh);
+
+		let bevel_gear_desc = bevel_gear::BevelGearDesc {
+			profile: Default::default(),
+			teeth: 24,
+			cone_halfangle: 0.5,
+		};
+		let bevel_gear_mesh = bevel_gear::make_mesh(
+			&bevel_gear_desc,
+			&bevel_gear::BevelGearVisual {
+				inner_distance: 8.0,
+				outer_distance: 12.0,
+			},
+			&bevel_gear::BevelGearShape::new_blank(&bevel_gear_desc, 60),
+		)
+		.to_mesh()
+		.to_standard_mesh(vec3(0.5, 0.5, 0.5))
+		.into_indexed();
+
+		let mesh_gray = render::mesh::GpuMeshIndexed::new(&device, &bevel_gear_mesh);
 
 		Self::configure_surface(&surface, &device, pixel_size);