do basic cutting

src/bevel_gear.rs

@@ -1,8 +1,8 @@
-use std::f32::consts::PI;
+use std::f32::consts::{FRAC_PI_2, PI};
 
-use glam::{Mat3A, Vec2, Vec3, vec3};
+use glam::{Affine3A, FloatExt, Quat, Vec2, Vec3, Vec3Swizzles, vec3};
 
-use crate::{profile::Profile, render::mesh::MeshIndexed};
+use crate::{crown_gear::CrownGearDesc, profile::Profile, render::mesh::MeshIndexed};
 
 #[derive(Debug, Clone, Copy)]
 pub struct BevelGearDesc {
@@ -12,8 +12,8 @@ pub struct BevelGearDesc {
 }
 
 impl BevelGearDesc {
-	pub fn cutter(&self) -> crate::crown_gear::CrownGearDesc {
-		crate::crown_gear::CrownGearDesc {
+	pub fn cutter(&self) -> CrownGearDesc {
+		CrownGearDesc {
 			profile: Profile {
 				addendum: self.profile.dedendum,
 				dedendum: self.profile.addendum,
@@ -34,19 +34,17 @@ impl BevelGearDesc {
 
 #[derive(Debug, Clone)]
 pub struct BevelGearShape {
+	desc: BevelGearDesc,
 	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)
+		BevelGearShape {
+			desc: *desc,
+			points: vec![r; n_points],
+		}
 	}
 
 	pub fn to_points(&self) -> impl Iterator<Item = Vec2> {
@@ -56,6 +54,38 @@ impl BevelGearShape {
 			.enumerate()
 			.map(move |(k, r)| Vec2::from_angle(k as f32 * angle) * r)
 	}
+
+	pub fn cut(&mut self, offset_teeth: f32) {
+		let cutter = self.desc.cutter();
+		let crown_skip_teeth = cutter.pitch_radius.floor();
+		let crown_turns = (offset_teeth.fract_gl() + crown_skip_teeth) / (2. * cutter.pitch_radius);
+		let cutter_tfm = Affine3A::from_rotation_translation(
+			Quat::from_rotation_y(FRAC_PI_2 + self.desc.cone_halfangle)
+				* Quat::from_rotation_z(2. * PI * crown_turns),
+			vec3(0., 0., self.desc.pitch_distance()),
+		);
+		let z_proj = self.desc.pitch_distance();
+		let cutting_line = cutter.to_shape(0.375..0.725, 200);
+		let cutting_line: Vec<_> = cutting_line
+			.into_iter()
+			.map(|pt| {
+				let pt_3d = cutter_tfm.transform_point3(pt);
+				let pt_2d = -pt_3d.xy() * (z_proj / (z_proj - pt_3d.z));
+				pt_2d
+			})
+			.collect();
+		let len = self.points.len();
+		for (k, pt) in self.points.iter_mut().enumerate() {
+			let dir = Vec2::from_angle(
+				2.0 * PI * (k as f32 / len as f32 - offset_teeth / self.desc.teeth as f32),
+			);
+			for line in cutting_line.iter().zip(&cutting_line[1..]) {
+				if line.0.dot(dir.perp()) >= 0. && line.1.dot(dir.perp()) <= 0. {
+					*pt = pt.min(f32::min(line.0.length(), line.1.length()));
+				}
+			}
+		}
+	}
 }
 
 #[derive(Debug, Clone, Copy)]

src/lib.rs

@@ -65,7 +65,6 @@ pub struct Core {
 
 	mesh_pipeline: render::mesh::Pipeline,
 
-	mesh_gear: render::mesh::GpuMeshIndexed,
 	mesh_cutter: render::mesh::GpuMeshIndexed,
 
 	params_gear: render::mesh::GpuParams,
@@ -118,18 +117,7 @@ impl Core {
 			teeth: args.tooth,
 			cone_halfangle: args.cone_halfangle,
 		};
-		let bevel_gear_shape = bevel_gear::BevelGearShape::new_blank(&bevel_gear_desc, 60);
-		let bevel_gear_mesh = bevel_gear::make_mesh(
-			&bevel_gear_desc,
-			&bevel_gear::BevelGearVisual {
-				pad_in: 4.,
-				pad_out: 0.,
-			},
-			&bevel_gear_shape,
-		)
-		.to_mesh()
-		.to_standard_mesh()
-		.into_indexed();
+		let bevel_gear_shape = bevel_gear::BevelGearShape::new_blank(&bevel_gear_desc, 600);
 
 		let crown_gear_desc = bevel_gear_desc.cutter();
 		let crown_gear_mesh = crown_gear::make_mesh_simple(
@@ -146,7 +134,6 @@ impl Core {
 		.into_indexed();
 
 		let mesh_cutter = render::mesh::GpuMeshIndexed::new(&device, &crown_gear_mesh);
-		let mesh_gear = render::mesh::GpuMeshIndexed::new(&device, &bevel_gear_mesh);
 
 		let params_gear = GpuParams::new(&device, &mesh_pipeline);
 		let params_cutter = GpuParams::new(&device, &mesh_pipeline);
@@ -159,7 +146,6 @@ impl Core {
 			surface,
 			depth,
 			mesh_pipeline,
-			mesh_gear,
 			mesh_cutter,
 			params_gear,
 			params_cutter,
@@ -199,7 +185,7 @@ impl Core {
 		);
 
 		let turn_teeth = self.t;
-		let bevel_turns = -turn_teeth / self.bevel_gear_desc.teeth as f32;
+		let bevel_turns = 0.5 - turn_teeth / self.bevel_gear_desc.teeth as f32;
 		let crown_skip_teeth = self.crown_gear_desc.pitch_radius.floor();
 		let crown_turns =
 			(turn_teeth.fract_gl() + crown_skip_teeth) / (2. * self.crown_gear_desc.pitch_radius);
@@ -226,6 +212,19 @@ impl Core {
 			},
 		);
 
+		let bevel_gear_mesh = bevel_gear::make_mesh(
+			&self.bevel_gear_desc,
+			&bevel_gear::BevelGearVisual {
+				pad_in: 4.,
+				pad_out: 0.,
+			},
+			&self.bevel_gear_shape,
+		)
+		.to_mesh()
+		.to_standard_mesh()
+		.into_indexed();
+		let mesh_gear = render::mesh::GpuMeshIndexed::new(&self.device, &bevel_gear_mesh);
+
 		let view = output.create_view(&wgpu::TextureViewDescriptor::default());
 		let depth_view = self
 			.depth
@@ -255,8 +254,7 @@ impl Core {
 		});
 		self.mesh_cutter
 			.render(&mut pass, &self.mesh_pipeline, &self.params_cutter);
-		self.mesh_gear
-			.render(&mut pass, &self.mesh_pipeline, &self.params_gear);
+		mesh_gear.render(&mut pass, &self.mesh_pipeline, &self.params_gear);
 		drop(pass);
 		self.queue.submit(std::iter::once(encoder.finish()));
 	}
@@ -304,6 +302,7 @@ impl Core {
 	///
 	/// [`Self::configure`] must be called at least once before this.
 	pub fn redraw(&mut self, args: &RedrawArgs) {
+		self.bevel_gear_shape.cut(self.t);
 		let output = self.surface.get_current_texture().unwrap();
 		self.render(&output.texture, args);
 		output.present();