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fix normals for the gear teeth

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This commit is contained in:
numzero 2026-10-17 22:55:45 +03:00
parent 232720a78a
commit 4fad56a7d1
1 changed files with 85 additions and 25 deletions
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110
src/crown_gear.rs
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@ -23,7 +23,7 @@ impl CrownGear {
let outer_scale = self.outer_radius / self.pitch_radius;
let mut mesh = CpuMeshIndexed::new();
mesh.vertices.reserve_exact(4 * sides);
mesh.vertices.reserve_exact(8 * sides);
mesh.faces.reserve_exact(8 * sides);
for k in 0..sides {
let t = k as f32 / sides as f32;
@ -31,24 +31,22 @@ impl CrownGear {
let (s, c) = phi.sin_cos();
let tooth = t * teeth;
let y = self.profile.y_from_tooth(tooth);
mesh.vertices.push(Vertex {
position: vec3(
c * self.inner_radius,
s * self.inner_radius,
-self.base_thickness,
),
color,
normal: Vec3::ZERO, // FIXME calculate the normal
});
mesh.vertices.push(Vertex {
position: vec3(
c * self.outer_radius,
s * self.outer_radius,
-self.base_thickness,
),
color,
normal: Vec3::ZERO, // FIXME calculate the normal
});
let eps = 1e-3;
let dy_dt = teeth
* (self.profile.y_from_tooth(tooth + eps) - self.profile.y_from_tooth(tooth - eps))
/ (2.0 * eps);
let v_radial = vec3(c * self.pitch_radius, s * self.pitch_radius, y);
let v_tan = vec3(-2.0 * PI * s, 2.0 * PI * c, dy_dt / self.pitch_radius);
let n_top = v_radial.cross(v_tan).normalize();
let n_top = vec3(
s * dy_dt - 2.0 * PI * c * y,
-c * dy_dt - 2.0 * PI * s * y,
2.0 * PI * self.pitch_radius,
);
// top
mesh.vertices.push(Vertex {
position: vec3(
c * self.outer_radius,
@ -56,7 +54,7 @@ impl CrownGear {
outer_scale * y,
),
color,
normal: Vec3::ZERO, // FIXME calculate the normal
normal: n_top,
});
mesh.vertices.push(Vertex {
position: vec3(
@ -65,12 +63,74 @@ impl CrownGear {
inner_scale * y,
),
color,
normal: Vec3::ZERO, // FIXME calculate the normal
normal: n_top,
});
let base1 = 4 * k;
let base2 = 4 * ((k + 1) % sides);
for j1 in 0..4 {
let j2 = (j1 + 1) % 4;
// bottom
mesh.vertices.push(Vertex {
position: vec3(
c * self.inner_radius,
s * self.inner_radius,
-self.base_thickness,
),
color,
normal: vec3(0.0, 0.0, -1.0),
});
mesh.vertices.push(Vertex {
position: vec3(
c * self.outer_radius,
s * self.outer_radius,
-self.base_thickness,
),
color,
normal: vec3(0.0, 0.0, -1.0),
});
// inner
mesh.vertices.push(Vertex {
position: vec3(
c * self.inner_radius,
s * self.inner_radius,
inner_scale * y,
),
color,
normal: vec3(-c, -s, 0.0),
});
mesh.vertices.push(Vertex {
position: vec3(
c * self.inner_radius,
s * self.inner_radius,
-self.base_thickness,
),
color,
normal: vec3(-c, -s, 0.0),
});
// outer
mesh.vertices.push(Vertex {
position: vec3(
c * self.outer_radius,
s * self.outer_radius,
-self.base_thickness,
),
color,
normal: vec3(c, s, 0.0),
});
mesh.vertices.push(Vertex {
position: vec3(
c * self.outer_radius,
s * self.outer_radius,
outer_scale * y,
),
color,
normal: vec3(c, s, 0.0),
});
let base1 = 8 * k;
let base2 = 8 * ((k + 1) % sides);
for j in 0..4 {
let j1 = 2 * j;
let j2 = 2 * j + 1;
mesh.faces.push(
[base1 + j1, base2 + j1, base1 + j2].map(|index| index.try_into().unwrap()),
);