WIP: Koch’s Snowflake

Cargo.lock

@@ -381,6 +381,12 @@ version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d8b14ccef22fc6f5a8f4d7d768562a182c04ce9a3b3157b91390b52ddfdf1a76"
 
+[[package]]
+name = "either"
+version = "1.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9e5e8f6c15a24b9a3ee5efec809ccd006d3b30e8b3bb63c39af737c7f87daa1d"
+
 [[package]]
 name = "equivalent"
 version = "1.0.2"
@@ -629,6 +635,7 @@ version = "0.1.0"
 dependencies = [
  "bytemuck",
  "glam",
+ "itertools",
  "pollster",
  "wgpu",
  "winit",
@@ -656,6 +663,15 @@ dependencies = [
  "hashbrown 0.16.1",
 ]
 
+[[package]]
+name = "itertools"
+version = "0.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b4baf93f58d4425749ca49a51c50ebab072c5df6994d08fed93541c331481dc"
+dependencies = [
+ "either",
+]
+
 [[package]]
 name = "jni"
 version = "0.21.1"

Cargo.toml

@@ -20,6 +20,7 @@ opt-level = 3
 [dependencies]
 bytemuck = { version = "1.25.2", features = ["derive"] }
 glam = { version = "0.30.9", features = ["bytemuck"] }
+itertools = "0.15.0"
 pollster = "0.4.0"
 wgpu = "27.0.1"
 winit = "0.30.12"

src/mesh.rs

@@ -1,6 +1,7 @@
-use std::f32::consts::PI;
+use std::f32::consts::{FRAC_PI_3, PI};
 
 use glam::{Mat2, Vec3, Vec3Swizzles, vec2, vec3};
+use itertools::Itertools;
 
 pub type Face = [usize; 3];
 
@@ -93,16 +94,67 @@ pub fn shell(shape: &crate::ShapeArgs) -> Mesh {
 }
 
 pub fn solid(shape: &crate::ShapeArgs) -> Mesh {
-	let sides = shape.sides as usize;
+	let r = shape.base_diameter / 2.0;
 
-	let mut mesh = shell(shape);
+	let mut mesh = Mesh::default();
 
-	let mut bottom = disc_faces(0, sides);
+	let mut pts = Vec::new();
-	flip_faces(&mut bottom);
+	for a in 0..3 {
-	mesh.faces.extend(bottom);
+		let angle = 2.0 * a as f32 * FRAC_PI_3;
-
+		let (y, x) = angle.sin_cos();
-	let top = disc_faces(mesh.vertices.len() - sides, sides);
+		pts.push(vec2(x, y));
-	mesh.faces.extend(top);
+	}
+	mesh.vertices
+		.extend(pts.iter().map(|pt| r * vec3(pt.x, pt.y, 0.0)));
+	mesh.faces.push([0, 2, 1]);
+	let n_layers = 4;
+	for layer in 1..n_layers {
+		let mut new_pts = Vec::new();
+		let z0 = 1.0 - 3.0f32.powf(-(layer - 1) as f32);
+		let z = 1.0 - 3.0f32.powf(-layer as f32);
+		for [a, b] in pts.iter().copied().circular_array_windows() {
+			let along = b - a;
+			let across = -along.perp();
+			let c = (2. * a + b) / 3.;
+			let d = (a + 2. * b) / 3.;
+			let mid = (a + b) / 2.;
+			let e = mid + across * (1.0f32 / 12.).sqrt();
+			new_pts.push(a);
+			new_pts.push(c);
+			new_pts.push(e);
+			new_pts.push(d);
+			let base = mesh.vertices.len();
+			mesh.vertices
+				.extend([a, mid, b].map(|pt| r * vec3(pt.x, pt.y, z0)));
+			mesh.vertices
+				.extend([a, c, e, d, b].map(|pt| r * vec3(pt.x, pt.y, z)));
+			mesh.faces.extend(
+				[
+					[0, 4, 3],
+					[0, 1, 4],
+					[1, 5, 4],
+					[1, 6, 5],
+					[1, 2, 6],
+					[2, 7, 6],
+				]
+				.map(|face| face.map(|index| base + index)),
+			);
+		}
+		pts = new_pts;
+	}
+	{
+		let z0 = 1.0 - 3.0f32.powf(-(n_layers - 1) as f32);
+		let z = 1.0 - 3.0f32.powf(-n_layers as f32);
+		for [a, b] in pts.iter().copied().circular_array_windows() {
+			let base = mesh.vertices.len();
+			mesh.vertices
+				.extend([a, b].map(|pt| r * vec3(pt.x, pt.y, z0)));
+			mesh.vertices
+				.extend([a, b].map(|pt| r * vec3(pt.x, pt.y, z)));
+			mesh.faces
+				.extend([[0, 3, 2], [0, 1, 3]].map(|face| face.map(|index| base + index)));
+		}
+	}
 
 	mesh
 }
@@ -143,9 +195,5 @@ pub fn cup(shape: &crate::ShapeArgs) -> Mesh {
 }
 
 pub fn make(shape: &crate::ShapeArgs) -> Mesh {
-	match shape.mode {
+	solid(shape)
-		crate::Mode::Solid => solid(shape),
-		crate::Mode::Shell => cup(shape),
-		crate::Mode::Mesh => Default::default(), // TODO implement
-	}
 }

ui/src/main_window.ui

@@ -221,13 +221,13 @@
            <double>4.000000000000000</double>
           </property>
           <property name="maximum">
-           <double>100.000000000000000</double>
+           <double>200.000000000000000</double>
           </property>
           <property name="stepType">
            <enum>QAbstractSpinBox::StepType::AdaptiveDecimalStepType</enum>
           </property>
           <property name="value">
-           <double>36.000000000000000</double>
+           <double>100.000000000000000</double>
           </property>
          </widget>
         </item>