Render both stalk and cap as cynlinders.

src/main.rs

@@ -5,7 +5,6 @@ use self::mushroom::Mushroom;
 use clap::Parser;
 use std::fs::OpenOptions;
 
-#[macro_use]
 extern crate approx;
 
 // TODO: Investigate https://github.com/virtualritz/polyhedron-ops.
@@ -80,7 +79,8 @@ fn main() {
     let mushroom = mushroom_from_args(&args);
 
     // Render the mushroom.
-    let mesh = render::cylinder(mushroom.stalk_h, mushroom.stalk_d, 128);
+    // let mesh = render::cylinder(mushroom.stalk_h, mushroom.stalk_d, 128);
+    let mesh = render::mushroom(&mushroom);
 
     // Save output to file.
     let mut file = OpenOptions::new()
@@ -91,8 +91,7 @@ fn main() {
         .unwrap();
     stl_io::write_stl(&mut file, mesh.iter()).unwrap();
 
-    println!("From: {:?}", mushroom);
-    println!("Generated:\n{:?}", mesh);
+    println!("Generated from: {:?}", mushroom);
 }
 
 #[cfg(test)]

src/render.rs

@@ -1,5 +1,7 @@
 use stl_io::{self, Normal, Triangle, Vertex};
 
+use crate::mushroom::Mushroom;
+
 fn new_triangle(p1: &Vertex, p2: &Vertex, p3: &Vertex) -> stl_io::Triangle {
     // Set Vector U to (Triangle.p2 minus Triangle.p1)
     // Set Vector V to (Triangle.p3 minus Triangle.p1)
@@ -78,17 +80,40 @@ fn tube_top(center: &Vertex, edge: &Vec<Vertex>) -> Vec<Triangle> {
     return tube_base(&center, &edge);
 }
 
-pub fn cylinder(height: f32, radius: f32, steps: u32) -> Vec<Triangle> {
-    let base_center = Vertex::new([0.0, 0.0, 0.0]);
-    let base_edge = vertexes_on_circle(&base_center, radius, steps);
-    let top_center = Vertex::new([0.0, 0.0, height]);
-    let top_edge = vertexes_on_circle(&top_center, radius, steps);
+pub fn mushroom(mushroom: &Mushroom) -> Vec<Triangle> {
+    // Max size of any flat surface in mm.
+    let resolution: f32 = 1.0;
+
+    // We always use the same number of diameter steps to ensure the number of circular vertices doesn't change,
+    // which might create small breaks in our model.
+    let diameter_steps = std::cmp::max(
+        (mushroom.cap_d * std::f32::consts::TAU * resolution) as u32,
+        64,
+    );
+
+    let stalk_base_center = Vertex::new([0.0, 0.0, 0.0]);
+    let stalk_base_edge = vertexes_on_circle(&stalk_base_center, mushroom.stalk_d, diameter_steps);
+    let stalk_top_center = Vertex::new([
+        stalk_base_center[0],
+        stalk_base_center[1],
+        stalk_base_center[2] + mushroom.stalk_h,
+    ]);
+    let stalk_top_edge = vertexes_on_circle(&stalk_top_center, mushroom.stalk_d, diameter_steps);
+    let cap_base_edge = vertexes_on_circle(&stalk_top_center, mushroom.cap_d, diameter_steps);
+    let cap_top_center = Vertex::new([
+        stalk_top_center[0],
+        stalk_top_center[1],
+        stalk_top_center[2] + mushroom.cap_h,
+    ]);
+    let cap_top_edge = vertexes_on_circle(&cap_top_center, mushroom.cap_d, diameter_steps);
 
     let mut result = Vec::new();
 
-    result.append(&mut tube_base(&base_center, &base_edge));
-    result.append(&mut tube_sides(&base_edge, &top_edge));
-    result.append(&mut tube_top(&top_center, &top_edge));
+    result.append(&mut tube_base(&stalk_base_center, &stalk_base_edge));
+    result.append(&mut tube_sides(&stalk_base_edge, &stalk_top_edge));
+    result.append(&mut tube_sides(&stalk_top_edge, &cap_base_edge));
+    result.append(&mut tube_sides(&cap_base_edge, &cap_top_edge));
+    result.append(&mut tube_top(&cap_top_center, &cap_top_edge));
 
     return result;
 }