65 lines
1.8 KiB
Rust
65 lines
1.8 KiB
Rust
use std::f32::consts::PI;
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use glam::{Mat2, Vec3, vec2, vec3};
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pub struct Mesh {
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pub vertices: Vec<Vec3>,
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pub faces: Vec<[usize; 3]>,
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}
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pub fn shell(shape: &crate::ShapeArgs) -> Mesh {
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let mut vertices = Vec::<Vec3>::new();
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let mut faces = Vec::<[usize; 3]>::new();
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let sides = shape.sides as usize;
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let layers = (shape.layers_up + shape.layers_down) as usize;
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let base_layer = shape.layers_down;
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let diameter = shape.base_diameter;
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let radius = diameter / 2.;
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let height = shape.height;
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let bottom_angle = (PI / sides as f32) * -(base_layer as f32);
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let top_angle = (PI / sides as f32) * (layers as f32 - base_layer as f32);
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let bottom_y = radius * bottom_angle.tan();
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let top_y = radius * top_angle.tan();
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let incline = height / (top_y - bottom_y);
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let elevation = -height / 2. - incline * bottom_y;
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for layer in 0..=layers {
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let angle = (PI / sides as f32) * (layer as f32 - base_layer as f32);
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let x = radius;
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let y = angle.tan() * x;
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let z = elevation + incline * y;
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for side in 0..sides {
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let angle = (2. * PI / sides as f32) * side as f32;
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let rot = Mat2::from_angle(angle);
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let xy = rot * vec2(x, y);
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let v = vec3(xy.x, xy.y, z);
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vertices.push(v);
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}
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}
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for layer in 0..layers {
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let base = sides * layer;
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for side in 0..sides {
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let index = |layer, offset| base + sides * layer + (side + offset) % sides;
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faces.push([index(0, 0), index(0, 1), index(1, 0)]);
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faces.push([index(0, 1), index(1, 1), index(1, 0)]);
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}
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}
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Mesh { vertices, faces }
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}
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pub fn solid(shape: &crate::ShapeArgs) -> Mesh {
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let mut mesh = shell(shape);
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let sides = shape.sides as usize;
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for side in 0..(sides - 2) {
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mesh.faces.push([sides - 1, side + 1, side]);
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}
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let base = mesh.vertices.len() - sides;
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for side in 0..(sides - 2) {
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mesh.faces
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.push([base + sides - 1, base + side, base + side + 1]);
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}
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mesh
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}
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