gl_utils/mesh/
mod.rs

1//! Mesh generation utilities.
2
3use std::path::Path;
4use bytemuck;
5use derive_more::{From, TryInto};
6use gltf;
7use strum;
8use crate::{math, math::geometry, util, vertex};
9
10pub mod capsule;
11pub mod cube;
12pub mod cylinder;
13pub mod grid;
14pub mod hemisphere;
15pub mod sphere;
16
17#[derive(Clone, Debug, PartialEq, From, TryInto)]
18pub enum Mesh {
19  Lines3d (Lines3d)
20}
21
22/// Raw data defining a wireframe mesh
23#[derive(Clone, Debug, PartialEq, From)]
24pub struct Lines3d {
25  pub vertices : Vec <vertex::Vert3dInstanced>,
26  pub indices  : Vec <u32>
27}
28
29impl Mesh {
30  /// Load a GLTF file containing a single mesh
31  pub fn load_gltf <P : AsRef <Path>> (path : P) -> Self {
32    let (document, buffers, _images) = gltf::import (path).unwrap();
33    let mut meshes = document.meshes();
34    let mesh = meshes.next().unwrap();
35    debug_assert!(meshes.peekable().next().is_none());
36    let mut primitives = mesh.primitives();
37    let primitive = primitives.next().unwrap();
38    debug_assert!(primitives.peekable().next().is_none());
39    let reader = primitive.reader (|buffer| Some (&buffers[buffer.index()]));
40    let vertices = reader.read_positions().unwrap()
41      .map (|inst_position| vertex::Vert3dInstanced { inst_position }).collect();
42    let indices  = reader.read_indices().unwrap().into_u32().collect();
43    Lines3d { vertices, indices }.into()
44  }
45
46  /// Write mesh to an embedded `.gltf` file
47  pub fn write_gltf <P : AsRef <Path>> (&self, path : P) {
48    fn bounding_coords (points: &[vertex::Vert3dInstanced])
49      -> ([f32; 3], [f32; 3])
50    {
51      let mut min = [f32::MAX, f32::MAX, f32::MAX];
52      let mut max = [f32::MIN, f32::MIN, f32::MIN];
53      for point in points {
54        let p = point.inst_position;
55        for i in 0..3 {
56          min[i] = f32::min (min[i], p[i]);
57          max[i] = f32::max (max[i], p[i]);
58        }
59      }
60      (min, max)
61    }
62    let (vertices, indices) = match self {
63      Mesh::Lines3d (Lines3d { vertices, indices }) => (vertices, indices)
64    };
65    let (min, max)        = bounding_coords (&vertices[..]);
66    let vertices_bytes    = bytemuck::cast_slice (vertices);
67    let indices_bytes     = bytemuck::cast_slice (indices);
68    let (buffer, views)   =
69      util::gltf::json_buffer_views (0, &[vertices_bytes, indices_bytes]);
70    let position_accessor = util::gltf::json_accessor (0, vertices.len() as u32,
71      gltf::json::accessor::Type::Vec3,
72      gltf::json::accessor::ComponentType::F32, Some ([min, max]));
73    let index_accessor    = util::gltf::json_accessor (1, indices.len() as u32,
74      gltf::json::accessor::Type::Scalar,
75      gltf::json::accessor::ComponentType::U32, None);
76    let lines_primitive   = util::gltf::json_primitive (
77      gltf::json::mesh::Semantic::Positions, gltf::json::mesh::Mode::Lines, 1);
78    let mesh              = util::gltf::json_mesh (vec![lines_primitive]);
79    let node              = util::gltf::json_node (0);
80    let root              = util::gltf::json_root (
81      vec![node], vec![mesh], vec![buffer], views,
82      vec![position_accessor, index_accessor]);
83    let writer            = std::fs::File::create (path).unwrap();
84    gltf::json::serialize::to_writer_pretty (writer, &root).unwrap();
85  }
86}
87
88impl Lines3d {
89  pub const fn empty() -> Self {
90    Lines3d { vertices: vec![], indices: vec![] }
91  }
92}
93
94impl From <geometry::Aabb3 <f32>> for Lines3d {
95  fn from (aabb : geometry::Aabb3 <f32>) -> Self {
96    use strum::IntoEnumIterator;
97    let vertices = math::Octant::iter().map (|octant| vertex::Vert3dInstanced {
98      inst_position: aabb.corner (octant).0.into_array()
99    }).collect();
100    let indices  = vec![
101      0, 1, 0, 2, 0, 4,
102      7, 6, 7, 5, 7, 3,
103      1, 3, 1, 5,
104      2, 3, 2, 6,
105      4, 5, 4, 6
106    ];
107    Lines3d { vertices, indices }
108  }
109}
gl_utils/mesh/mod.rs

gl_utils/mesh/
mod.rs
