genmesh/
cube.rs

1use super::generators::{IndexedPolygon, SharedVertex};
2use super::{MapVertex, Quad};
3use std::ops::Range;
4use {Normal, Position, Vertex};
5
6/// A perfect cube, centered at (0, 0, 0) with each face starting at 1/-1 away from the origin
7#[derive(Clone)]
8pub struct Cube {
9    range: Range<usize>,
10}
11
12impl Cube {
13    /// create a new cube generator
14    pub fn new() -> Self {
15        Cube { range: 0..6 }
16    }
17
18    fn vert(&self, idx: usize) -> Position {
19        let x = if idx & 4 == 4 { 1. } else { -1. };
20        let y = if idx & 2 == 2 { 1. } else { -1. };
21        let z = if idx & 1 == 1 { 1. } else { -1. };
22        [x, y, z].into()
23    }
24
25    fn face_indexed(&self, idx: usize) -> (Normal, Quad<usize>) {
26        match idx {
27            0 => ([1., 0., 0.].into(), Quad::new(0b110, 0b111, 0b101, 0b100)),
28            1 => ([-1., 0., 0.].into(), Quad::new(0b000, 0b001, 0b011, 0b010)),
29            2 => ([0., 1., 0.].into(), Quad::new(0b011, 0b111, 0b110, 0b010)),
30            3 => ([0., -1., 0.].into(), Quad::new(0b100, 0b101, 0b001, 0b000)),
31            4 => ([0., 0., 1.].into(), Quad::new(0b101, 0b111, 0b011, 0b001)),
32            5 => ([0., 0., -1.].into(), Quad::new(0b000, 0b010, 0b110, 0b100)),
33            idx => panic!("{} face is higher then 6", idx),
34        }
35    }
36
37    fn face(&self, idx: usize) -> Quad<Vertex> {
38        let (no, quad) = self.face_indexed(idx);
39        quad.map_vertex(|i| Vertex {
40            pos: self.vert(i),
41            normal: no,
42        })
43    }
44}
45
46impl Iterator for Cube {
47    type Item = Quad<Vertex>;
48
49    fn next(&mut self) -> Option<Quad<Vertex>> {
50        self.range.next().map(|idx| self.face(idx))
51    }
52
53    fn size_hint(&self) -> (usize, Option<usize>) {
54        self.range.size_hint()
55    }
56}
57
58impl SharedVertex<Vertex> for Cube {
59    fn shared_vertex(&self, idx: usize) -> Vertex {
60        let (no, quad) = self.face_indexed(idx / 4);
61        let vid = match idx % 4 {
62            0 => quad.x,
63            1 => quad.y,
64            2 => quad.z,
65            3 => quad.w,
66            _ => unreachable!(),
67        };
68        Vertex {
69            pos: self.vert(vid),
70            normal: no,
71        }
72    }
73
74    fn shared_vertex_count(&self) -> usize {
75        24
76    }
77}
78
79impl IndexedPolygon<Quad<usize>> for Cube {
80    fn indexed_polygon(&self, idx: usize) -> Quad<usize> {
81        Quad::new(idx * 4 + 0, idx * 4 + 1, idx * 4 + 2, idx * 4 + 3)
82    }
83
84    fn indexed_polygon_count(&self) -> usize {
85        6
86    }
87}
genmesh/cube.rs

genmesh/
cube.rs
